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Message-ID: <20251224135217.25350-5-joaopeixoto@osyx.tech>
Date: Wed, 24 Dec 2025 13:52:16 +0000
From: joaopeixoto@...x.tech
To: linux-kernel@...r.kernel.org
Cc: ajd@...ux.ibm.com,
alex@...ti.fr,
aou@...s.berkeley.edu,
bagasdotme@...il.com,
catalin.marinas@....com,
conor+dt@...nel.org,
corbet@....net,
dan.j.williams@...el.com,
davidmcerdeira@...x.tech,
devicetree@...r.kernel.org,
dev@...l-k.io,
gregkh@...uxfoundation.org,
haren@...ux.ibm.com,
heiko@...ech.de,
joaopeixoto@...x.tech,
jose@...x.tech,
kever.yang@...k-chips.com,
krzk+dt@...nel.org,
linux-arm-kernel@...ts.infradead.org,
linux@...linux.org.uk,
linux-doc@...r.kernel.org,
linux-riscv@...ts.infradead.org,
maddy@...ux.ibm.com,
mani@...nel.org,
nathan@...nel.org,
neil.armstrong@...aro.org,
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pjw@...nel.org,
prabhakar.mahadev-lad.rj@...renesas.com,
robh@...nel.org,
will@...nel.org
Subject: [PATCH 4/5] virt: add Bao I/O dispatcher driver
From: João Peixoto <joaopeixoto@...x.tech>
Introduce the Bao I/O Dispatcher, a kernel module that can be loaded
into backend VMs. It provides the bridge between the Bao hypervisor
Remote I/O system (Bao's mechanism for forwarding I/O requests from
frontend VMs to backend VMs) and the VirtIO backend device, offering
a unified API to support various VirtIO backends.
This patch includes:
- Architecture-specific headers for ARM, ARM64, and RISC-V
- Driver framework in drivers/virt/bao/ including dm, driver, intc,
io_client, io_dispatcher, ioctls, ioeventfd, and irqfd
- Kconfig and Makefile entries to enable building the module
- UAPI header for userspace API exposure
- Documentation update for ioctl number references
Signed-off-by: João Peixoto <joaopeixoto@...x.tech>
---
.../userspace-api/ioctl/ioctl-number.rst | 2 +
arch/arm/include/asm/bao.h | 62 +++
arch/arm64/include/asm/bao.h | 62 +++
arch/riscv/include/asm/bao.h | 61 +++
drivers/virt/Makefile | 1 +
drivers/virt/bao/Kconfig | 2 +
drivers/virt/bao/Makefile | 1 +
drivers/virt/bao/io-dispatcher/Kconfig | 16 +
drivers/virt/bao/io-dispatcher/Makefile | 4 +
drivers/virt/bao/io-dispatcher/bao_drv.h | 386 ++++++++++++++++
drivers/virt/bao/io-dispatcher/dm.c | 330 +++++++++++++
drivers/virt/bao/io-dispatcher/driver.c | 348 ++++++++++++++
drivers/virt/bao/io-dispatcher/hypercall.h | 30 ++
drivers/virt/bao/io-dispatcher/intc.c | 68 +++
drivers/virt/bao/io-dispatcher/io_client.c | 435 ++++++++++++++++++
.../virt/bao/io-dispatcher/io_dispatcher.c | 207 +++++++++
drivers/virt/bao/io-dispatcher/ioctls.c | 145 ++++++
drivers/virt/bao/io-dispatcher/ioeventfd.c | 336 ++++++++++++++
drivers/virt/bao/io-dispatcher/irqfd.c | 341 ++++++++++++++
include/uapi/linux/bao.h | 124 +++++
20 files changed, 2961 insertions(+)
create mode 100644 arch/arm/include/asm/bao.h
create mode 100644 arch/arm64/include/asm/bao.h
create mode 100644 arch/riscv/include/asm/bao.h
create mode 100644 drivers/virt/bao/io-dispatcher/Kconfig
create mode 100644 drivers/virt/bao/io-dispatcher/Makefile
create mode 100644 drivers/virt/bao/io-dispatcher/bao_drv.h
create mode 100644 drivers/virt/bao/io-dispatcher/dm.c
create mode 100644 drivers/virt/bao/io-dispatcher/driver.c
create mode 100644 drivers/virt/bao/io-dispatcher/hypercall.h
create mode 100644 drivers/virt/bao/io-dispatcher/intc.c
create mode 100644 drivers/virt/bao/io-dispatcher/io_client.c
create mode 100644 drivers/virt/bao/io-dispatcher/io_dispatcher.c
create mode 100644 drivers/virt/bao/io-dispatcher/ioctls.c
create mode 100644 drivers/virt/bao/io-dispatcher/ioeventfd.c
create mode 100644 drivers/virt/bao/io-dispatcher/irqfd.c
create mode 100644 include/uapi/linux/bao.h
diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 7232b3544cec..b0dbc307a9cb 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -349,6 +349,8 @@ Code Seq# Include File Comments
<mailto:luzmaximilian@...il.com>
0xA5 20-2F linux/surface_aggregator/dtx.h Microsoft Surface DTX driver
<mailto:luzmaximilian@...il.com>
+0xA6 all uapi/linux/bao.h Bao hypervisor
+ <mailto:info@...-project.org>
0xAA 00-3F linux/uapi/linux/userfaultfd.h
0xAB 00-1F linux/nbd.h
0xAC 00-1F linux/raw.h
diff --git a/arch/arm/include/asm/bao.h b/arch/arm/include/asm/bao.h
new file mode 100644
index 000000000000..9474ce459987
--- /dev/null
+++ b/arch/arm/include/asm/bao.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Hypercall for Bao Hypervisor on ARM
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#ifndef __ASM_ARM_BAO_H
+#define __ASM_ARM_BAO_H
+
+#include <asm/bao.h>
+#include <linux/bao.h>
+#include <linux/arm-smccc.h>
+
+/**
+ * asm_bao_hypercall_remio - Perform a Bao Remote I/O hypercall
+ * @request: Bao VirtIO request
+ *
+ * Executes a Bao Remote I/O hypercall using ARM HVC instruction.
+ *
+ * Return: Filled remio_hypercall_ret structure containing the results.
+ */
+static inline struct remio_hypercall_ret
+asm_bao_hypercall_remio(struct bao_virtio_request *request)
+{
+ register int x0 asm("r0") =
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64,
+ ARM_SMCCC_OWNER_VENDOR_HYP, REMIO_HC_ID);
+ register u32 x1 asm("r1") = request->dm_id;
+ register u32 x2 asm("r2") = request->addr;
+ register u32 x3 asm("r3") = request->op;
+ register u32 x4 asm("r4") = request->value;
+ register u32 x5 asm("r5") = request->request_id;
+ register u32 x6 asm("r6") = 0;
+
+ struct remio_hypercall_ret ret;
+
+ asm volatile("hvc 0\n\t"
+ : "=r"(x0), "=r"(x1), "=r"(x2), "=r"(x3), "=r"(x4),
+ "=r"(x5), "=r"(x6)
+ : "r"(x0), "r"(x1), "r"(x2), "r"(x3), "r"(x4), "r"(x5)
+ : "memory");
+
+ ret.hyp_ret = 0;
+ ret.remio_hyp_ret = x0;
+ ret.pending_requests = x6;
+
+ request->addr = x1;
+ request->op = x2;
+ request->value = x3;
+ request->access_width = x4;
+ request->request_id = x5;
+
+ return ret;
+}
+
+#endif /* __ASM_ARM_BAO_H */
diff --git a/arch/arm64/include/asm/bao.h b/arch/arm64/include/asm/bao.h
new file mode 100644
index 000000000000..047b7204edd4
--- /dev/null
+++ b/arch/arm64/include/asm/bao.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Hypercall for Bao Hypervisor on ARM64
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#ifndef __ASM_ARM64_BAO_H
+#define __ASM_ARM64_BAO_H
+
+#include <asm/bao.h>
+#include <linux/bao.h>
+#include <linux/arm-smccc.h>
+
+/**
+ * asm_bao_hypercall_remio - Perform a Bao Remote I/O hypercall
+ * @request: Bao VirtIO request
+ *
+ * Executes a Bao Remote I/O hypercall using ARM64 HVC instruction.
+ *
+ * Return: Filled bao_virtio_request structure containing the results.
+ */
+static inline struct remio_hypercall_ret
+asm_bao_hypercall_remio(struct bao_virtio_request *request)
+{
+ register int x0 asm("x0") =
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64,
+ ARM_SMCCC_OWNER_VENDOR_HYP, REMIO_HC_ID);
+ register u64 x1 asm("x1") = request->dm_id;
+ register u64 x2 asm("x2") = request->addr;
+ register u64 x3 asm("x3") = request->op;
+ register u64 x4 asm("x4") = request->value;
+ register u64 x5 asm("x5") = request->request_id;
+ register u64 x6 asm("x6") = 0;
+
+ struct remio_hypercall_ret ret;
+
+ asm volatile("hvc 0\n\t"
+ : "=r"(x0), "=r"(x1), "=r"(x2), "=r"(x3), "=r"(x4),
+ "=r"(x5), "=r"(x6)
+ : "r"(x0), "r"(x1), "r"(x2), "r"(x3), "r"(x4), "r"(x5)
+ : "memory");
+
+ ret.hyp_ret = 0;
+ ret.remio_hyp_ret = x0;
+ ret.pending_requests = x6;
+
+ request->addr = x1;
+ request->op = x2;
+ request->value = x3;
+ request->access_width = x4;
+ request->request_id = x5;
+
+ return ret;
+}
+
+#endif /* __ASM_ARM64_BAO_H */
diff --git a/arch/riscv/include/asm/bao.h b/arch/riscv/include/asm/bao.h
new file mode 100644
index 000000000000..e2a1bd492a9a
--- /dev/null
+++ b/arch/riscv/include/asm/bao.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Hypercall for Bao Hypervisor on RISC-V
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#ifndef __ASM_RISCV_BAO_H
+#define __ASM_RISCV_BAO_H
+
+#include <asm/sbi.h>
+#include <linux/bao.h>
+
+/**
+ * asm_bao_hypercall_remio - Perform a Bao Remote I/O hypercall
+ * @request: Bao VirtIO request
+ *
+ * Executes a Bao hypercall using inline assembly.
+ *
+ * Return: Filled bao_virtio_request structure containing the results.
+ */
+static inline struct remio_hypercall_ret
+asm_bao_hypercall_remio(struct bao_virtio_request *request)
+{
+ struct remio_hypercall_ret ret;
+
+ register uintptr_t a0 asm("a0") = (uintptr_t)(request->dm_id);
+ register uintptr_t a1 asm("a1") = (uintptr_t)(request->addr);
+ register uintptr_t a2 asm("a2") = (uintptr_t)(request->op);
+ register uintptr_t a3 asm("a3") = (uintptr_t)(request->value);
+ register uintptr_t a4 asm("a4") = (uintptr_t)(request->request_id);
+ register uintptr_t a5 asm("a5") = (uintptr_t)(0);
+ register uintptr_t a6 asm("a6") = (uintptr_t)(REMIO_HC_ID);
+ register uintptr_t a7 asm("a7") = (uintptr_t)(0x08000ba0);
+
+ asm volatile("ecall"
+ : "+r"(a0), "+r"(a1), "+r"(a2), "+r"(a3), "+r"(a4),
+ "+r"(a5), "+r"(a6), "+r"(a7)
+ : "r"(a0), "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5),
+ "r"(a6), "r"(a7)
+ : "memory");
+
+ ret.hyp_ret = a0;
+ ret.remio_hyp_ret = a1;
+ ret.pending_requests = a7;
+
+ request->addr = a2;
+ request->op = a3;
+ request->value = a4;
+ request->access_width = a5;
+ request->request_id = a6;
+
+ return ret;
+}
+
+#endif /* __ASM_RISCV_BAO_H */
diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile
index 623a671f8711..8bffc7ccd29e 100644
--- a/drivers/virt/Makefile
+++ b/drivers/virt/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_NITRO_ENCLAVES) += nitro_enclaves/
obj-$(CONFIG_ACRN_HSM) += acrn/
obj-y += coco/
obj-$(CONFIG_BAO_SHMEM) += bao/
+obj-$(CONFIG_BAO_IO_DISPATCHER) += bao/
diff --git a/drivers/virt/bao/Kconfig b/drivers/virt/bao/Kconfig
index 4f7929d57475..ab08a20db8c4 100644
--- a/drivers/virt/bao/Kconfig
+++ b/drivers/virt/bao/Kconfig
@@ -1,3 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
source "drivers/virt/bao/ipcshmem/Kconfig"
+
+source "drivers/virt/bao/io-dispatcher/Kconfig"
diff --git a/drivers/virt/bao/Makefile b/drivers/virt/bao/Makefile
index 68f5d3f282c4..c463f04cf206 100644
--- a/drivers/virt/bao/Makefile
+++ b/drivers/virt/bao/Makefile
@@ -1,3 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_BAO_SHMEM) += ipcshmem/
+obj-$(CONFIG_BAO_IO_DISPATCHER) += io-dispatcher/
diff --git a/drivers/virt/bao/io-dispatcher/Kconfig b/drivers/virt/bao/io-dispatcher/Kconfig
new file mode 100644
index 000000000000..fc9226e20790
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0
+config BAO_IO_DISPATCHER
+ tristate "Bao Hypervisor I/O Dispatcher"
+ select EVENTFD
+
+ help
+ The Bao I/O Dispatcher is a kernel module for backend Linux VMs
+ running under the Bao hypervisor. It establishes the connection
+ between the Remote I/O system (Bao's mechanism for forwarding
+ I/O requests from frontend VMs to the backend VMs) and the
+ VirtIO backend device.
+
+ This provides a unified API to support various VirtIO backends,
+ allowing Bao guests to perform I/O through the hypervisor
+ transparently.
+
diff --git a/drivers/virt/bao/io-dispatcher/Makefile b/drivers/virt/bao/io-dispatcher/Makefile
new file mode 100644
index 000000000000..19225f524217
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_BAO_IO_DISPATCHER) += bao.o
+bao-objs += ioctls.o ioeventfd.o io_client.o io_dispatcher.o irqfd.o dm.o intc.o driver.o
+
diff --git a/drivers/virt/bao/io-dispatcher/bao_drv.h b/drivers/virt/bao/io-dispatcher/bao_drv.h
new file mode 100644
index 000000000000..4abcdf2eae10
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/bao_drv.h
@@ -0,0 +1,386 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Provides some definitions for the Bao Hypervisor modules
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#ifndef __BAO_DRV_H
+#define __BAO_DRV_H
+
+#include <linux/bao.h>
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/interrupt.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/bitops.h>
+
+#define BAO_IOEVENTFD_FLAG_DATAMATCH BIT(1)
+#define BAO_IOEVENTFD_FLAG_DEASSIGN BIT(2)
+#define BAO_IRQFD_FLAG_DEASSIGN 1U
+#define BAO_IO_CLIENT_DESTROYING 0U
+#define BAO_DM_FLAG_DESTROYING 0U
+#define BAO_DM_FLAG_CLEARING_IOREQ 1U
+
+struct bao_dm;
+struct bao_io_client;
+
+typedef int (*bao_io_client_handler_t)(struct bao_io_client *client,
+ struct bao_virtio_request *req);
+
+/**
+ * struct bao_io_client - Bao I/O client
+ * @name: Client name
+ * @dm: The DM that the client belongs to
+ * @list: List node for this bao_io_client
+ * @is_control: If this client is the control client
+ * @flags: Flags (BAO_IO_CLIENT_*)
+ * @virtio_requests: List of free I/O requests
+ * @range_list: I/O ranges
+ * @handler: I/O request handler for this client
+ * @thread: Kernel thread executing the handler
+ * @wq: Wait queue used for thread parking
+ * @priv: Private data for the handler
+ */
+struct bao_io_client {
+ char name[BAO_NAME_MAX_LEN];
+ struct bao_dm *dm;
+ struct list_head list;
+ bool is_control;
+ unsigned long flags;
+ struct list_head virtio_requests;
+
+ /* protects virtio_requests list */
+ struct mutex virtio_requests_lock;
+
+ struct list_head range_list;
+
+ /* protects range_list */
+ struct rw_semaphore range_lock;
+
+ bao_io_client_handler_t handler;
+ struct task_struct *thread;
+ wait_queue_head_t wq;
+ void *priv;
+};
+
+/**
+ * struct bao_dm - Bao backend device model (DM)
+ * @list: Entry within global list of all DMs
+ * @info: DM information (id, shmem_addr, shmem_size, irq, fd)
+ * @shmem_base_addr: The base address of the shared memory (only used for unmapping purposes)
+ * @flags: Flags (BAO_IO_DISPATCHER_DM_*)
+ * @ioeventfds: List of all ioeventfds
+ * @ioeventfd_client: Ioeventfd client
+ * @irqfds: List of all irqfds
+ * @irqfd_server: Workqueue responsible for irqfd handling
+ * @io_clients: List of all bao_io_client
+ * @control_client: Control client
+ */
+struct bao_dm {
+ struct list_head list;
+ struct bao_dm_info info;
+ void *shmem_base_addr;
+ unsigned long flags;
+
+ struct list_head ioeventfds;
+
+ /* protects ioeventfds list */
+ struct mutex ioeventfds_lock;
+
+ struct bao_io_client *ioeventfd_client;
+
+ struct list_head irqfds;
+
+ /* protects irqfds list */
+ struct mutex irqfds_lock;
+
+ struct workqueue_struct *irqfd_server;
+
+ /* protects io_clients list */
+ struct rw_semaphore io_clients_lock;
+
+ struct list_head io_clients;
+ struct bao_io_client *control_client;
+};
+
+/**
+ * struct bao_io_range - Represents a range of I/O addresses
+ * @list: List node for linking multiple ranges
+ * @start: Start address of the range
+ * @end: End address of the range (inclusive)
+ */
+struct bao_io_range {
+ struct list_head list;
+ u64 start;
+ u64 end;
+};
+
+/* Global list of all Bao device models */
+extern struct list_head bao_dm_list;
+
+/* Lock protecting access to bao_dm_list */
+extern rwlock_t bao_dm_list_lock;
+
+/**
+ * bao_dm_create - Create a backend device model (DM)
+ * @info: DM information (id, shmem_addr, shmem_size, irq, fd)
+ *
+ * Return: Pointer to the created DM on success, NULL on error.
+ */
+struct bao_dm *bao_dm_create(struct bao_dm_info *info);
+
+/**
+ * bao_dm_destroy - Destroy a backend device model (DM)
+ * @dm: DM to be destroyed
+ */
+void bao_dm_destroy(struct bao_dm *dm);
+
+/**
+ * bao_dm_get_info - Retrieve information of a DM
+ * @info: Structure to be filled; id field must contain the DM ID
+ *
+ * Return: true on success, false on error.
+ */
+bool bao_dm_get_info(struct bao_dm_info *info);
+
+/**
+ * bao_dm_ioctl - Handle DM-related ioctls
+ * @filp: Open file pointer
+ * @cmd: IOCTL command
+ * @ioctl_param: Pointer to IOCTL parameter
+ *
+ * Return: ioctl result code.
+ */
+long bao_dm_ioctl(struct file *filp, unsigned int cmd,
+ unsigned long ioctl_param);
+
+/**
+ * bao_io_client_create - Create a backend I/O client
+ * @dm: DM this client belongs to
+ * @handler: I/O client handler for requests
+ * @data: Private data passed to the handler
+ * @is_control: True if this is the control client
+ * @name: Name of the I/O client
+ *
+ * Return: Pointer to the created I/O client, or NULL on failure.
+ */
+struct bao_io_client *bao_io_client_create(struct bao_dm *dm,
+ bao_io_client_handler_t handler,
+ void *data, bool is_control,
+ const char *name);
+
+/**
+ * bao_io_clients_destroy - Destroy all I/O clients of a DM
+ * @dm: DM whose I/O clients are to be destroyed
+ */
+void bao_io_clients_destroy(struct bao_dm *dm);
+
+/**
+ * bao_io_client_attach - Attach a thread to an I/O client
+ * @client: I/O client to attach
+ *
+ * The thread will wait for I/O requests on this client.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_io_client_attach(struct bao_io_client *client);
+
+/**
+ * bao_io_client_range_add - Add an I/O range to monitor in a client
+ * @client: I/O client
+ * @start: Start address of the range
+ * @end: End address of the range (inclusive)
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_io_client_range_add(struct bao_io_client *client, u64 start, u64 end);
+
+/**
+ * bao_io_client_range_del - Remove an I/O range from a client
+ * @client: I/O client
+ * @start: Start address of the range
+ * @end: End address of the range (inclusive)
+ */
+void bao_io_client_range_del(struct bao_io_client *client, u64 start, u64 end);
+
+/**
+ * bao_io_client_request - Retrieve the oldest I/O request from a client
+ * @client: I/O client
+ * @req: Pointer to virtio request structure to fill
+ *
+ * Return: 0 on success, negative error code if no request is available.
+ */
+int bao_io_client_request(struct bao_io_client *client,
+ struct bao_virtio_request *req);
+
+/**
+ * bao_io_client_push_request - Push an I/O request into a client
+ * @client: I/O client
+ * @req: I/O request to push
+ *
+ * Return: true if a request was pushed, false otherwise.
+ */
+bool bao_io_client_push_request(struct bao_io_client *client,
+ struct bao_virtio_request *req);
+
+/**
+ * bao_io_client_pop_request - Pop the oldest I/O request from a client
+ * @client: I/O client
+ * @req: Buffer to store the popped request
+ *
+ * Return: true if a request was popped, false if the queue was empty.
+ */
+bool bao_io_client_pop_request(struct bao_io_client *client, struct bao_virtio_request *req);
+
+/**
+ * bao_io_client_find - Find the I/O client for a given request
+ * @dm: DM that the I/O request belongs to
+ * @req: I/O request to locate
+ *
+ * Return: Pointer to the I/O client handling the request, or NULL if none found.
+ */
+struct bao_io_client *bao_io_client_find(struct bao_dm *dm,
+ struct bao_virtio_request *req);
+
+/**
+ * bao_ioeventfd_client_init - Initialize the Ioeventfd client for a DM
+ * @dm: DM that the Ioeventfd client belongs to
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_ioeventfd_client_init(struct bao_dm *dm);
+
+/**
+ * bao_ioeventfd_client_destroy - Destroy the Ioeventfd client for a DM
+ * @dm: DM that the Ioeventfd client belongs to
+ */
+void bao_ioeventfd_client_destroy(struct bao_dm *dm);
+
+/**
+ * bao_ioeventfd_client_config - Configure an Ioeventfd client
+ * @dm: DM that the Ioeventfd client belongs to
+ * @config: Ioeventfd configuration to apply
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_ioeventfd_client_config(struct bao_dm *dm,
+ struct bao_ioeventfd *config);
+
+/**
+ * bao_irqfd_server_init - Initialize the Irqfd server for a DM
+ * @dm: DM that the Irqfd server belongs to
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_irqfd_server_init(struct bao_dm *dm);
+
+/**
+ * bao_irqfd_server_destroy - Destroy the Irqfd server for a DM
+ * @dm: DM that the Irqfd server belongs to
+ */
+void bao_irqfd_server_destroy(struct bao_dm *dm);
+
+/**
+ * bao_irqfd_server_config - Configure an Irqfd server
+ * @dm: DM that the Irqfd server belongs to
+ * @config: Irqfd configuration to apply
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_irqfd_server_config(struct bao_dm *dm, struct bao_irqfd *config);
+
+/**
+ * bao_io_dispatcher_init - Initialize the I/O Dispatcher for a DM
+ * @dm: DM to initialize on the I/O Dispatcher
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_io_dispatcher_init(struct bao_dm *dm);
+
+/**
+ * bao_io_dispatcher_destroy - Destroy the I/O Dispatcher for a DM
+ * @dm: DM to destroy on the I/O Dispatcher
+ */
+void bao_io_dispatcher_destroy(struct bao_dm *dm);
+
+/**
+ * bao_io_dispatcher_setup - Setup the I/O Dispatcher
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_io_dispatcher_setup(void);
+
+/**
+ * bao_io_dispatcher_remove - Remove the I/O Dispatcher
+ */
+void bao_io_dispatcher_remove(void);
+
+/**
+ * bao_dispatch_io - Acquire and dispatch I/O requests from the Bao Hypervisor
+ * @dm: DM whose I/O clients will handle the requests
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_dispatch_io(struct bao_dm *dm);
+
+/**
+ * bao_io_dispatcher_pause - Pause the I/O Dispatcher for a DM
+ * @dm: DM to pause
+ */
+void bao_io_dispatcher_pause(struct bao_dm *dm);
+
+/**
+ * bao_io_dispatcher_resume - Resume the I/O Dispatcher for a DM
+ * @dm: DM to resume
+ */
+void bao_io_dispatcher_resume(struct bao_dm *dm);
+
+/**
+ * bao_intc_register - Register the interrupt controller for a DM
+ * @dm: DM that the interrupt controller belongs to
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int bao_intc_register(struct bao_dm *dm);
+
+/**
+ * bao_intc_unregister - Unregister the interrupt controller for a DM
+ * @dm: DM that the interrupt controller belongs to
+ */
+void bao_intc_unregister(struct bao_dm *dm);
+
+/**
+ * bao_intc_setup_handler - Setup the interrupt controller handler
+ * @handler: Function pointer to the interrupt handler
+ * @dm: DM that the interrupt controller belongs to
+ */
+void bao_intc_setup_handler(void (*handler)(struct bao_dm *dm));
+
+/**
+ * bao_intc_remove_handler - Remove the interrupt controller handler
+ */
+void bao_intc_remove_handler(void);
+
+/**
+ * bao_io_dispatcher_driver_ioctl - Handle I/O Dispatcher ioctls
+ * @filp: Open file pointer
+ * @cmd: IOCTL command
+ * @ioctl_param: Pointer to IOCTL parameter
+ *
+ * Return: ioctl result code.
+ */
+long bao_io_dispatcher_driver_ioctl(struct file *filp, unsigned int cmd,
+ unsigned long ioctl_param);
+
+#endif /* __BAO_DRV_H */
diff --git a/drivers/virt/bao/io-dispatcher/dm.c b/drivers/virt/bao/io-dispatcher/dm.c
new file mode 100644
index 000000000000..633d9dd206e1
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/dm.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor Backend Device Model (DM)
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include "bao_drv.h"
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/anon_inodes.h>
+#include <linux/miscdevice.h>
+#include "hypercall.h"
+
+/*
+ * List of all backend device models (DMs)
+ */
+LIST_HEAD(bao_dm_list);
+
+/*
+ * Lock to protect bao_dm_list:
+ * - Read: worker thread dispatching I/O requests
+ * - Write: DM creation via ioctl
+ */
+DEFINE_RWLOCK(bao_dm_list_lock);
+
+static int bao_dm_open(struct inode *inode, struct file *filp)
+{
+ return 0;
+}
+
+static int bao_dm_release(struct inode *inode, struct file *filp)
+{
+ struct bao_dm *dm = filp->private_data;
+
+ if (WARN_ON_ONCE(!dm))
+ return -ENODEV;
+
+ bao_dm_destroy(dm);
+
+ kfree(dm);
+ filp->private_data = NULL;
+
+ return 0;
+}
+
+/**
+ * bao_dm_mmap - mmap backend DM shared memory to userspace
+ * @filp: File pointer for the DM device
+ * @vma: Virtual memory area for mapping
+ *
+ * Maps the previously allocated kernel memory region of the backend
+ * DM into the userspace address space.
+ *
+ * Return: 0 on success, negative errno on failure
+ */
+static int bao_dm_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ struct bao_dm *dm = filp->private_data;
+ unsigned long vsize, offset;
+ phys_addr_t phys;
+
+ if (WARN_ON_ONCE(!dm))
+ return -ENODEV;
+
+ vsize = vma->vm_end - vma->vm_start;
+ offset = vma->vm_pgoff << PAGE_SHIFT;
+
+ if (!vsize || offset)
+ return -EINVAL;
+
+ if (vsize > dm->info.shmem_size)
+ return -EINVAL;
+
+ phys = dm->info.shmem_addr;
+ if (!PAGE_ALIGNED(phys))
+ return -EINVAL;
+
+ if (remap_pfn_range(vma, vma->vm_start, phys >> PAGE_SHIFT,
+ vsize, vma->vm_page_prot))
+ return -EFAULT;
+
+ return 0;
+}
+
+/**
+ * bao_dm_llseek - Adjust file offset for backend DM device
+ * @file: File pointer for the DM device
+ * @offset: Offset to seek
+ * @whence: Reference point (SEEK_SET, SEEK_CUR, SEEK_END)
+ *
+ * Adjusts the file position for the backend DM device, allowing
+ * userspace to seek within the shared memory region.
+ *
+ * Return: New file position on success, negative errno on failure
+ */
+static loff_t bao_dm_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct bao_dm *bao = file->private_data;
+ loff_t new_pos;
+
+ if (WARN_ON_ONCE(!bao))
+ return -ENODEV;
+
+ switch (whence) {
+ case SEEK_SET:
+ new_pos = offset;
+ break;
+ case SEEK_CUR:
+ new_pos = file->f_pos + offset;
+ break;
+ case SEEK_END:
+ new_pos = bao->info.shmem_size + offset;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (new_pos < 0 || new_pos > bao->info.shmem_size)
+ return -EINVAL;
+
+ file->f_pos = new_pos;
+ return new_pos;
+}
+
+static const struct file_operations bao_dm_fops = {
+ .owner = THIS_MODULE,
+ .open = bao_dm_open,
+ .release = bao_dm_release,
+ .unlocked_ioctl = bao_dm_ioctl,
+ .llseek = bao_dm_llseek,
+ .mmap = bao_dm_mmap,
+};
+
+struct bao_dm *bao_dm_create(struct bao_dm_info *info)
+{
+ struct bao_dm *dm;
+ char name[BAO_NAME_MAX_LEN];
+
+ if (WARN_ON(!info))
+ return NULL;
+
+ /* Check if a DM with the same ID already exists */
+ read_lock(&bao_dm_list_lock);
+ list_for_each_entry(dm, &bao_dm_list, list) {
+ if (dm->info.id == info->id) {
+ read_unlock(&bao_dm_list_lock);
+ return NULL;
+ }
+ }
+ read_unlock(&bao_dm_list_lock);
+
+ /* Allocate the DM structure */
+ dm = kzalloc(sizeof(*dm), GFP_KERNEL);
+ if (!dm)
+ return NULL;
+
+ INIT_LIST_HEAD(&dm->io_clients);
+ init_rwsem(&dm->io_clients_lock);
+
+ dm->info = *info;
+
+ /* Initialize IO dispatcher */
+ bao_io_dispatcher_init(dm);
+
+ /* Add DM to global list */
+ write_lock_bh(&bao_dm_list_lock);
+ list_add(&dm->list, &bao_dm_list);
+ write_unlock_bh(&bao_dm_list_lock);
+
+ /* Create control client */
+ snprintf(name, sizeof(name), "bao-ioctlc%u", dm->info.id);
+ dm->control_client = bao_io_client_create(dm, NULL, NULL, true, name);
+ if (!dm->control_client) {
+ pr_err("%s: failed to create control client for DM %u\n",
+ __func__, dm->info.id);
+ goto err_remove_dm;
+ }
+
+ /* Initialize IOEVENTFD client */
+ if (bao_ioeventfd_client_init(dm)) {
+ pr_err("%s: failed to initialize ioeventfd for DM %u\n",
+ __func__, dm->info.id);
+ goto err_destroy_io_clients;
+ }
+
+ /* Initialize IRQFD server */
+ if (bao_irqfd_server_init(dm)) {
+ pr_err("%s: failed to initialize irqfd for DM %u\n",
+ __func__, dm->info.id);
+ goto err_destroy_io_clients;
+ }
+
+ /* Map shared memory */
+ dm->shmem_base_addr =
+ memremap(dm->info.shmem_addr, dm->info.shmem_size, MEMREMAP_WB);
+ if (!dm->shmem_base_addr) {
+ pr_err("%s: failed to map memory region for DM %u\n",
+ __func__, dm->info.id);
+ goto err_destroy_irqfd;
+ }
+
+ return dm;
+
+err_destroy_irqfd:
+ bao_irqfd_server_destroy(dm);
+
+err_destroy_io_clients:
+ bao_io_clients_destroy(dm);
+
+err_remove_dm:
+ write_lock_bh(&bao_dm_list_lock);
+ list_del(&dm->list);
+ write_unlock_bh(&bao_dm_list_lock);
+ kfree(dm);
+
+ return NULL;
+}
+
+void bao_dm_destroy(struct bao_dm *dm)
+{
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ /* Mark DM as destroying to prevent concurrent access */
+ set_bit(BAO_DM_FLAG_DESTROYING, &dm->flags);
+
+ /* Remove from global DM list */
+ write_lock_bh(&bao_dm_list_lock);
+ list_del_init(&dm->list);
+ write_unlock_bh(&bao_dm_list_lock);
+
+ /* Clear DM info for safety */
+ dm->info.id = 0;
+ dm->info.shmem_addr = 0;
+ dm->info.shmem_size = 0;
+ dm->info.irq = 0;
+
+ /* Unmap shared memory */
+ if (dm->shmem_base_addr)
+ memunmap(dm->shmem_base_addr);
+
+ /* Close the associated file descriptor if any */
+ if (dm->info.fd >= 0)
+ put_unused_fd(dm->info.fd);
+
+ /* Destroy all server/client resources */
+ bao_irqfd_server_destroy(dm);
+ bao_io_clients_destroy(dm);
+ bao_io_dispatcher_destroy(dm);
+
+ /* Clear destroying flag */
+ clear_bit(BAO_DM_FLAG_DESTROYING, &dm->flags);
+
+ /* Free DM structure */
+ kfree(dm);
+}
+
+/**
+ * bao_dm_create_anonymous_inode - Create an anonymous inode for a backend DM
+ * @dm: The backend device model (DM)
+ *
+ * Creates an anonymous inode that exposes the backend DM to userspace.
+ * The frontend DM can use the returned file descriptor to request
+ * services from the backend DM directly.
+ *
+ * Return: File descriptor on success, negative errno on failure
+ */
+static int bao_dm_create_anonymous_inode(struct bao_dm *dm)
+{
+ char name[BAO_NAME_MAX_LEN];
+ struct file *file;
+ int fd;
+
+ if (WARN_ON_ONCE(!dm))
+ return -EINVAL;
+
+ /* Allocate an unused file descriptor */
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+
+ /* Create anonymous inode for this DM */
+ snprintf(name, sizeof(name), "bao-dm%u", dm->info.id);
+ file = anon_inode_getfile(name, &bao_dm_fops, dm, O_RDWR);
+ if (IS_ERR(file)) {
+ put_unused_fd(fd);
+ return PTR_ERR(file);
+ }
+
+ /* Install the file descriptor and store in DM */
+ fd_install(fd, file);
+ dm->info.fd = fd;
+
+ return fd;
+}
+
+bool bao_dm_get_info(struct bao_dm_info *info)
+{
+ struct bao_dm *dm;
+ bool found = false;
+
+ if (WARN_ON_ONCE(!info))
+ return false;
+
+ /* Search the global DM list for matching ID */
+ list_for_each_entry(dm, &bao_dm_list, list) {
+ if (dm->info.id == info->id) {
+ info->shmem_addr = dm->info.shmem_addr;
+ info->shmem_size = dm->info.shmem_size;
+ info->irq = dm->info.irq;
+
+ /* Create anonymous inode and store FD */
+ info->fd = bao_dm_create_anonymous_inode(dm);
+
+ found = true;
+ break;
+ }
+ }
+
+ return found;
+}
diff --git a/drivers/virt/bao/io-dispatcher/driver.c b/drivers/virt/bao/io-dispatcher/driver.c
new file mode 100644
index 000000000000..11d73107e8ca
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/driver.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor I/O Dispatcher Kernel Driver
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/of_irq.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/uaccess.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include "bao_drv.h"
+
+#define DEV_NAME "bao-io-dispatcher"
+
+static dev_t bao_iodispatcher_devt;
+struct class *bao_iodispatcher_cl;
+
+/**
+ * struct bao_iodispatcher_drv - Bao I/O Dispatcher driver
+ * @cdev: Character device for the dispatcher
+ * @dev: Pointer to the device
+ *
+ * Represents the Bao I/O Dispatcher kernel module instance and its
+ * associated character device.
+ */
+struct bao_iodispatcher_drv {
+ struct cdev cdev;
+ struct device *dev;
+};
+
+/**
+ * bao_io_dispatcher_driver_open_fops - Open the Bao I/O Dispatcher device
+ * @inode: Inode representing the character device
+ * @filp: File pointer for the opened device
+ *
+ * Sets the private_data pointer in @filp to the Bao I/O Dispatcher
+ * driver instance and takes a reference to its kobject.
+ *
+ * Return: 0 on success
+ */
+static int bao_io_dispatcher_driver_open_fops(struct inode *inode,
+ struct file *filp)
+{
+ struct bao_iodispatcher_drv *drv;
+
+ if (WARN_ON_ONCE(!inode || !inode->i_cdev))
+ return -ENODEV;
+
+ drv = container_of(inode->i_cdev, struct bao_iodispatcher_drv, cdev);
+ filp->private_data = drv;
+
+ /* Increment reference count for the underlying device */
+ kobject_get(&drv->dev->kobj);
+
+ return 0;
+}
+
+/**
+ * bao_io_dispatcher_driver_release_fops - Release the Bao I/O Dispatcher device
+ * @inode: Inode representing the character device
+ * @filp: File pointer for the device being released
+ *
+ * Clears the private_data pointer in @filp and drops the reference
+ * to the device's kobject.
+ *
+ * Return: 0 on success
+ */
+static int bao_io_dispatcher_driver_release_fops(struct inode *inode,
+ struct file *filp)
+{
+ struct bao_iodispatcher_drv *drv;
+
+ if (WARN_ON_ONCE(!inode || !inode->i_cdev))
+ return -ENODEV;
+
+ drv = container_of(inode->i_cdev, struct bao_iodispatcher_drv, cdev);
+
+ /* Clear private data to avoid dangling pointer */
+ filp->private_data = NULL;
+
+ /* Decrement reference count of the underlying device */
+ kobject_put(&drv->dev->kobj);
+
+ return 0;
+}
+
+/**
+ * bao_io_dispatcher_driver_ioctl_fops - File operations ioctl handler
+ * @filp: File pointer for the device
+ * @cmd: IOCTL command
+ * @arg: Argument for the IOCTL command
+ *
+ * Wrapper function to call the main Bao I/O Dispatcher IOCTL handler.
+ *
+ * Return: Result from bao_io_dispatcher_driver_ioctl()
+ */
+static long bao_io_dispatcher_driver_ioctl_fops(struct file *filp,
+ unsigned int cmd,
+ unsigned long arg)
+{
+ return bao_io_dispatcher_driver_ioctl(filp, cmd, arg);
+}
+
+static const struct file_operations bao_io_dispatcher_driver_fops = {
+ .owner = THIS_MODULE,
+ .open = bao_io_dispatcher_driver_open_fops,
+ .release = bao_io_dispatcher_driver_release_fops,
+ .unlocked_ioctl = bao_io_dispatcher_driver_ioctl_fops,
+};
+
+/**
+ * bao_io_dispatcher_driver_register - Register the Bao I/O Dispatcher driver
+ * @pdev: Platform device pointer
+ *
+ * This function sets up the Bao I/O Dispatcher backend for the given platform
+ * device. It allocates the character device, creates device models (DMs) for
+ * each backend, registers interrupts, and creates the
+ * device nodes for userspace access.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int bao_io_dispatcher_driver_register(struct platform_device *pdev)
+{
+ int ret, irq;
+ struct module *owner = THIS_MODULE;
+ struct resource *r;
+ dev_t devt;
+ resource_size_t reg_size;
+ struct bao_iodispatcher_drv *drv;
+ struct bao_dm *dm;
+ struct bao_dm_info dm_info;
+
+ /* Setup the I/O dispatcher hardware */
+ ret = bao_io_dispatcher_setup();
+ if (ret) {
+ dev_err(&pdev->dev, "setup I/O Dispatcher failed!\n");
+ return ret;
+ }
+
+ /* Allocate driver structure */
+ drv = devm_kzalloc(&pdev->dev, sizeof(*drv), GFP_KERNEL);
+ if (!drv) {
+ ret = -ENOMEM;
+ goto err_io_dispatcher;
+ }
+
+ /* Create DM instances */
+ for (int i = 0; i < BAO_IO_MAX_DMS; i++) {
+ r = platform_get_resource(pdev, IORESOURCE_MEM, i);
+ if (!r)
+ break;
+
+ irq = platform_get_irq(pdev, i);
+ if (irq < 0) {
+ dev_err(&pdev->dev,
+ "Failed to read interrupt number at index %d\n",
+ i);
+ ret = irq;
+ goto err_unregister_dms;
+ }
+
+ reg_size = resource_size(r);
+
+ dm_info.id = i;
+ dm_info.shmem_addr = (unsigned long)r->start;
+ dm_info.shmem_size = (unsigned long)reg_size;
+ dm_info.irq = irq;
+ dm_info.fd = 0;
+
+ dm = bao_dm_create(&dm_info);
+ if (!dm) {
+ dev_err(&pdev->dev,
+ "failed to create Bao DM %d\n", i);
+ ret = -ENOMEM;
+ goto err_unregister_dms;
+ }
+
+ ret = bao_intc_register(dm);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to register interrupt %d\n", irq);
+ goto err_unregister_dms;
+ }
+ }
+
+ /* Initialize character device */
+ cdev_init(&drv->cdev, &bao_io_dispatcher_driver_fops);
+ drv->cdev.owner = owner;
+
+ devt = MKDEV(MAJOR(bao_iodispatcher_devt), 0);
+ ret = cdev_add(&drv->cdev, devt, 1);
+ if (ret)
+ goto err_unregister_irqs;
+
+ /* Create device node */
+ drv->dev = device_create(bao_iodispatcher_cl, &pdev->dev, devt, drv, DEV_NAME);
+ if (IS_ERR(drv->dev)) {
+ ret = PTR_ERR(drv->dev);
+ goto err_cdev;
+ }
+
+ dev_set_drvdata(drv->dev, drv);
+ return 0;
+
+err_cdev:
+ cdev_del(&drv->cdev);
+
+err_unregister_irqs:
+ list_for_each_entry(dm, &bao_dm_list, list)
+ bao_intc_unregister(dm);
+
+err_unregister_dms:
+ list_for_each_entry(dm, &bao_dm_list, list)
+ bao_dm_destroy(dm);
+
+err_io_dispatcher:
+ bao_io_dispatcher_remove();
+ dev_err(&pdev->dev, "failed initialization\n");
+ return ret;
+}
+
+/**
+ * bao_io_dispatcher_driver_unregister - Unregister the Bao I/O Dispatcher driver
+ * @pdev: Platform device pointer
+ *
+ * This function tears down the Bao I/O Dispatcher backend for the given
+ * platform device. It removes the dispatcher, destroys all backend
+ * device models (DMs), and unregisters their associated interrupts.
+ */
+static void bao_io_dispatcher_driver_unregister(struct platform_device *pdev)
+{
+ struct bao_dm *dm, *tmp;
+
+ /* Remove I/O dispatcher hardware */
+ bao_io_dispatcher_remove();
+
+ /* Destroy all DM instances safely */
+ list_for_each_entry_safe(dm, tmp, &bao_dm_list, list) {
+ /* Remove DM from list and free resources */
+ bao_dm_destroy(dm);
+
+ /* Unregister associated interrupts */
+ bao_intc_unregister(dm);
+ }
+}
+
+static const struct of_device_id bao_io_dispatcher_driver_dt_ids[] = {
+ { .compatible = "bao,io-dispatcher" },
+ { /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, bao_io_dispatcher_driver_dt_ids);
+
+static struct platform_driver bao_io_dispatcher_driver = {
+ .probe = bao_io_dispatcher_driver_register,
+ .remove = bao_io_dispatcher_driver_unregister,
+ .driver = {
+ .name = "bao-io-dispatcher",
+ .of_match_table =
+ of_match_ptr(bao_io_dispatcher_driver_dt_ids),
+ .owner = THIS_MODULE,
+ },
+};
+
+/**
+ * bao_io_dispatcher_driver_init - Module initialization for Bao I/O Dispatcher
+ *
+ * Allocates the character device region, creates the device class, and
+ * registers the platform driver for the Bao I/O Dispatcher.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+static int __init bao_io_dispatcher_driver_init(void)
+{
+ int ret;
+
+ /* Create device class */
+ bao_iodispatcher_cl = class_create(DEV_NAME);
+ if (IS_ERR(bao_iodispatcher_cl)) {
+ ret = PTR_ERR(bao_iodispatcher_cl);
+ pr_err("unable to create class %s\n", DEV_NAME);
+ return ret;
+ }
+
+ /* Allocate character device numbers */
+ ret = alloc_chrdev_region(&bao_iodispatcher_devt, 0, BAO_IO_MAX_DMS, DEV_NAME);
+ if (ret < 0) {
+ pr_err("unable to allocate chrdev region for %s\n", DEV_NAME);
+ class_destroy(bao_iodispatcher_cl);
+ return ret;
+ }
+
+ /* Register the platform driver */
+ ret = platform_driver_register(&bao_io_dispatcher_driver);
+ if (ret < 0) {
+ pr_err("unable to register platform driver for %s\n", DEV_NAME);
+ unregister_chrdev_region(bao_iodispatcher_devt, BAO_IO_MAX_DMS);
+ class_destroy(bao_iodispatcher_cl);
+ }
+
+ return ret;
+}
+
+/**
+ * bao_io_dispatcher_driver_exit - Module cleanup for Bao I/O Dispatcher
+ *
+ * Unregisters the platform driver, frees the character device region, and
+ * destroys the device class.
+ */
+static void __exit bao_io_dispatcher_driver_exit(void)
+{
+ /* Unregister the platform driver */
+ platform_driver_unregister(&bao_io_dispatcher_driver);
+
+ /* Release character device numbers */
+ unregister_chrdev_region(bao_iodispatcher_devt, BAO_IO_MAX_DMS);
+
+ /* Destroy the device class */
+ class_destroy(bao_iodispatcher_cl);
+}
+
+module_init(bao_io_dispatcher_driver_init);
+module_exit(bao_io_dispatcher_driver_exit);
+
+MODULE_AUTHOR("João Peixoto <joaopeixoto@...x.tech>");
+MODULE_AUTHOR("David Cerdeira <davidmcerdeira@...x.tech>");
+MODULE_AUTHOR("José Martins <jose@...x.tech>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Bao Hypervisor I/O Dispatcher Kernel Driver");
diff --git a/drivers/virt/bao/io-dispatcher/hypercall.h b/drivers/virt/bao/io-dispatcher/hypercall.h
new file mode 100644
index 000000000000..49b58075558a
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/hypercall.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Hypercall API for Bao Hypervisor
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#ifndef __BAO_HYPERCALL_H
+#define __BAO_HYPERCALL_H
+
+#include <asm/bao.h>
+#include <linux/bao.h>
+
+/**
+ * bao_hypercall_remio() - Performs a Remote I/O Hypercall
+ * @request: Bao VirtIO request
+ *
+ * @return: The VirtIO request structure
+ */
+static inline struct remio_hypercall_ret bao_hypercall_remio(struct bao_virtio_request *request)
+{
+ return asm_bao_hypercall_remio(request);
+}
+
+#endif /* __BAO_HYPERCALL_H */
diff --git a/drivers/virt/bao/io-dispatcher/intc.c b/drivers/virt/bao/io-dispatcher/intc.c
new file mode 100644
index 000000000000..61c0248c0a8e
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/intc.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor I/O Dispatcher Interrupt Controller
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/of_irq.h>
+#include "bao_drv.h"
+
+/* Top-level handler registered by the Bao interrupt controller */
+static void (*bao_intc_handler)(struct bao_dm *dm);
+
+/**
+ * bao_interrupt_handler - Top-level interrupt handler for Bao DM
+ * @irq: Interrupt number
+ * @dev: Pointer to the Bao device model (struct bao_dm)
+ *
+ * Invokes the registered Bao interrupt controller handler, if any.
+ */
+static irqreturn_t bao_interrupt_handler(int irq, void *dev)
+{
+ struct bao_dm *dm = (struct bao_dm *)dev;
+
+ if (bao_intc_handler)
+ bao_intc_handler(dm);
+
+ return IRQ_HANDLED;
+}
+
+void bao_intc_setup_handler(void (*handler)(struct bao_dm *dm))
+{
+ bao_intc_handler = handler;
+}
+
+void bao_intc_remove_handler(void)
+{
+ bao_intc_handler = NULL;
+}
+
+int bao_intc_register(struct bao_dm *dm)
+{
+ char name[BAO_NAME_MAX_LEN];
+
+ if (WARN_ON_ONCE(!dm))
+ return -EINVAL;
+
+ scnprintf(name, sizeof(name), "bao-iodintc%d", dm->info.id);
+
+ return request_irq(dm->info.irq, bao_interrupt_handler, 0, name, dm);
+}
+
+void bao_intc_unregister(struct bao_dm *dm)
+{
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ free_irq(dm->info.irq, dm);
+}
diff --git a/drivers/virt/bao/io-dispatcher/io_client.c b/drivers/virt/bao/io-dispatcher/io_client.c
new file mode 100644
index 000000000000..ab7fb46c5e6a
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/io_client.c
@@ -0,0 +1,435 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor I/O Client
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include "bao_drv.h"
+#include "hypercall.h"
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/io.h>
+
+/**
+ * struct bao_io_request - Bao I/O request structure
+ * @list: List node linking all requests
+ * @virtio_request: The VirtIO I/O request payload
+ *
+ * Represents a single I/O request for a Bao I/O client.
+ */
+struct bao_io_request {
+ struct list_head list;
+ struct bao_virtio_request virtio_request;
+};
+
+/**
+ * bao_io_client_has_pending_requests - Check if an I/O client has pending requests
+ * @client: The bao_io_client to check
+ *
+ * Return true if there are pending VirtIO requests.
+ */
+static inline bool
+bao_io_client_has_pending_requests(struct bao_io_client *client)
+{
+ if (WARN_ON_ONCE(!client))
+ return false;
+
+ return !list_empty(&client->virtio_requests);
+}
+
+/**
+ * bao_io_client_is_destroying - Check if an I/O client is being destroyed
+ * @client: The bao_io_client to check
+ *
+ * Return true if the client is in the process of being destroyed.
+ */
+static inline bool bao_io_client_is_destroying(struct bao_io_client *client)
+{
+ if (WARN_ON_ONCE(!client))
+ return true;
+
+ return test_bit(BAO_IO_CLIENT_DESTROYING, &client->flags);
+}
+
+bool bao_io_client_push_request(struct bao_io_client *client,
+ struct bao_virtio_request *req)
+{
+ struct bao_io_request *io_req;
+
+ if (WARN_ON_ONCE(!client || !req))
+ return false;
+
+ io_req = kzalloc(sizeof(*io_req), GFP_KERNEL);
+ if (!io_req)
+ return false;
+
+ io_req->virtio_request = *req;
+
+ mutex_lock(&client->virtio_requests_lock);
+ list_add_tail(&io_req->list, &client->virtio_requests);
+ mutex_unlock(&client->virtio_requests_lock);
+
+ return true;
+}
+
+bool bao_io_client_pop_request(struct bao_io_client *client, struct bao_virtio_request *ret)
+{
+ struct bao_io_request *req;
+
+ if (WARN_ON_ONCE(!client || !ret))
+ return false;
+
+ mutex_lock(&client->virtio_requests_lock);
+
+ /* Get the first request or NULL if list is empty */
+ req = list_first_entry_or_null(&client->virtio_requests,
+ struct bao_io_request, list);
+ if (!req) {
+ mutex_unlock(&client->virtio_requests_lock);
+ return false;
+ }
+
+ /* Remove from list and copy the virtio request */
+ list_del(&req->list);
+ *ret = req->virtio_request;
+
+ mutex_unlock(&client->virtio_requests_lock);
+
+ /* Free the allocated request */
+ kfree(req);
+
+ return true;
+}
+
+/**
+ * bao_io_client_destroy - Destroy an I/O client
+ * @client: The bao_io_client to destroy
+ *
+ * Stops the client's thread if needed, frees all I/O ranges, removes
+ * the client from its DM lists, and releases associated resources.
+ */
+static void bao_io_client_destroy(struct bao_io_client *client)
+{
+ struct bao_io_client *range, *next;
+ struct bao_dm *dm;
+
+ if (WARN_ON_ONCE(!client))
+ return;
+
+ dm = client->dm;
+
+ /* Pause the IO dispatcher to avoid races */
+ bao_io_dispatcher_pause(dm);
+
+ /* Mark client as destroying */
+ set_bit(BAO_IO_CLIENT_DESTROYING, &client->flags);
+
+ /* Stop client-specific resources */
+ if (client->is_control) {
+ wake_up_interruptible(&client->wq);
+ } else {
+ /* Stop eventfd client and associated thread */
+ bao_ioeventfd_client_destroy(dm);
+ if (client->thread)
+ kthread_stop(client->thread);
+ }
+
+ /* Free range list safely */
+ down_write(&client->range_lock);
+ list_for_each_entry_safe(range, next, &client->range_list, list) {
+ list_del(&range->list);
+ kfree(range);
+ }
+ up_write(&client->range_lock);
+
+ /* Remove client from DM */
+ down_write(&dm->io_clients_lock);
+ if (client->is_control)
+ dm->control_client = NULL;
+ else
+ dm->ioeventfd_client = NULL;
+
+ list_del(&client->list);
+ up_write(&dm->io_clients_lock);
+
+ /* Resume the IO dispatcher */
+ bao_io_dispatcher_resume(dm);
+
+ /* Free the client structure */
+ kfree(client);
+}
+
+void bao_io_clients_destroy(struct bao_dm *dm)
+{
+ struct bao_io_client *client, *next;
+
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ list_for_each_entry_safe(client, next, &dm->io_clients, list) {
+ bao_io_client_destroy(client);
+ }
+}
+
+int bao_io_client_attach(struct bao_io_client *client)
+{
+ if (WARN_ON_ONCE(!client))
+ return -EINVAL;
+
+ if (client->is_control) {
+ /*
+ * In the Control client, a user space thread waits on the waitqueue.
+ * The thread should wait until:
+ * - There are pending I/O requests to be processed
+ * - The I/O client is going to be destroyed
+ */
+ wait_event_interruptible(client->wq,
+ bao_io_client_has_pending_requests(client) ||
+ bao_io_client_is_destroying(client));
+ if (bao_io_client_is_destroying(client))
+ return -EPERM;
+ } else {
+ /*
+ * In the non-control client (e.g., Ioeventfd Client), a kernel space
+ * thread waits on the waitqueue.
+ * The thread should wait until:
+ * - There are pending I/O requests to be processed
+ * - The I/O client is going to be destroyed
+ * - The kernel thread is going to be stopped
+ */
+ wait_event_interruptible(client->wq,
+ bao_io_client_has_pending_requests(client) ||
+ bao_io_client_is_destroying(client) ||
+ kthread_should_stop());
+ if (bao_io_client_is_destroying(client) ||
+ kthread_should_stop()) {
+ if (kthread_should_stop())
+ bao_io_client_destroy(client);
+ return -EPERM;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * bao_io_client_kernel_thread - Thread for processing a kernel I/O client
+ * @data: Pointer to the bao_io_client structure
+ *
+ * Return: 0 on completion
+ */
+static int bao_io_client_kernel_thread(void *data)
+{
+ struct bao_io_client *client = data;
+ struct bao_virtio_request req;
+ struct remio_hypercall_ret hret;
+ bool stop = false;
+ int ret;
+
+ if (WARN_ON_ONCE(!client))
+ return -EINVAL;
+
+ while (!stop && !kthread_should_stop()) {
+ /* Attach client and wait for pending requests or destruction */
+ ret = bao_io_client_attach(client);
+ if (ret < 0) {
+ stop = true;
+ break;
+ }
+
+ /* Process all pending requests */
+ while (bao_io_client_has_pending_requests(client) && !stop) {
+ if (!bao_io_client_pop_request(client, &req)) {
+ pr_err("%s: failed to pop I/O request\n", __func__);
+ stop = true;
+ break;
+ }
+
+ /* Invoke the client's handler */
+ ret = client->handler(client, &req);
+ if (ret < 0) {
+ pr_warn("%s: client handler returned %d\n", __func__, ret);
+ break;
+ }
+
+ /* Perform hypercall */
+ hret = bao_hypercall_remio(&req);
+ if (hret.hyp_ret || hret.remio_hyp_ret) {
+ pr_err("%s: hypercall failed: hyp_ret=%lld, remio_hyp_ret=%lld\n",
+ __func__, hret.hyp_ret, hret.remio_hyp_ret);
+ stop = true;
+ break;
+ }
+ }
+ }
+
+ return 0;
+}
+
+struct bao_io_client *bao_io_client_create(struct bao_dm *dm,
+ bao_io_client_handler_t handler,
+ void *data, bool is_control,
+ const char *name)
+{
+ struct bao_io_client *client;
+
+ if (WARN_ON_ONCE(!dm || !name))
+ return NULL;
+
+ if (!handler && !is_control)
+ return NULL;
+
+ client = kzalloc(sizeof(*client), GFP_KERNEL);
+ if (!client)
+ return NULL;
+
+ /* Initialize client fields */
+ client->handler = handler;
+ client->dm = dm;
+ client->priv = data;
+ client->is_control = is_control;
+ if (name)
+ strscpy(client->name, name, sizeof(client->name));
+
+ INIT_LIST_HEAD(&client->virtio_requests);
+ init_rwsem(&client->range_lock);
+ INIT_LIST_HEAD(&client->range_list);
+ init_waitqueue_head(&client->wq);
+
+ /* Start kernel thread if handler is provided */
+ if (client->handler) {
+ client->thread = kthread_run(bao_io_client_kernel_thread,
+ client, "%s-kthread",
+ client->name);
+ if (IS_ERR(client->thread)) {
+ kfree(client);
+ return NULL;
+ }
+ }
+
+ /* Add client to DM safely */
+ down_write(&dm->io_clients_lock);
+ if (is_control)
+ dm->control_client = client;
+ else
+ dm->ioeventfd_client = client;
+
+ list_add(&client->list, &dm->io_clients);
+ up_write(&dm->io_clients_lock);
+
+ /* Process any pending requests for control client */
+ if (is_control) {
+ while (bao_dispatch_io(dm) > 0)
+ ;
+ }
+
+ return client;
+}
+
+int bao_io_client_request(struct bao_io_client *client,
+ struct bao_virtio_request *req)
+{
+ if (WARN_ON_ONCE(!client))
+ return -EINVAL;
+
+ if (!bao_io_client_pop_request(client, req))
+ return -EFAULT;
+
+ return 0;
+}
+
+int bao_io_client_range_add(struct bao_io_client *client, u64 start, u64 end)
+{
+ struct bao_io_range *range;
+
+ if (WARN_ON_ONCE(!client))
+ return -EINVAL;
+
+ if (end < start)
+ return -EINVAL;
+
+ range = kzalloc(sizeof(*range), GFP_KERNEL);
+ if (!range)
+ return -ENOMEM;
+
+ range->start = start;
+ range->end = end;
+
+ /* Add the range to the client's list safely */
+ down_write(&client->range_lock);
+ list_add(&range->list, &client->range_list);
+ up_write(&client->range_lock);
+
+ return 0;
+}
+
+void bao_io_client_range_del(struct bao_io_client *client, u64 start, u64 end)
+{
+ struct bao_io_range *range, *tmp;
+
+ if (WARN_ON_ONCE(!client))
+ return;
+
+ down_write(&client->range_lock);
+ list_for_each_entry_safe(range, tmp, &client->range_list, list) {
+ if (range->start == start && range->end == end) {
+ list_del(&range->list);
+ kfree(range);
+ break;
+ }
+ }
+ up_write(&client->range_lock);
+}
+
+/**
+ * bao_io_request_in_range - Check if the I/O request is in the range
+ * @range: The I/O request range
+ * @req: The I/O request to be checked
+ *
+ * @return True if the I/O request is in the range, False otherwise
+ */
+static bool bao_io_request_in_range(struct bao_io_range *range,
+ struct bao_virtio_request *req)
+{
+ if (WARN_ON_ONCE(!range || !req))
+ return false;
+
+ if (req->addr >= range->start &&
+ (req->addr + req->access_width - 1) <= range->end)
+ return true;
+
+ return false;
+}
+
+struct bao_io_client *bao_io_client_find(struct bao_dm *dm,
+ struct bao_virtio_request *req)
+{
+ struct bao_io_client *client, *found = NULL;
+ struct bao_io_range *range;
+
+ if (WARN_ON_ONCE(!dm || !req))
+ return NULL;
+
+ list_for_each_entry(client, &dm->io_clients, list) {
+ down_read(&client->range_lock);
+ list_for_each_entry(range, &client->range_list, list) {
+ if (bao_io_request_in_range(range, req)) {
+ found = client;
+ break;
+ }
+ }
+ up_read(&client->range_lock);
+
+ if (found)
+ break;
+ }
+
+ /* Fallback to control client if no matching client found */
+ return found ? found : dm->control_client;
+}
diff --git a/drivers/virt/bao/io-dispatcher/io_dispatcher.c b/drivers/virt/bao/io-dispatcher/io_dispatcher.c
new file mode 100644
index 000000000000..a7aa768f98ca
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/io_dispatcher.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor I/O Dispatcher
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kthread.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/eventfd.h>
+#include <linux/workqueue.h>
+#include <linux/delay.h>
+
+#include <linux/bao.h>
+#include "bao_drv.h"
+#include "hypercall.h"
+
+/**
+ * struct bao_io_dispatcher_work - Work item for I/O dispatching
+ * @work: Work struct for scheduling on workqueue
+ * @dm: Pointer to the associated Bao device model
+ *
+ * Represents a single work item that dispatches I/O requests
+ * for a specific Bao device model.
+ */
+struct bao_io_dispatcher_work {
+ struct work_struct work;
+ struct bao_dm *dm;
+};
+
+/* Array of I/O dispatcher work items, one per Bao DM */
+static struct bao_io_dispatcher_work io_dispatcher_work[BAO_IO_MAX_DMS];
+
+/* Workqueues dedicated to dispatching I/O requests for each Bao DM */
+static struct workqueue_struct *bao_io_dispatcher_wq[BAO_IO_MAX_DMS];
+
+void bao_io_dispatcher_destroy(struct bao_dm *dm)
+{
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ if (bao_io_dispatcher_wq[dm->info.id]) {
+ /* Pause dispatching to prevent races */
+ bao_io_dispatcher_pause(dm);
+
+ /* Destroy the workqueue */
+ destroy_workqueue(bao_io_dispatcher_wq[dm->info.id]);
+ bao_io_dispatcher_wq[dm->info.id] = NULL;
+
+ /* Remove the registered interrupt handler */
+ bao_intc_remove_handler();
+ }
+}
+
+int bao_dispatch_io(struct bao_dm *dm)
+{
+ struct bao_io_client *client;
+ struct bao_virtio_request req;
+ struct remio_hypercall_ret ret;
+
+ if (WARN_ON_ONCE(!dm))
+ return -EINVAL;
+
+ /* Prepare request for hypercall */
+ req.dm_id = dm->info.id;
+ req.op = BAO_IO_ASK;
+ req.addr = 0;
+ req.value = 0;
+ req.request_id = 0;
+
+ /* Perform hypercall to retrieve I/O request */
+ ret = bao_hypercall_remio(&req);
+ if (ret.hyp_ret || ret.remio_hyp_ret)
+ return -EFAULT;
+
+ /* Find the appropriate client for this request */
+ down_read(&dm->io_clients_lock);
+ client = bao_io_client_find(dm, &req);
+ if (!client) {
+ up_read(&dm->io_clients_lock);
+ return -EEXIST;
+ }
+
+ /* Push request to client's queue */
+ if (!bao_io_client_push_request(client, &req)) {
+ up_read(&dm->io_clients_lock);
+ return -EINVAL;
+ }
+
+ /* Wake up the client thread if waiting */
+ wake_up_interruptible(&client->wq);
+ up_read(&dm->io_clients_lock);
+
+ /* Return the number of pending requests left to process */
+ return ret.pending_requests;
+}
+
+/**
+ * io_dispatcher - Workqueue handler for dispatching I/O
+ * @work: Work struct representing this dispatch operation
+ *
+ * Handles all pending I/O requests for the associated Bao DM.
+ * Executed in process context by the workqueue.
+ */
+static void io_dispatcher(struct work_struct *work)
+{
+ struct bao_io_dispatcher_work *bao_dm_work;
+ struct bao_dm *dm;
+
+ if (WARN_ON_ONCE(!work))
+ return;
+
+ bao_dm_work = container_of(work, struct bao_io_dispatcher_work, work);
+ dm = bao_dm_work->dm;
+
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ /*
+ * Dispatch I/O requests for the device model
+ * until there are no more pending requests.
+ */
+ while (bao_dispatch_io(dm) > 0)
+ cpu_relax();
+}
+
+/**
+ * io_dispatcher_intc_handler - Interrupt handler for I/O requests
+ * @dm: Bao device model that triggered the interrupt
+ *
+ * Invoked by the interrupt controller when a new I/O request is available.
+ * Queues the corresponding work item onto the I/O dispatcher workqueue
+ * for processing in process context.
+ */
+static void io_dispatcher_intc_handler(struct bao_dm *dm)
+{
+ if (WARN_ON_ONCE(!dm || !bao_io_dispatcher_wq[dm->info.id]))
+ return;
+
+ queue_work(bao_io_dispatcher_wq[dm->info.id],
+ &io_dispatcher_work[dm->info.id].work);
+}
+
+void bao_io_dispatcher_pause(struct bao_dm *dm)
+{
+ if (WARN_ON_ONCE(!dm || !bao_io_dispatcher_wq[dm->info.id]))
+ return;
+
+ /* Remove the interrupt handler to prevent new work */
+ bao_intc_remove_handler();
+
+ /* Drain any pending work to ensure no tasks are running */
+ drain_workqueue(bao_io_dispatcher_wq[dm->info.id]);
+}
+
+void bao_io_dispatcher_resume(struct bao_dm *dm)
+{
+ if (WARN_ON_ONCE(!dm || !bao_io_dispatcher_wq[dm->info.id]))
+ return;
+
+ /* Reinstall the interrupt handler */
+ bao_intc_setup_handler(io_dispatcher_intc_handler);
+
+ /* Queue a work item to resume dispatching */
+ queue_work(bao_io_dispatcher_wq[dm->info.id],
+ &io_dispatcher_work[dm->info.id].work);
+}
+
+int bao_io_dispatcher_init(struct bao_dm *dm)
+{
+ char name[BAO_NAME_MAX_LEN];
+
+ if (WARN_ON_ONCE(!dm))
+ return -EINVAL;
+
+ snprintf(name, sizeof(name), "bao-iodwq%u", dm->info.id);
+
+ bao_io_dispatcher_wq[dm->info.id] =
+ alloc_workqueue(name, WQ_HIGHPRI | WQ_MEM_RECLAIM, 1);
+ if (!bao_io_dispatcher_wq[dm->info.id])
+ return -ENOMEM;
+
+ io_dispatcher_work[dm->info.id].dm = dm;
+ INIT_WORK(&io_dispatcher_work[dm->info.id].work, io_dispatcher);
+
+ /* Setup interrupt handler for this dispatcher */
+ bao_intc_setup_handler(io_dispatcher_intc_handler);
+
+ return 0;
+}
+
+int bao_io_dispatcher_setup(void)
+{
+ return 0;
+}
+
+void bao_io_dispatcher_remove(void)
+{
+}
diff --git a/drivers/virt/bao/io-dispatcher/ioctls.c b/drivers/virt/bao/io-dispatcher/ioctls.c
new file mode 100644
index 000000000000..77a177800882
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/ioctls.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor IOCTLs Handler for the I/O Dispatcher kernel module
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/file.h>
+#include <linux/cpu.h>
+#include <linux/mm.h>
+#include <linux/miscdevice.h>
+#include <linux/anon_inodes.h>
+#include <linux/bao.h>
+#include "bao_drv.h"
+#include "hypercall.h"
+
+long bao_io_dispatcher_driver_ioctl(struct file *filp, unsigned int cmd,
+ unsigned long arg)
+{
+ struct bao_dm_info *info;
+
+ switch (cmd) {
+ case BAO_IOCTL_DM_GET_INFO:
+ info = memdup_user((void __user *)arg, sizeof(*info));
+ if (IS_ERR(info))
+ return PTR_ERR(info);
+
+ if (!bao_dm_get_info(info)) {
+ kfree(info);
+ return -ENOENT;
+ }
+
+ if (copy_to_user((void __user *)arg, info, sizeof(*info))) {
+ kfree(info);
+ return -EFAULT;
+ }
+
+ kfree(info);
+ return 0;
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+long bao_dm_ioctl(struct file *filp, unsigned int cmd,
+ unsigned long arg)
+{
+ struct bao_dm *dm = filp->private_data;
+ int rc;
+
+ if (WARN_ON_ONCE(!dm))
+ return -ENODEV;
+
+ switch (cmd) {
+ case BAO_IOCTL_IO_CLIENT_ATTACH: {
+ struct bao_virtio_request *req;
+
+ req = memdup_user((void __user *)arg, sizeof(*req));
+ if (IS_ERR(req)) {
+ rc = PTR_ERR(req);
+ break;
+ }
+
+ if (!dm->control_client) {
+ rc = -ENOENT;
+ goto out_free;
+ }
+
+ rc = bao_io_client_attach(dm->control_client);
+ if (rc)
+ goto out_free;
+
+ rc = bao_io_client_request(dm->control_client, req);
+ if (rc)
+ goto out_free;
+
+ if (copy_to_user((void __user *)arg, req, sizeof(*req))) {
+ rc = -EFAULT;
+ goto out_free;
+ }
+
+ rc = 0;
+
+out_free:
+ kfree(req);
+ break;
+ }
+ case BAO_IOCTL_IO_REQUEST_COMPLETE: {
+ struct bao_virtio_request *req;
+ struct remio_hypercall_ret hret;
+
+ req = memdup_user((void __user *)arg, sizeof(*req));
+ if (IS_ERR(req)) {
+ rc = PTR_ERR(req);
+ break;
+ }
+
+ hret = bao_hypercall_remio(req);
+ kfree(req);
+
+ /* Translate hypercall result to proper errno */
+ if (hret.hyp_ret || hret.remio_hyp_ret)
+ rc = -EIO;
+ else
+ rc = 0;
+
+ break;
+ }
+ case BAO_IOCTL_IOEVENTFD: {
+ struct bao_ioeventfd ioeventfd;
+
+ if (copy_from_user(&ioeventfd, (void __user *)arg,
+ sizeof(struct bao_ioeventfd)))
+ return -EFAULT;
+
+ rc = bao_ioeventfd_client_config(dm, &ioeventfd);
+ break;
+ }
+ case BAO_IOCTL_IRQFD: {
+ struct bao_irqfd irqfd;
+
+ if (copy_from_user(&irqfd, (void __user *)arg,
+ sizeof(struct bao_irqfd)))
+ return -EFAULT;
+
+ rc = bao_irqfd_server_config(dm, &irqfd);
+ break;
+ }
+ default:
+ rc = -ENOTTY;
+ break;
+ }
+
+ return rc;
+}
diff --git a/drivers/virt/bao/io-dispatcher/ioeventfd.c b/drivers/virt/bao/io-dispatcher/ioeventfd.c
new file mode 100644
index 000000000000..8eb92193e31b
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/ioeventfd.c
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor Ioeventfd Client
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include "bao_drv.h"
+#include <linux/eventfd.h>
+
+/**
+ * struct ioeventfd - Properties of an I/O eventfd
+ * @list: List node linking this ioeventfd
+ * @eventfd: Associated eventfd context
+ * @addr: Start address of the I/O range
+ * @data: Data used for matching (if not wildcard)
+ * @length: Length of the I/O range
+ * @wildcard: True if data matching is not required
+ *
+ * Represents an I/O eventfd registered for a Bao device model.
+ */
+struct ioeventfd {
+ struct list_head list;
+ struct eventfd_ctx *eventfd;
+ u64 addr;
+ u64 data;
+ int length;
+ bool wildcard;
+};
+
+/**
+ * bao_ioeventfd_shutdown - Release and remove an ioeventfd
+ * @dm: Bao device model owning the ioeventfd (lock must be held)
+ * @p: Ioeventfd to shut down
+ */
+static void bao_ioeventfd_shutdown(struct bao_dm *dm, struct ioeventfd *p)
+{
+ lockdep_assert_held(&dm->ioeventfds_lock);
+
+ if (WARN_ON_ONCE(!p))
+ return;
+
+ eventfd_ctx_put(p->eventfd);
+ list_del(&p->list);
+ kfree(p);
+}
+
+/**
+ * bao_ioeventfd_config_valid - Validate ioeventfd configuration
+ * @config: Ioeventfd configuration
+ *
+ * Returns true if config is non-NULL, address+length does not wrap,
+ * and length is 1, 2, 4, or 8 bytes.
+ */
+static bool bao_ioeventfd_config_valid(struct bao_ioeventfd *config)
+{
+ if (WARN_ON_ONCE(!config))
+ return false;
+
+ /* Check for address overflow */
+ if (config->addr + config->len < config->addr)
+ return false;
+
+ /* Only allow standard byte widths */
+ if (!(config->len == 1 || config->len == 2 || config->len == 4 ||
+ config->len == 8))
+ return false;
+
+ return true;
+}
+
+/**
+ * bao_ioeventfd_is_conflict - Check if an ioeventfd conflicts with existing ones
+ * @dm: Bao device model (lock must be held)
+ * @ioeventfd: Ioeventfd to check
+ *
+ * Returns true if an existing ioeventfd matches address, eventfd,
+ * and optionally data.
+ */
+static bool bao_ioeventfd_is_conflict(struct bao_dm *dm,
+ struct ioeventfd *ioeventfd)
+{
+ struct ioeventfd *p;
+
+ lockdep_assert_held(&dm->ioeventfds_lock);
+
+ if (WARN_ON_ONCE(!dm || !ioeventfd))
+ return true;
+
+ list_for_each_entry(p, &dm->ioeventfds, list) {
+ if (p->eventfd == ioeventfd->eventfd &&
+ p->addr == ioeventfd->addr &&
+ (p->wildcard || ioeventfd->wildcard || p->data == ioeventfd->data)) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/**
+ * bao_ioeventfd_match - Find ioeventfd matching an I/O request
+ * @dm: Bao device model (lock must be held)
+ * @addr: I/O request address
+ * @data: I/O request data
+ * @len: I/O request length
+ *
+ * Returns the matching ioeventfd, or NULL if none matches.
+ */
+static struct ioeventfd *bao_ioeventfd_match(struct bao_dm *dm, u64 addr,
+ u64 data, int len)
+{
+ struct ioeventfd *p;
+
+ lockdep_assert_held(&dm->ioeventfds_lock);
+
+ if (WARN_ON_ONCE(!dm))
+ return NULL;
+
+ list_for_each_entry(p, &dm->ioeventfds, list) {
+ if (p->addr == addr &&
+ p->length >= len &&
+ (p->wildcard || p->data == data)) {
+ return p;
+ }
+ }
+
+ return NULL;
+}
+
+/**
+ * bao_ioeventfd_assign - Assign and create an eventfd for a DM
+ * @dm: Bao device model to assign the eventfd to
+ * @config: Configuration of the eventfd to create
+ *
+ * Creates a new ioeventfd associated with the given eventfd and
+ * adds it to the Bao DM. Validates the configuration, checks for
+ * conflicts with existing ioeventfds, and registers the corresponding
+ * I/O client address range. Supports optional data matching for
+ * virtio 1.0 notifications; if not set, wildcard matching is used.
+ *
+ * Returns 0 on success or a negative error code on failure:
+ * -EINVAL: Invalid configuration
+ * -ENOMEM: Memory allocation failure
+ * -EEXIST: Conflicting ioeventfd already exists
+ * Other negative values may be returned by bao_io_client_range_add().
+ */
+static int bao_ioeventfd_assign(struct bao_dm *dm, struct bao_ioeventfd *config)
+{
+ struct eventfd_ctx *eventfd;
+ struct ioeventfd *new;
+ int rc = 0;
+
+ if (WARN_ON_ONCE(!dm || !config))
+ return -EINVAL;
+
+ if (!bao_ioeventfd_config_valid(config))
+ return -EINVAL;
+
+ eventfd = eventfd_ctx_fdget(config->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ new = kzalloc(sizeof(*new), GFP_KERNEL);
+ if (!new) {
+ rc = -ENOMEM;
+ goto err_put_eventfd;
+ }
+
+ INIT_LIST_HEAD(&new->list);
+ new->addr = config->addr;
+ new->length = config->len;
+ new->eventfd = eventfd;
+ new->wildcard = !(config->flags & BAO_IOEVENTFD_FLAG_DATAMATCH);
+ if (!new->wildcard)
+ new->data = config->data;
+
+ mutex_lock(&dm->ioeventfds_lock);
+
+ if (bao_ioeventfd_is_conflict(dm, new)) {
+ rc = -EEXIST;
+ goto err_unlock_free;
+ }
+
+ rc = bao_io_client_range_add(dm->ioeventfd_client,
+ new->addr, new->addr + new->length - 1);
+ if (rc < 0)
+ goto err_unlock_free;
+
+ list_add_tail(&new->list, &dm->ioeventfds);
+ mutex_unlock(&dm->ioeventfds_lock);
+
+ return 0;
+
+err_unlock_free:
+ mutex_unlock(&dm->ioeventfds_lock);
+ kfree(new);
+err_put_eventfd:
+ eventfd_ctx_put(eventfd);
+ return rc;
+}
+
+/**
+ * bao_ioeventfd_deassign - Deassign and destroy an eventfd from a DM
+ * @dm: Bao device model to deassign the eventfd from
+ * @config: Configuration of the eventfd to remove
+ *
+ * Finds the ioeventfd associated with the given eventfd and removes
+ * it from the Bao DM. The corresponding I/O client range is deleted,
+ * the ioeventfd is shut down, and the eventfd context is released.
+ *
+ * Returns 0 on success or a negative error code if the eventfd lookup fails.
+ */
+static int bao_ioeventfd_deassign(struct bao_dm *dm,
+ struct bao_ioeventfd *config)
+{
+ struct ioeventfd *p;
+ struct eventfd_ctx *eventfd;
+
+ if (WARN_ON_ONCE(!dm || !config))
+ return -EINVAL;
+
+ eventfd = eventfd_ctx_fdget(config->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ mutex_lock(&dm->ioeventfds_lock);
+
+ list_for_each_entry(p, &dm->ioeventfds, list) {
+ if (p->eventfd != eventfd)
+ continue;
+
+ /* Remove the associated client I/O range */
+ bao_io_client_range_del(dm->ioeventfd_client,
+ p->addr, p->addr + p->length - 1);
+
+ /* Shutdown and free the ioeventfd */
+ bao_ioeventfd_shutdown(dm, p);
+ break;
+ }
+
+ mutex_unlock(&dm->ioeventfds_lock);
+ eventfd_ctx_put(eventfd);
+
+ return 0;
+}
+
+/**
+ * bao_ioeventfd_handler - Handle an Ioeventfd client I/O request
+ * @client: Ioeventfd client associated with the request
+ * @req: I/O request to process
+ *
+ * Processes I/O requests from the Bao I/O client kernel thread
+ * (bao_io_client_kernel_thread). For READ operations, the value is
+ * ignored and set to 0 since virtio MMIO drivers only write to the
+ * `QueueNotify` field. WRITE operations are checked against the
+ * registered ioeventfds, and the corresponding eventfd is signaled
+ * if a match is found.
+ *
+ * Returns 0 on success.
+ */
+static int bao_ioeventfd_handler(struct bao_io_client *client,
+ struct bao_virtio_request *req)
+{
+ struct ioeventfd *p;
+
+ if (WARN_ON_ONCE(!client || !req))
+ return -EINVAL;
+
+ /* Handle read requests: just return 0 */
+ if (req->op == BAO_IO_READ) {
+ req->value = 0;
+ return 0;
+ }
+
+ /* Handle write requests */
+ mutex_lock(&client->dm->ioeventfds_lock);
+
+ p = bao_ioeventfd_match(client->dm, req->addr, req->value,
+ req->access_width);
+ if (p)
+ eventfd_signal(p->eventfd);
+
+ mutex_unlock(&client->dm->ioeventfds_lock);
+
+ return 0;
+}
+
+int bao_ioeventfd_client_config(struct bao_dm *dm, struct bao_ioeventfd *config)
+{
+ if (WARN_ON_ONCE(!dm || !config))
+ return -EINVAL;
+
+ if (config->flags & BAO_IOEVENTFD_FLAG_DEASSIGN)
+ bao_ioeventfd_deassign(dm, config);
+
+ return bao_ioeventfd_assign(dm, config);
+}
+
+int bao_ioeventfd_client_init(struct bao_dm *dm)
+{
+ char name[BAO_NAME_MAX_LEN];
+
+ if (WARN_ON_ONCE(!dm))
+ return -EINVAL;
+
+ mutex_init(&dm->ioeventfds_lock);
+ INIT_LIST_HEAD(&dm->ioeventfds);
+
+ snprintf(name, sizeof(name), "bao-ioevfdc%u", dm->info.id);
+
+ dm->ioeventfd_client = bao_io_client_create(dm, bao_ioeventfd_handler,
+ NULL, false, name);
+ if (!dm->ioeventfd_client)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void bao_ioeventfd_client_destroy(struct bao_dm *dm)
+{
+ struct ioeventfd *p, *next;
+
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ mutex_lock(&dm->ioeventfds_lock);
+ list_for_each_entry_safe(p, next, &dm->ioeventfds, list)
+ bao_ioeventfd_shutdown(dm, p);
+ mutex_unlock(&dm->ioeventfds_lock);
+}
diff --git a/drivers/virt/bao/io-dispatcher/irqfd.c b/drivers/virt/bao/io-dispatcher/irqfd.c
new file mode 100644
index 000000000000..145ed7428d9c
--- /dev/null
+++ b/drivers/virt/bao/io-dispatcher/irqfd.c
@@ -0,0 +1,341 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Bao Hypervisor Irqfd Server
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#include <linux/eventfd.h>
+#include <linux/file.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include "hypercall.h"
+
+#include "bao_drv.h"
+
+/**
+ * struct irqfd - Properties of an IRQ eventfd
+ * @dm: Associated Bao device model
+ * @wait: Wait queue entry for blocking/waking
+ * @shutdown: Work struct for async shutdown
+ * @eventfd: Eventfd used to signal interrupts
+ * @list: List node within &bao_dm.irqfds
+ * @pt: Poll table for select/poll on the eventfd
+ *
+ * Represents an IRQ eventfd registered to a Bao device model.
+ */
+struct irqfd {
+ struct bao_dm *dm;
+ wait_queue_entry_t wait;
+ struct work_struct shutdown;
+ struct eventfd_ctx *eventfd;
+ struct list_head list;
+ poll_table pt;
+};
+
+/**
+ * bao_irqfd_shutdown - Release and remove an irqfd
+ * @irqfd: IRQ eventfd to shut down (lock must be held)
+ *
+ * Removes the irqfd from the DM list, unregisters it from the
+ * eventfd wait queue, releases the eventfd, and frees the struct.
+ */
+static void bao_irqfd_shutdown(struct irqfd *irqfd)
+{
+ u64 cnt;
+
+ if (WARN_ON_ONCE(!irqfd || !irqfd->dm))
+ return;
+
+ lockdep_assert_held(&irqfd->dm->irqfds_lock);
+
+ /* Remove from DM list */
+ list_del_init(&irqfd->list);
+
+ /* Remove wait queue from eventfd context */
+ eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
+
+ /* Release the eventfd context */
+ eventfd_ctx_put(irqfd->eventfd);
+
+ /* Free irqfd structure */
+ kfree(irqfd);
+}
+
+/**
+ * bao_irqfd_inject - Inject a notify hypercall into the Bao hypervisor
+ * @id: Bao DM ID
+ *
+ * Sends a BAO_IO_NOTIFY hypercall to the hypervisor for the specified DM.
+ *
+ * Returns 0 on success or -EFAULT if the hypercall fails.
+ */
+static int bao_irqfd_inject(int id)
+{
+ struct bao_virtio_request request = {
+ .dm_id = id,
+ .addr = 0,
+ .op = BAO_IO_NOTIFY,
+ .value = 0,
+ .access_width = 0,
+ .request_id = 0,
+ };
+ struct remio_hypercall_ret ret;
+
+ ret = bao_hypercall_remio(&request);
+ if (ret.hyp_ret != 0 || ret.remio_hyp_ret != 0)
+ return -EFAULT;
+
+ return 0;
+}
+
+/**
+ * bao_irqfd_wakeup - Custom wake-up handler for eventfd signaling
+ * @wait: Wait queue entry
+ * @mode: Mode flags
+ * @sync: Sync indicator
+ * @key: Poll bits (cast from void *)
+ *
+ * Called by the Linux kernel poll table when the underlying eventfd is signaled.
+ * Injects a Bao notify hypercall on POLLIN or schedules shutdown on POLLHUP.
+ *
+ * Returns 0.
+ */
+static int bao_irqfd_wakeup(wait_queue_entry_t *wait, unsigned int mode,
+ int sync, void *key)
+{
+ struct irqfd *irqfd;
+ struct bao_dm *dm;
+ unsigned long poll_bits;
+
+ if (WARN_ON_ONCE(!wait || !key))
+ return -EINVAL;
+
+ irqfd = container_of(wait, struct irqfd, wait);
+ dm = irqfd->dm;
+ poll_bits = (unsigned long)key;
+
+ /* Inject IRQ on POLLIN */
+ if (poll_bits & POLLIN)
+ bao_irqfd_inject(dm->info.id);
+
+ /* Schedule shutdown on POLLHUP */
+ if (poll_bits & POLLHUP)
+ queue_work(dm->irqfd_server, &irqfd->shutdown);
+
+ return 0;
+}
+
+/**
+ * bao_irqfd_poll_func - Register an IRQFD with a poll table
+ * @file: File to poll
+ * @wqh: Wait queue head
+ * @pt: Poll table
+ *
+ * Adds the irqfd's wait queue entry to the kernel wait queue for event monitoring.
+ */
+static void bao_irqfd_poll_func(struct file *file, wait_queue_head_t *wqh,
+ poll_table *pt)
+{
+ struct irqfd *irqfd;
+
+ if (WARN_ON_ONCE(!pt || !wqh))
+ return;
+
+ irqfd = container_of(pt, struct irqfd, pt);
+ add_wait_queue(wqh, &irqfd->wait);
+}
+
+/**
+ * irqfd_shutdown_work - Workqueue handler to shutdown an irqfd
+ * @work: Work struct for the shutdown operation
+ *
+ * Removes and frees the irqfd from the DM under lock if it is still linked.
+ */
+static void irqfd_shutdown_work(struct work_struct *work)
+{
+ struct irqfd *irqfd;
+ struct bao_dm *dm;
+
+ if (WARN_ON_ONCE(!work))
+ return;
+
+ irqfd = container_of(work, struct irqfd, shutdown);
+ dm = irqfd->dm;
+
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ mutex_lock(&dm->irqfds_lock);
+ if (!list_empty(&irqfd->list))
+ bao_irqfd_shutdown(irqfd);
+ mutex_unlock(&dm->irqfds_lock);
+}
+
+/**
+ * bao_irqfd_assign - Assign an eventfd to a DM and create an irqfd
+ * @dm: Bao device model to assign the eventfd
+ * @args: Configuration of the irqfd to assign
+ *
+ * Allocates and initializes an irqfd for the given eventfd, registers
+ * it with the DM, sets up the wait queue and poll table, and triggers
+ * an initial notify if the eventfd is already signaled.
+ *
+ * Returns 0 on success or a negative error code on failure:
+ * -ENOMEM if allocation fails
+ * -EBADF if the file descriptor is invalid
+ * -EBUSY if an irqfd with the same eventfd already exists
+ * Other negative values may be returned by eventfd_ctx_fileget().
+ */
+static int bao_irqfd_assign(struct bao_dm *dm, struct bao_irqfd *args)
+{
+ struct eventfd_ctx *eventfd = NULL;
+ struct irqfd *irqfd, *tmp;
+ __poll_t events;
+ struct fd f;
+ int ret = 0;
+
+ if (WARN_ON_ONCE(!dm || !args))
+ return -EINVAL;
+
+ irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
+ if (!irqfd)
+ return -ENOMEM;
+
+ irqfd->dm = dm;
+ INIT_LIST_HEAD(&irqfd->list);
+ INIT_WORK(&irqfd->shutdown, irqfd_shutdown_work);
+
+ /* Get the file descriptor and associated eventfd context */
+ f = fdget(args->fd);
+ if (!fd_file(f)) {
+ ret = -EBADF;
+ goto out_free_irqfd;
+ }
+
+ eventfd = eventfd_ctx_fileget(fd_file(f));
+ if (IS_ERR(eventfd)) {
+ ret = PTR_ERR(eventfd);
+ goto out_fdput;
+ }
+ irqfd->eventfd = eventfd;
+
+ /* Initialize wait queue and poll table for this irqfd */
+ init_waitqueue_func_entry(&irqfd->wait, bao_irqfd_wakeup);
+ init_poll_funcptr(&irqfd->pt, bao_irqfd_poll_func);
+
+ /* Check for conflicts with existing irqfds */
+ mutex_lock(&dm->irqfds_lock);
+ list_for_each_entry(tmp, &dm->irqfds, list) {
+ if (irqfd->eventfd == tmp->eventfd) {
+ ret = -EBUSY;
+ mutex_unlock(&dm->irqfds_lock);
+ goto out_put_eventfd;
+ }
+ }
+ list_add_tail(&irqfd->list, &dm->irqfds);
+ mutex_unlock(&dm->irqfds_lock);
+
+ /* Trigger initial notification if the eventfd is already signaled */
+ events = vfs_poll(fd_file(f), &irqfd->pt);
+ if (events & EPOLLIN)
+ bao_irqfd_inject(dm->info.id);
+
+ fdput(f);
+ return 0;
+
+out_put_eventfd:
+ eventfd_ctx_put(eventfd);
+out_fdput:
+ fdput(f);
+out_free_irqfd:
+ kfree(irqfd);
+ return ret;
+}
+
+/**
+ * bao_irqfd_deassign - Deassign an eventfd and destroy the associated irqfd
+ * @dm: Bao device model to remove the irqfd from
+ * @args: Configuration of the irqfd to deassign
+ *
+ * Finds the irqfd associated with the given eventfd in the DM,
+ * shuts it down, and releases the eventfd context.
+ *
+ * Returns 0 on success or a negative error code if the eventfd lookup fails.
+ */
+static int bao_irqfd_deassign(struct bao_dm *dm, struct bao_irqfd *args)
+{
+ struct irqfd *irqfd, *tmp;
+ struct eventfd_ctx *eventfd;
+
+ if (WARN_ON_ONCE(!dm || !args))
+ return -EINVAL;
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ mutex_lock(&dm->irqfds_lock);
+ list_for_each_entry_safe(irqfd, tmp, &dm->irqfds, list) {
+ if (irqfd->eventfd == eventfd) {
+ bao_irqfd_shutdown(irqfd);
+ break;
+ }
+ }
+ mutex_unlock(&dm->irqfds_lock);
+
+ eventfd_ctx_put(eventfd);
+
+ return 0;
+}
+
+int bao_irqfd_server_config(struct bao_dm *dm, struct bao_irqfd *config)
+{
+ if (WARN_ON_ONCE(!dm || !config))
+ return -EINVAL;
+
+ if (config->flags & BAO_IRQFD_FLAG_DEASSIGN)
+ return bao_irqfd_deassign(dm, config);
+
+ return bao_irqfd_assign(dm, config);
+}
+
+int bao_irqfd_server_init(struct bao_dm *dm)
+{
+ char name[BAO_NAME_MAX_LEN];
+
+ if (WARN_ON_ONCE(!dm))
+ return -EINVAL;
+
+ mutex_init(&dm->irqfds_lock);
+ INIT_LIST_HEAD(&dm->irqfds);
+
+ snprintf(name, sizeof(name), "bao-ioirqfds%u", dm->info.id);
+
+ dm->irqfd_server = alloc_workqueue(name, WQ_UNBOUND | WQ_HIGHPRI, 0);
+ if (!dm->irqfd_server)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void bao_irqfd_server_destroy(struct bao_dm *dm)
+{
+ struct irqfd *irqfd, *next;
+
+ if (WARN_ON_ONCE(!dm))
+ return;
+
+ if (dm->irqfd_server)
+ destroy_workqueue(dm->irqfd_server);
+
+ mutex_lock(&dm->irqfds_lock);
+ list_for_each_entry_safe(irqfd, next, &dm->irqfds, list)
+ bao_irqfd_shutdown(irqfd);
+ mutex_unlock(&dm->irqfds_lock);
+}
diff --git a/include/uapi/linux/bao.h b/include/uapi/linux/bao.h
new file mode 100644
index 000000000000..581b094861ce
--- /dev/null
+++ b/include/uapi/linux/bao.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Provides the Bao Hypervisor IOCTLs and global structures
+ *
+ * Copyright (c) Bao Project and Contributors. All rights reserved.
+ *
+ * Authors:
+ * João Peixoto <joaopeixoto@...x.tech>
+ * José Martins <jose@...x.tech>
+ * David Cerdeira <davidmcerdeira@...x.tech>
+ */
+
+#ifndef _UAPI_BAO_H
+#define _UAPI_BAO_H
+
+#include <linux/types.h>
+#include <linux/uuid.h>
+#include <linux/list.h>
+
+#define BAO_IO_WRITE 0x0
+#define BAO_IO_READ 0x1
+#define BAO_IO_ASK 0x2
+#define BAO_IO_NOTIFY 0x3
+
+#define BAO_NAME_MAX_LEN 16
+#define BAO_IO_REQUEST_MAX 64
+#define BAO_IO_MAX_DMS 16
+
+/**
+ * struct bao_virtio_request - Parameters of a Bao VirtIO request
+ * @dm_id: Device model ID
+ * @addr: MMIO register address accessed
+ * @op: Operation type (WRITE, READ, ASK, NOTIFY)
+ * @value: Value to write or read
+ * @access_width: Access width (VirtIO MMIO supports 4-byte aligned accesses)
+ * @request_id: Request ID of the I/O request
+ */
+struct bao_virtio_request {
+ __u64 dm_id;
+ __u64 addr;
+ __u64 op;
+ __u64 value;
+ __u64 access_width;
+ __u64 request_id;
+};
+
+/**
+ * struct bao_ioeventfd - Parameters of an ioeventfd request
+ * @fd: Eventfd file descriptor associated with the I/O request
+ * @flags: Logical OR of BAO_IOEVENTFD_FLAG_*
+ * @addr: Start address of the I/O range
+ * @len: Length of the I/O range
+ * @reserved: Reserved, must be 0
+ * @data: Data for matching (used if data matching is enabled)
+ */
+struct bao_ioeventfd {
+ __u32 fd;
+ __u32 flags;
+ __u64 addr;
+ __u32 len;
+ __u32 reserved;
+ __u64 data;
+};
+
+/**
+ * struct bao_irqfd - Parameters of an IRQFD request
+ * @fd: File descriptor of the eventfd
+ * @flags: Flags associated with the eventfd
+ */
+struct bao_irqfd {
+ __s32 fd;
+ __u32 flags;
+};
+
+/**
+ * struct bao_dm_info - Parameters of a Bao device model
+ * @id: Virtual ID of the DM
+ * @shmem_addr: Base address of the shared memory
+ * @shmem_size: Size of the shared memory
+ * @irq: IRQ number
+ * @fd: File descriptor of the DM
+ */
+struct bao_dm_info {
+ __u32 id;
+ __u64 shmem_addr;
+ __u64 shmem_size;
+ __u32 irq;
+ __s32 fd;
+};
+
+/*
+ * The ioctl type for Bao, documented in
+ * Documentation/userspace-api/ioctl/ioctl-number.rst
+ */
+#define BAO_IOCTL_TYPE 0xA6
+
+/*
+ * Bao userspace IOCTL commands
+ * Follows Linux kernel convention, see Documentation/driver-api/ioctl.rst
+ */
+#define BAO_IOCTL_DM_GET_INFO _IOWR(BAO_IOCTL_TYPE, 0x01, struct bao_dm_info)
+#define BAO_IOCTL_IO_CLIENT_ATTACH \
+ _IOWR(BAO_IOCTL_TYPE, 0x02, struct bao_virtio_request)
+#define BAO_IOCTL_IO_REQUEST_COMPLETE \
+ _IOW(BAO_IOCTL_TYPE, 0x03, struct bao_virtio_request)
+#define BAO_IOCTL_IOEVENTFD _IOW(BAO_IOCTL_TYPE, 0x04, struct bao_ioeventfd)
+#define BAO_IOCTL_IRQFD _IOW(BAO_IOCTL_TYPE, 0x05, struct bao_irqfd)
+
+/* Remote I/O Hypercall ID */
+#define REMIO_HC_ID 0x2
+
+/**
+ * struct remio_hypercall_ret - Remote I/O hypercall return values
+ * @hyp_ret: Generic return value from the Bao hypercall
+ * @remio_hyp_ret: Remote I/O–specific return value
+ * @pending_requests: Number of pending requests (only for Remote I/O Ask hypercall)
+ */
+struct remio_hypercall_ret {
+ u64 hyp_ret;
+ u64 remio_hyp_ret;
+ u64 pending_requests;
+};
+
+#endif /* _UAPI_BAO_H */
--
2.43.0
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