Message-Id: <f833e77685cd1dfadc5c3b6688d29a0d1383dbb9.1631621507.git.wuzongyong@linux.alibaba.com>
Date:   Tue, 14 Sep 2021 20:24:48 +0800
From:   Wu Zongyong <wuzongyong@...ux.alibaba.com>
To:     wuzongyong@...ux.alibaba.com, jasowang@...hat.com,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, mst@...hat.com
Cc:     wei.yang1@...ux.alibaba.com
Subject: [PATCH v2 1/5] virtio-pci: introduce legacy device module

Split common codes from virtio-pci-legacy so vDPA driver can reuse it
later.

Signed-off-by: Wu Zongyong <wuzongyong@...ux.alibaba.com>
---
 drivers/virtio/Kconfig                 |  10 ++
 drivers/virtio/Makefile                |   1 +
 drivers/virtio/virtio_pci_common.c     |  10 +-
 drivers/virtio/virtio_pci_common.h     |   9 +-
 drivers/virtio/virtio_pci_legacy.c     | 101 +++---------
 drivers/virtio/virtio_pci_legacy_dev.c | 220 +++++++++++++++++++++++++
 include/linux/virtio_pci_legacy.h      |  44 +++++
 7 files changed, 312 insertions(+), 83 deletions(-)
 create mode 100644 drivers/virtio/virtio_pci_legacy_dev.c
 create mode 100644 include/linux/virtio_pci_legacy.h

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index ce1b3f6ec325..b14768dc9e04 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -20,6 +20,15 @@ config VIRTIO_PCI_LIB
 	  PCI device with possible vendor specific extensions. Any
 	  module that selects this module must depend on PCI.
 
+config VIRTIO_PCI_LIB_LEGACY
+	tristate
+	help
+	  Legacy PCI device (Virtio PCI Card 0.9.x Draft and older device)
+	  implementation.
+	  This modules implements the basic probe and control for devices
+	  which are based on legacy PCI device. Any module that selects this
+	  module must depend on PCI.
+
 menuconfig VIRTIO_MENU
 	bool "Virtio drivers"
 	default y
@@ -43,6 +52,7 @@ config VIRTIO_PCI_LEGACY
 	bool "Support for legacy virtio draft 0.9.X and older devices"
 	default y
 	depends on VIRTIO_PCI
+	select VIRTIO_PCI_LIB_LEGACY
 	help
           Virtio PCI Card 0.9.X Draft (circa 2014) and older device support.
 
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 699bbea0465f..0a82d0873248 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o
 obj-$(CONFIG_VIRTIO_PCI_LIB) += virtio_pci_modern_dev.o
+obj-$(CONFIG_VIRTIO_PCI_LIB_LEGACY) += virtio_pci_legacy_dev.o
 obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
 obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
 virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index b35bb2d57f62..d724f676608b 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -549,6 +549,8 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
 
 	pci_set_master(pci_dev);
 
+	vp_dev->is_legacy = vp_dev->ldev.ioaddr ? true : false;
+
 	rc = register_virtio_device(&vp_dev->vdev);
 	reg_dev = vp_dev;
 	if (rc)
@@ -557,10 +559,10 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
 	return 0;
 
 err_register:
-	if (vp_dev->ioaddr)
-	     virtio_pci_legacy_remove(vp_dev);
+	if (vp_dev->is_legacy)
+		virtio_pci_legacy_remove(vp_dev);
 	else
-	     virtio_pci_modern_remove(vp_dev);
+		virtio_pci_modern_remove(vp_dev);
 err_probe:
 	pci_disable_device(pci_dev);
 err_enable_device:
@@ -587,7 +589,7 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
 
 	unregister_virtio_device(&vp_dev->vdev);
 
-	if (vp_dev->ioaddr)
+	if (vp_dev->is_legacy)
 		virtio_pci_legacy_remove(vp_dev);
 	else
 		virtio_pci_modern_remove(vp_dev);
diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
index beec047a8f8d..eb17a29fc7ef 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -25,6 +25,7 @@
 #include <linux/virtio_config.h>
 #include <linux/virtio_ring.h>
 #include <linux/virtio_pci.h>
+#include <linux/virtio_pci_legacy.h>
 #include <linux/virtio_pci_modern.h>
 #include <linux/highmem.h>
 #include <linux/spinlock.h>
@@ -44,16 +45,14 @@ struct virtio_pci_vq_info {
 struct virtio_pci_device {
 	struct virtio_device vdev;
 	struct pci_dev *pci_dev;
+	struct virtio_pci_legacy_device ldev;
 	struct virtio_pci_modern_device mdev;
 
-	/* In legacy mode, these two point to within ->legacy. */
+	bool is_legacy;
+
 	/* Where to read and clear interrupt */
 	u8 __iomem *isr;
 
-	/* Legacy only field */
-	/* the IO mapping for the PCI config space */
-	void __iomem *ioaddr;
-
 	/* a list of queues so we can dispatch IRQs */
 	spinlock_t lock;
 	struct list_head virtqueues;
diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
index d62e9835aeec..82eb437ad920 100644
--- a/drivers/virtio/virtio_pci_legacy.c
+++ b/drivers/virtio/virtio_pci_legacy.c
@@ -14,6 +14,7 @@
  *  Michael S. Tsirkin <mst@...hat.com>
  */
 
+#include "linux/virtio_pci_legacy.h"
 #include "virtio_pci_common.h"
 
 /* virtio config->get_features() implementation */
@@ -23,7 +24,7 @@ static u64 vp_get_features(struct virtio_device *vdev)
 
 	/* When someone needs more than 32 feature bits, we'll need to
 	 * steal a bit to indicate that the rest are somewhere else. */
-	return ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
+	return vp_legacy_get_features(&vp_dev->ldev);
 }
 
 /* virtio config->finalize_features() implementation */
@@ -38,7 +39,7 @@ static int vp_finalize_features(struct virtio_device *vdev)
 	BUG_ON((u32)vdev->features != vdev->features);
 
 	/* We only support 32 feature bits. */
-	iowrite32(vdev->features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+	vp_legacy_set_features(&vp_dev->ldev, vdev->features);
 
 	return 0;
 }
@@ -48,7 +49,7 @@ static void vp_get(struct virtio_device *vdev, unsigned offset,
 		   void *buf, unsigned len)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-	void __iomem *ioaddr = vp_dev->ioaddr +
+	void __iomem *ioaddr = vp_dev->ldev.ioaddr +
 			VIRTIO_PCI_CONFIG_OFF(vp_dev->msix_enabled) +
 			offset;
 	u8 *ptr = buf;
@@ -64,7 +65,7 @@ static void vp_set(struct virtio_device *vdev, unsigned offset,
 		   const void *buf, unsigned len)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-	void __iomem *ioaddr = vp_dev->ioaddr +
+	void __iomem *ioaddr = vp_dev->ldev.ioaddr +
 			VIRTIO_PCI_CONFIG_OFF(vp_dev->msix_enabled) +
 			offset;
 	const u8 *ptr = buf;
@@ -78,7 +79,7 @@ static void vp_set(struct virtio_device *vdev, unsigned offset,
 static u8 vp_get_status(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-	return ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	return vp_legacy_get_status(&vp_dev->ldev);
 }
 
 static void vp_set_status(struct virtio_device *vdev, u8 status)
@@ -86,28 +87,24 @@ static void vp_set_status(struct virtio_device *vdev, u8 status)
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	/* We should never be setting status to 0. */
 	BUG_ON(status == 0);
-	iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	vp_legacy_set_status(&vp_dev->ldev, status);
 }
 
 static void vp_reset(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	/* 0 status means a reset. */
-	iowrite8(0, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	vp_legacy_set_status(&vp_dev->ldev, 0);
 	/* Flush out the status write, and flush in device writes,
 	 * including MSi-X interrupts, if any. */
-	ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+	vp_legacy_get_status(&vp_dev->ldev);
 	/* Flush pending VQ/configuration callbacks. */
 	vp_synchronize_vectors(vdev);
 }
 
 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
 {
-	/* Setup the vector used for configuration events */
-	iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
-	/* Verify we had enough resources to assign the vector */
-	/* Will also flush the write out to device */
-	return ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+	return vp_legacy_config_vector(&vp_dev->ldev, vector);
 }
 
 static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
@@ -123,12 +120,9 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
 	int err;
 	u64 q_pfn;
 
-	/* Select the queue we're interested in */
-	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
-
 	/* Check if queue is either not available or already active. */
-	num = ioread16(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NUM);
-	if (!num || ioread32(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN))
+	num = vp_legacy_get_queue_size(&vp_dev->ldev, index);
+	if (!num || vp_legacy_get_queue_enable(&vp_dev->ldev, index))
 		return ERR_PTR(-ENOENT);
 
 	info->msix_vector = msix_vec;
@@ -151,13 +145,12 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
 	}
 
 	/* activate the queue */
-	iowrite32(q_pfn, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+	vp_legacy_set_queue_address(&vp_dev->ldev, index, q_pfn);
 
-	vq->priv = (void __force *)vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
+	vq->priv = (void __force *)vp_dev->ldev.ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
 
 	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
-		iowrite16(msix_vec, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
-		msix_vec = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+		msix_vec = vp_legacy_queue_vector(&vp_dev->ldev, index, msix_vec);
 		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
 			err = -EBUSY;
 			goto out_deactivate;
@@ -167,7 +160,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
 	return vq;
 
 out_deactivate:
-	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+	vp_legacy_set_queue_address(&vp_dev->ldev, index, 0);
 out_del_vq:
 	vring_del_virtqueue(vq);
 	return ERR_PTR(err);
@@ -178,17 +171,15 @@ static void del_vq(struct virtio_pci_vq_info *info)
 	struct virtqueue *vq = info->vq;
 	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
 
-	iowrite16(vq->index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
-
 	if (vp_dev->msix_enabled) {
-		iowrite16(VIRTIO_MSI_NO_VECTOR,
-			  vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+		vp_legacy_queue_vector(&vp_dev->ldev, vq->index,
+				VIRTIO_MSI_NO_VECTOR);
 		/* Flush the write out to device */
-		ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
+		ioread8(vp_dev->ldev.ioaddr + VIRTIO_PCI_ISR);
 	}
 
 	/* Select and deactivate the queue */
-	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+	vp_legacy_set_queue_address(&vp_dev->ldev, vq->index, 0);
 
 	vring_del_virtqueue(vq);
 }
@@ -211,51 +202,18 @@ static const struct virtio_config_ops virtio_pci_config_ops = {
 /* the PCI probing function */
 int virtio_pci_legacy_probe(struct virtio_pci_device *vp_dev)
 {
+	struct virtio_pci_legacy_device *ldev = &vp_dev->ldev;
 	struct pci_dev *pci_dev = vp_dev->pci_dev;
 	int rc;
 
-	/* We only own devices >= 0x1000 and <= 0x103f: leave the rest. */
-	if (pci_dev->device < 0x1000 || pci_dev->device > 0x103f)
-		return -ENODEV;
-
-	if (pci_dev->revision != VIRTIO_PCI_ABI_VERSION) {
-		printk(KERN_ERR "virtio_pci: expected ABI version %d, got %d\n",
-		       VIRTIO_PCI_ABI_VERSION, pci_dev->revision);
-		return -ENODEV;
-	}
-
-	rc = dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(64));
-	if (rc) {
-		rc = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(32));
-	} else {
-		/*
-		 * The virtio ring base address is expressed as a 32-bit PFN,
-		 * with a page size of 1 << VIRTIO_PCI_QUEUE_ADDR_SHIFT.
-		 */
-		dma_set_coherent_mask(&pci_dev->dev,
-				DMA_BIT_MASK(32 + VIRTIO_PCI_QUEUE_ADDR_SHIFT));
-	}
-
-	if (rc)
-		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
+	ldev->pci_dev = pci_dev;
 
-	rc = pci_request_region(pci_dev, 0, "virtio-pci-legacy");
+	rc = vp_legacy_probe(ldev);
 	if (rc)
 		return rc;
 
-	rc = -ENOMEM;
-	vp_dev->ioaddr = pci_iomap(pci_dev, 0, 0);
-	if (!vp_dev->ioaddr)
-		goto err_iomap;
-
-	vp_dev->isr = vp_dev->ioaddr + VIRTIO_PCI_ISR;
-
-	/* we use the subsystem vendor/device id as the virtio vendor/device
-	 * id.  this allows us to use the same PCI vendor/device id for all
-	 * virtio devices and to identify the particular virtio driver by
-	 * the subsystem ids */
-	vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
-	vp_dev->vdev.id.device = pci_dev->subsystem_device;
+	vp_dev->isr = ldev->isr;
+	vp_dev->vdev.id = ldev->id;
 
 	vp_dev->vdev.config = &virtio_pci_config_ops;
 
@@ -264,16 +222,11 @@ int virtio_pci_legacy_probe(struct virtio_pci_device *vp_dev)
 	vp_dev->del_vq = del_vq;
 
 	return 0;
-
-err_iomap:
-	pci_release_region(pci_dev, 0);
-	return rc;
 }
 
 void virtio_pci_legacy_remove(struct virtio_pci_device *vp_dev)
 {
-	struct pci_dev *pci_dev = vp_dev->pci_dev;
+	struct virtio_pci_legacy_device *ldev = &vp_dev->ldev;
 
-	pci_iounmap(pci_dev, vp_dev->ioaddr);
-	pci_release_region(pci_dev, 0);
+	vp_legacy_remove(ldev);
 }
diff --git a/drivers/virtio/virtio_pci_legacy_dev.c b/drivers/virtio/virtio_pci_legacy_dev.c
new file mode 100644
index 000000000000..9b97680dd02b
--- /dev/null
+++ b/drivers/virtio/virtio_pci_legacy_dev.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "linux/virtio_pci.h"
+#include <linux/virtio_pci_legacy.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+
+
+/*
+ * vp_legacy_probe: probe the legacy virtio pci device, note that the
+ * caller is required to enable PCI device before calling this function.
+ * @ldev: the legacy virtio-pci device
+ *
+ * Return 0 on succeed otherwise fail
+ */
+int vp_legacy_probe(struct virtio_pci_legacy_device *ldev)
+{
+	struct pci_dev *pci_dev = ldev->pci_dev;
+	int rc;
+
+	/* We only own devices >= 0x1000 and <= 0x103f: leave the rest. */
+	if (pci_dev->device < 0x1000 || pci_dev->device > 0x103f)
+		return -ENODEV;
+
+	if (pci_dev->revision != VIRTIO_PCI_ABI_VERSION)
+		return -ENODEV;
+
+	rc = dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(64));
+	if (rc) {
+		rc = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(32));
+	} else {
+		/*
+		 * The virtio ring base address is expressed as a 32-bit PFN,
+		 * with a page size of 1 << VIRTIO_PCI_QUEUE_ADDR_SHIFT.
+		 */
+		dma_set_coherent_mask(&pci_dev->dev,
+				DMA_BIT_MASK(32 + VIRTIO_PCI_QUEUE_ADDR_SHIFT));
+	}
+
+	if (rc)
+		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
+
+	rc = pci_request_region(pci_dev, 0, "virtio-pci-legacy");
+	if (rc)
+		return rc;
+
+	ldev->ioaddr = pci_iomap(pci_dev, 0, 0);
+	if (!ldev->ioaddr)
+		goto err_iomap;
+
+	ldev->isr = ldev->ioaddr + VIRTIO_PCI_ISR;
+
+	ldev->id.vendor = pci_dev->subsystem_vendor;
+	ldev->id.device = pci_dev->subsystem_device;
+
+	return 0;
+err_iomap:
+	pci_release_region(pci_dev, 0);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(vp_legacy_probe);
+
+/*
+ * vp_legacy_probe: remove and cleanup the legacy virtio pci device
+ * @ldev: the legacy virtio-pci device
+ */
+void vp_legacy_remove(struct virtio_pci_legacy_device *ldev)
+{
+	struct pci_dev *pci_dev = ldev->pci_dev;
+
+	pci_iounmap(pci_dev, ldev->ioaddr);
+	pci_release_region(pci_dev, 0);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_remove);
+
+/*
+ * vp_legacy_get_features - get features from device
+ * @ldev: the legacy virtio-pci device
+ *
+ * Returns the features read from the device
+ */
+u64 vp_legacy_get_features(struct virtio_pci_legacy_device *ldev)
+{
+
+	return ioread32(ldev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_get_features);
+
+/*
+ * vp_legacy_get_driver_features - get driver features from device
+ * @ldev: the legacy virtio-pci device
+ *
+ * Returns the driver features read from the device
+ */
+u64 vp_legacy_get_driver_features(struct virtio_pci_legacy_device *ldev)
+{
+	return ioread32(ldev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_get_driver_features);
+
+/*
+ * vp_legacy_set_features - set features to device
+ * @ldev: the legacy virtio-pci device
+ * @features: the features set to device
+ */
+void vp_legacy_set_features(struct virtio_pci_legacy_device *ldev,
+			    u32 features)
+{
+	iowrite32(features, ldev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_set_features);
+
+/*
+ * vp_legacy_get_status - get the device status
+ * @ldev: the legacy virtio-pci device
+ *
+ * Returns the status read from device
+ */
+u8 vp_legacy_get_status(struct virtio_pci_legacy_device *ldev)
+{
+	return ioread8(ldev->ioaddr + VIRTIO_PCI_STATUS);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_get_status);
+
+/*
+ * vp_legacy_set_status - set status to device
+ * @ldev: the legacy virtio-pci device
+ * @status: the status set to device
+ */
+void vp_legacy_set_status(struct virtio_pci_legacy_device *ldev,
+				 u8 status)
+{
+	iowrite8(status, ldev->ioaddr + VIRTIO_PCI_STATUS);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_set_status);
+
+/*
+ * vp_legacy_queue_vector - set the MSIX vector for a specific virtqueue
+ * @ldev: the legacy virtio-pci device
+ * @index: queue index
+ * @vector: the config vector
+ *
+ * Returns the config vector read from the device
+ */
+u16 vp_legacy_queue_vector(struct virtio_pci_legacy_device *ldev,
+			   u16 index, u16 vector)
+{
+	iowrite16(index, ldev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+	iowrite16(vector, ldev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+	/* Flush the write out to device */
+	return ioread16(ldev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_queue_vector);
+
+/*
+ * vp_legacy_config_vector - set the vector for config interrupt
+ * @ldev: the legacy virtio-pci device
+ * @vector: the config vector
+ *
+ * Returns the config vector read from the device
+ */
+u16 vp_legacy_config_vector(struct virtio_pci_legacy_device *ldev,
+			    u16 vector)
+{
+	/* Setup the vector used for configuration events */
+	iowrite16(vector, ldev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+	/* Verify we had enough resources to assign the vector */
+	/* Will also flush the write out to device */
+	return ioread16(ldev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_config_vector);
+
+/*
+ * vp_legacy_set_queue_address - set the virtqueue address
+ * @ldev: the legacy virtio-pci device
+ * @index: the queue index
+ * @queue_pfn: pfn of the virtqueue
+ */
+void vp_legacy_set_queue_address(struct virtio_pci_legacy_device *ldev,
+			     u16 index, u32 queue_pfn)
+{
+	iowrite16(index, ldev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+	iowrite32(queue_pfn, ldev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_set_queue_address);
+
+/*
+ * vp_legacy_get_queue_enable - enable a virtqueue
+ * @ldev: the legacy virtio-pci device
+ * @index: the queue index
+ *
+ * Returns whether a virtqueue is enabled or not
+ */
+bool vp_legacy_get_queue_enable(struct virtio_pci_legacy_device *ldev,
+				u16 index)
+{
+	iowrite16(index, ldev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+	return ioread32(ldev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_get_queue_enable);
+
+/*
+ * vp_legacy_get_queue_size - get size for a virtqueue
+ * @ldev: the legacy virtio-pci device
+ * @index: the queue index
+ *
+ * Returns the size of the virtqueue
+ */
+u16 vp_legacy_get_queue_size(struct virtio_pci_legacy_device *ldev,
+			     u16 index)
+{
+	iowrite16(index, ldev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+	return ioread16(ldev->ioaddr + VIRTIO_PCI_QUEUE_NUM);
+}
+EXPORT_SYMBOL_GPL(vp_legacy_get_queue_size);
+
+MODULE_VERSION("0.1");
+MODULE_DESCRIPTION("Legacy Virtio PCI Device");
+MODULE_AUTHOR("Wu Zongyong <wuzongyong@...ux.alibaba.com>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio_pci_legacy.h b/include/linux/virtio_pci_legacy.h
new file mode 100644
index 000000000000..ee2c6157215f
--- /dev/null
+++ b/include/linux/virtio_pci_legacy.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_VIRTIO_PCI_LEGACY_H
+#define _LINUX_VIRTIO_PCI_LEGACY_H
+
+#include "linux/mod_devicetable.h"
+#include <linux/pci.h>
+#include <linux/virtio_pci.h>
+
+struct virtio_pci_legacy_device {
+	struct pci_dev *pci_dev;
+
+	/* Where to read and clear interrupt */
+	u8 __iomem *isr;
+	/* The IO mapping for the PCI config space (legacy mode only) */
+	void __iomem *ioaddr;
+
+	struct virtio_device_id id;
+};
+
+u64 vp_legacy_get_features(struct virtio_pci_legacy_device *ldev);
+u64 vp_legacy_get_driver_features(struct virtio_pci_legacy_device *ldev);
+void vp_legacy_set_features(struct virtio_pci_legacy_device *ldev,
+			u32 features);
+u8 vp_legacy_get_status(struct virtio_pci_legacy_device *ldev);
+void vp_legacy_set_status(struct virtio_pci_legacy_device *ldev,
+			u8 status);
+u16 vp_legacy_queue_vector(struct virtio_pci_legacy_device *ldev,
+			   u16 idx, u16 vector);
+u16 vp_legacy_config_vector(struct virtio_pci_legacy_device *ldev,
+		     u16 vector);
+void vp_legacy_set_queue_address(struct virtio_pci_legacy_device *ldev,
+			     u16 index, u32 queue_pfn);
+void vp_legacy_set_queue_enable(struct virtio_pci_legacy_device *ldev,
+				u16 idx, bool enable);
+bool vp_legacy_get_queue_enable(struct virtio_pci_legacy_device *ldev,
+				u16 idx);
+void vp_legacy_set_queue_size(struct virtio_pci_legacy_device *ldev,
+			      u16 idx, u16 size);
+u16 vp_legacy_get_queue_size(struct virtio_pci_legacy_device *ldev,
+			     u16 idx);
+int vp_legacy_probe(struct virtio_pci_legacy_device *ldev);
+void vp_legacy_remove(struct virtio_pci_legacy_device *ldev);
+
+#endif
-- 
2.31.1

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