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Message-Id: <1605918637-12192-5-git-send-email-nunodasneves@linux.microsoft.com>
Date: Fri, 20 Nov 2020 16:30:23 -0800
From: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To: linux-hyperv@...r.kernel.org
Cc: virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, mikelley@...rosoft.com,
viremana@...ux.microsoft.com, sunilmut@...rosoft.com,
nunodasneves@...ux.microsoft.com, wei.liu@...nel.org,
ligrassi@...rosoft.com, kys@...rosoft.com
Subject: [RFC PATCH 04/18] virt/mshv: request version ioctl
Reserve ioctl number in userpsace-api/ioctl/ioctl-number.rst
Introduce MSHV_REQUEST_VERSION ioctl.
Introduce documentation for /dev/mshv in Documentation/virt/mshv
Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
---
.../userspace-api/ioctl/ioctl-number.rst | 2 +
Documentation/virt/mshv/api.rst | 62 +++++++++++++++++++
include/linux/mshv.h | 11 ++++
include/uapi/linux/mshv.h | 19 ++++++
virt/mshv/mshv_main.c | 49 +++++++++++++++
5 files changed, 143 insertions(+)
create mode 100644 Documentation/virt/mshv/api.rst
create mode 100644 include/linux/mshv.h
create mode 100644 include/uapi/linux/mshv.h
diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 55a2d9b2ce33..13a4d3ecafca 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -343,6 +343,8 @@ Code Seq# Include File Comments
0xB5 00-0F uapi/linux/rpmsg.h <mailto:linux-remoteproc@...r.kernel.org>
0xB6 all linux/fpga-dfl.h
0xB7 all uapi/linux/remoteproc_cdev.h <mailto:linux-remoteproc@...r.kernel.org>
+0xB8 all uapi/linux/mshv.h Microsoft Hypervisor root partition APIs
+ <mailto:linux-hyperv@...r.kernel.org>
0xC0 00-0F linux/usb/iowarrior.h
0xCA 00-0F uapi/misc/cxl.h
0xCA 10-2F uapi/misc/ocxl.h
diff --git a/Documentation/virt/mshv/api.rst b/Documentation/virt/mshv/api.rst
new file mode 100644
index 000000000000..82e32de48d03
--- /dev/null
+++ b/Documentation/virt/mshv/api.rst
@@ -0,0 +1,62 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================================================
+Microsoft Hypervisor Root Partition API Documentation
+=====================================================
+
+1. Overview
+===========
+
+This document describes APIs for creating and managing guest virtual machines
+when running Linux as the root partition on the Microsoft Hypervisor.
+
+This API is not yet stable.
+
+2. Glossary/Terms
+=================
+
+hv
+--
+Short for Hyper-V. This name is used in the kernel to describe interfaces to
+the Microsoft Hypervisor.
+
+mshv
+----
+Short for Microsoft Hypervisor. This is the name of the userland API module
+described in this document.
+
+Partition
+---------
+A virtual machine running on the Microsoft Hypervisor.
+
+Root Partition
+--------------
+The partition that is created and assumes control when the machine boots. The
+root partition can use mshv APIs to create guest partitions.
+
+3. API description
+==================
+
+The module is named mshv and can be configured with CONFIG_HYPERV_ROOT_API.
+
+Mshv is file descriptor-based, following a similar pattern to KVM.
+
+To get a handle to the mshv driver, use open("/dev/mshv").
+
+3.1 MSHV_REQUEST_VERSION
+------------------------
+:Type: /dev/mshv ioctl
+:Parameters: pointer to a u32
+:Returns: 0 on success
+
+Before issuing any other ioctls, a MSHV_REQUEST_VERSION ioctl must be called to
+establish the interface version with the kernel module.
+
+The caller should pass the MSHV_VERSION as an argument.
+
+The kernel module will check which interface versions it supports and return 0
+if one of them matches.
+
+This /dev/mshv file descriptor will remain 'locked' to that version as long as
+it is open - this ioctl can only be called once per open.
+
diff --git a/include/linux/mshv.h b/include/linux/mshv.h
new file mode 100644
index 000000000000..a0982fe2c0b8
--- /dev/null
+++ b/include/linux/mshv.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _LINUX_MSHV_H
+#define _LINUX_MSHV_H
+
+/*
+ * Microsoft Hypervisor root partition driver for /dev/mshv
+ */
+
+#include <uapi/linux/mshv.h>
+
+#endif
diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h
new file mode 100644
index 000000000000..dd30fc2f0a80
--- /dev/null
+++ b/include/uapi/linux/mshv.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_MSHV_H
+#define _UAPI_LINUX_MSHV_H
+
+/*
+ * Userspace interface for /dev/mshv
+ * Microsoft Hypervisor root partition APIs
+ */
+
+#include <linux/types.h>
+
+#define MSHV_VERSION 0x0
+
+#define MSHV_IOCTL 0xB8
+
+/* mshv device */
+#define MSHV_REQUEST_VERSION _IOW(MSHV_IOCTL, 0x00, __u32)
+
+#endif
diff --git a/virt/mshv/mshv_main.c b/virt/mshv/mshv_main.c
index ecb9089761fe..62f631f85301 100644
--- a/virt/mshv/mshv_main.c
+++ b/virt/mshv/mshv_main.c
@@ -11,25 +11,74 @@
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
+#include <linux/slab.h>
+#include <linux/mshv.h>
MODULE_AUTHOR("Microsoft");
MODULE_LICENSE("GPL");
+#define MSHV_INVALID_VERSION 0xFFFFFFFF
+#define MSHV_CURRENT_VERSION MSHV_VERSION
+
+static u32 supported_versions[] = {
+ MSHV_CURRENT_VERSION,
+};
+
+static long
+mshv_ioctl_request_version(u32 *version, void __user *user_arg)
+{
+ u32 arg;
+ int i;
+
+ if (copy_from_user(&arg, user_arg, sizeof(arg)))
+ return -EFAULT;
+
+ for (i = 0; i < ARRAY_SIZE(supported_versions); ++i) {
+ if (supported_versions[i] == arg) {
+ *version = supported_versions[i];
+ return 0;
+ }
+ }
+ return -ENOTSUPP;
+}
+
static long
mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
{
+ u32 *version = (u32 *)filp->private_data;
+
+ if (ioctl == MSHV_REQUEST_VERSION) {
+ /* Version can only be set once */
+ if (*version != MSHV_INVALID_VERSION)
+ return -EBADFD;
+
+ return mshv_ioctl_request_version(version, (void __user *)arg);
+ }
+
+ /* Version must be set before other ioctls can be called */
+ if (*version == MSHV_INVALID_VERSION)
+ return -EBADFD;
+
+ /* TODO other ioctls */
+
return -ENOTTY;
}
static int
mshv_dev_open(struct inode *inode, struct file *filp)
{
+ filp->private_data = kmalloc(sizeof(u32), GFP_KERNEL);
+ if (!filp->private_data)
+ return -ENOMEM;
+ *(u32 *)filp->private_data = MSHV_INVALID_VERSION;
+
return 0;
}
static int
mshv_dev_release(struct inode *inode, struct file *filp)
{
+ kfree(filp->private_data);
return 0;
}
--
2.25.1
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