virtio-pci: introduce modern device module

Signed-off-by: Jason Wang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Including a bugfix:

virtio: don't prompt CONFIG_VIRTIO_PCI_MODERN

Cc: Arnd Bergmann <[e-mail]>
Cc: Anders Roxell <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Reported-by: Naresh Kamboju <[e-mail]>
Fixes: 86b87c9d858b6 ("virtio-pci: introduce modern device module")
Signed-off-by: Jason Wang <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Michael S. Tsirkin <[e-mail]>

drivers/virtio/Kconfig

···
 	  This option is selected if the architecture may need to enforce
 	  VIRTIO_F_ACCESS_PLATFORM
 
+config VIRTIO_PCI_LIB
+	tristate
+	help
+	  Modern PCI device implementation. This module implements the
+	  basic probe and control for devices which are based on modern
+	  PCI device with possible vendor specific extensions. Any
+	  module that selects this module must depend on PCI.
+
 menuconfig VIRTIO_MENU
 	bool "Virtio drivers"
 	default y
···
 config VIRTIO_PCI
 	tristate "PCI driver for virtio devices"
 	depends on PCI
+	select VIRTIO_PCI_LIB
 	select VIRTIO
 	help
 	  This driver provides support for virtio based paravirtual device

drivers/virtio/Makefile

···
 # 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-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
 obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
 virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o

drivers/virtio/virtio_pci_common.h

···
 #include <linux/virtio_config.h>
 #include <linux/virtio_ring.h>
 #include <linux/virtio_pci.h>
+#include <linux/virtio_pci_modern.h>
 #include <linux/highmem.h>
 #include <linux/spinlock.h>
 
···
 
 	/* MSI-X vector (or none) */
 	unsigned msix_vector;
-};
-
-struct virtio_pci_modern_device {
-	struct pci_dev *pci_dev;
-
-	struct virtio_pci_common_cfg __iomem *common;
-	/* Device-specific data (non-legacy mode)  */
-	void __iomem *device;
-	/* Base of vq notifications (non-legacy mode). */
-	void __iomem *notify_base;
-	/* Where to read and clear interrupt */
-	u8 __iomem *isr;
-
-	/* So we can sanity-check accesses. */
-	size_t notify_len;
-	size_t device_len;
-
-	/* Capability for when we need to map notifications per-vq. */
-	int notify_map_cap;
-
-	/* Multiply queue_notify_off by this value. (non-legacy mode). */
-	u32 notify_offset_multiplier;
-
-	int modern_bars;
-
-	struct virtio_device_id id;
 };
 
 /* Our device structure */

drivers/virtio/virtio_pci_modern.c

···
 #define VIRTIO_RING_NO_LEGACY
 #include "virtio_pci_common.h"
 
-/*
- * Type-safe wrappers for io accesses.
- * Use these to enforce at compile time the following spec requirement:
- *
- * The driver MUST access each field using the “natural” access
- * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses
- * for 16-bit fields and 8-bit accesses for 8-bit fields.
- */
-static inline u8 vp_ioread8(const u8 __iomem *addr)
-{
-	return ioread8(addr);
-}
-static inline u16 vp_ioread16 (const __le16 __iomem *addr)
-{
-	return ioread16(addr);
-}
-
-static inline u32 vp_ioread32(const __le32 __iomem *addr)
-{
-	return ioread32(addr);
-}
-
-static inline void vp_iowrite8(u8 value, u8 __iomem *addr)
-{
-	iowrite8(value, addr);
-}
-
-static inline void vp_iowrite16(u16 value, __le16 __iomem *addr)
-{
-	iowrite16(value, addr);
-}
-
-static inline void vp_iowrite32(u32 value, __le32 __iomem *addr)
-{
-	iowrite32(value, addr);
-}
-
-static void vp_iowrite64_twopart(u64 val,
-				 __le32 __iomem *lo, __le32 __iomem *hi)
-{
-	vp_iowrite32((u32)val, lo);
-	vp_iowrite32(val >> 32, hi);
-}
-
-/*
- * vp_modern_map_capability - map a part of virtio pci capability
- * @mdev: the modern virtio-pci device
- * @off: offset of the capability
- * @minlen: minimal length of the capability
- * @align: align requirement
- * @start: start from the capability
- * @size: map size
- * @len: the length that is actually mapped
- *
- * Returns the io address of for the part of the capability
- */
-void __iomem *vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
-				       size_t minlen,
-				       u32 align,
-				       u32 start, u32 size,
-				       size_t *len)
-{
-	struct pci_dev *dev = mdev->pci_dev;
-	u8 bar;
-	u32 offset, length;
-	void __iomem *p;
-
-	pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap,
-						 bar),
-			     &bar);
-	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
-			     &offset);
-	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
-			      &length);
-
-	if (length <= start) {
-		dev_err(&dev->dev,
-			"virtio_pci: bad capability len %u (>%u expected)\n",
-			length, start);
-		return NULL;
-	}
-
-	if (length - start < minlen) {
-		dev_err(&dev->dev,
-			"virtio_pci: bad capability len %u (>=%zu expected)\n",
-			length, minlen);
-		return NULL;
-	}
-
-	length -= start;
-
-	if (start + offset < offset) {
-		dev_err(&dev->dev,
-			"virtio_pci: map wrap-around %u+%u\n",
-			start, offset);
-		return NULL;
-	}
-
-	offset += start;
-
-	if (offset & (align - 1)) {
-		dev_err(&dev->dev,
-			"virtio_pci: offset %u not aligned to %u\n",
-			offset, align);
-		return NULL;
-	}
-
-	if (length > size)
-		length = size;
-
-	if (len)
-		*len = length;
-
-	if (minlen + offset < minlen ||
-	    minlen + offset > pci_resource_len(dev, bar)) {
-		dev_err(&dev->dev,
-			"virtio_pci: map virtio %zu@%u "
-			"out of range on bar %i length %lu\n",
-			minlen, offset,
-			bar, (unsigned long)pci_resource_len(dev, bar));
-		return NULL;
-	}
-
-	p = pci_iomap_range(dev, bar, offset, length);
-	if (!p)
-		dev_err(&dev->dev,
-			"virtio_pci: unable to map virtio %u@%u on bar %i\n",
-			length, offset, bar);
-	return p;
-}
-
-/*
- * vp_modern_get_features - get features from device
- * @mdev: the modern virtio-pci device
- *
- * Returns the features read from the device
- */
-static u64 vp_modern_get_features(struct virtio_pci_modern_device *mdev)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	u64 features;
-
-	vp_iowrite32(0, &cfg->device_feature_select);
-	features = vp_ioread32(&cfg->device_feature);
-	vp_iowrite32(1, &cfg->device_feature_select);
-	features |= ((u64)vp_ioread32(&cfg->device_feature) << 32);
-
-	return features;
-}
-
-/* virtio config->get_features() implementation */
 static u64 vp_get_features(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
···
 	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
 			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
 		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
-}
-
-/*
- * vp_modern_set_features - set features to device
- * @mdev: the modern virtio-pci device
- * @features: the features set to device
- */
-static void vp_modern_set_features(struct virtio_pci_modern_device *mdev,
-				   u64 features)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	vp_iowrite32(0, &cfg->guest_feature_select);
-	vp_iowrite32((u32)features, &cfg->guest_feature);
-	vp_iowrite32(1, &cfg->guest_feature_select);
-	vp_iowrite32(features >> 32, &cfg->guest_feature);
-}
-
-/*
- * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
- * @mdev: the modern virtio-pci device
- * @index: queue index
- * @vector: the config vector
- *
- * Returns the config vector read from the device
- */
-static u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
-				  u16 index, u16 vector)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	vp_iowrite16(index, &cfg->queue_select);
-	vp_iowrite16(vector, &cfg->queue_msix_vector);
-	/* Flush the write out to device */
-	return vp_ioread16(&cfg->queue_msix_vector);
-}
-
-/*
- * vp_modern_queue_address - set the virtqueue address
- * @mdev: the modern virtio-pci device
- * @index: the queue index
- * @desc_addr: address of the descriptor area
- * @driver_addr: address of the driver area
- * @device_addr: address of the device area
- */
-static void vp_modern_queue_address(struct virtio_pci_modern_device *mdev,
-				    u16 index, u64 desc_addr, u64 driver_addr,
-				    u64 device_addr)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	vp_iowrite16(index, &cfg->queue_select);
-
-	vp_iowrite64_twopart(desc_addr, &cfg->queue_desc_lo,
-			     &cfg->queue_desc_hi);
-	vp_iowrite64_twopart(driver_addr, &cfg->queue_avail_lo,
-			     &cfg->queue_avail_hi);
-	vp_iowrite64_twopart(device_addr, &cfg->queue_used_lo,
-			     &cfg->queue_used_hi);
-}
-
-/*
- * vp_modern_set_queue_enable - enable a virtqueue
- * @mdev: the modern virtio-pci device
- * @index: the queue index
- * @enable: whether the virtqueue is enable or not
- */
-static void vp_modern_set_queue_enable(struct virtio_pci_modern_device *mdev,
-				       u16 index, bool enable)
-{
-	vp_iowrite16(index, &mdev->common->queue_select);
-	vp_iowrite16(enable, &mdev->common->queue_enable);
-}
-
-/*
- * vp_modern_get_queue_enable - enable a virtqueue
- * @mdev: the modern virtio-pci device
- * @index: the queue index
- *
- * Returns whether a virtqueue is enabled or not
- */
-static bool vp_modern_get_queue_enable(struct virtio_pci_modern_device *mdev,
-				       u16 index)
-{
-	vp_iowrite16(index, &mdev->common->queue_select);
-
-	return vp_ioread16(&mdev->common->queue_enable);
-}
-
-/*
- * vp_modern_set_queue_size - set size for a virtqueue
- * @mdev: the modern virtio-pci device
- * @index: the queue index
- * @size: the size of the virtqueue
- */
-static void vp_modern_set_queue_size(struct virtio_pci_modern_device *mdev,
-				     u16 index, u16 size)
-{
-	vp_iowrite16(index, &mdev->common->queue_select);
-	vp_iowrite16(size, &mdev->common->queue_size);
-
-}
-
-/*
- * vp_modern_get_queue_size - get size for a virtqueue
- * @mdev: the modern virtio-pci device
- * @index: the queue index
- *
- * Returns the size of the virtqueue
- */
-static u16 vp_modern_get_queue_size(struct virtio_pci_modern_device *mdev,
-				    u16 index)
-{
-	vp_iowrite16(index, &mdev->common->queue_select);
-
-	return vp_ioread16(&mdev->common->queue_size);
-
-}
-
-/*
- * vp_modern_get_num_queues - get the number of virtqueues
- * @mdev: the modern virtio-pci device
- *
- * Returns the number of virtqueues
- */
-static u16 vp_modern_get_num_queues(struct virtio_pci_modern_device *mdev)
-{
-	return vp_ioread16(&mdev->common->num_queues);
-}
-
-/*
- * vp_modern_get_queue_notify_off - get notification offset for a virtqueue
- * @mdev: the modern virtio-pci device
- * @index: the queue index
- *
- * Returns the notification offset for a virtqueue
- */
-static u16 vp_modern_get_queue_notify_off(struct virtio_pci_modern_device *mdev,
-					  u16 index)
-{
-	vp_iowrite16(index, &mdev->common->queue_select);
-
-	return vp_ioread16(&mdev->common->queue_notify_off);
 }
 
 /* virtio config->finalize_features() implementation */
···
 	}
 }
 
-/*
- * vp_modern_generation - get the device genreation
- * @mdev: the modern virtio-pci device
- *
- * Returns the genreation read from device
- */
-static u32 vp_modern_generation(struct virtio_pci_modern_device *mdev)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	return vp_ioread8(&cfg->config_generation);
-}
-
 static u32 vp_generation(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 
 	return vp_modern_generation(&vp_dev->mdev);
-}
-
-/*
- * vp_modern_get_status - get the device status
- * @mdev: the modern virtio-pci device
- *
- * Returns the status read from device
- */
-static u8 vp_modern_get_status(struct virtio_pci_modern_device *mdev)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	return vp_ioread8(&cfg->device_status);
 }
 
 /* config->{get,set}_status() implementations */
···
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 
 	return vp_modern_get_status(&vp_dev->mdev);
-}
-
-/*
- * vp_modern_set_status - set status to device
- * @mdev: the modern virtio-pci device
- * @status: the status set to device
- */
-static void vp_modern_set_status(struct virtio_pci_modern_device *mdev,
-				 u8 status)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	vp_iowrite8(status, &cfg->device_status);
 }
 
 static void vp_set_status(struct virtio_device *vdev, u8 status)
···
 		msleep(1);
 	/* Flush pending VQ/configuration callbacks. */
 	vp_synchronize_vectors(vdev);
-}
-
-/*
- * vp_modern_config_vector - set the vector for config interrupt
- * @mdev: the modern virtio-pci device
- * @vector: the config vector
- *
- * Returns the config vector read from the device
- */
-static u16 vp_modern_config_vector(struct virtio_pci_modern_device *mdev,
-				   u16 vector)
-{
-	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
-
-	/* Setup the vector used for configuration events */
-	vp_iowrite16(vector, &cfg->msix_config);
-	/* Verify we had enough resources to assign the vector */
-	/* Will also flush the write out to device */
-	return vp_ioread16(&cfg->msix_config);
 }
 
 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
···
 	.get_shm_region  = vp_get_shm_region,
 };
 
-/**
- * virtio_pci_find_capability - walk capabilities to find device info.
- * @dev: the pci device
- * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
- * @ioresource_types: IORESOURCE_MEM and/or IORESOURCE_IO.
- * @bars: the bitmask of BARs
- *
- * Returns offset of the capability, or 0.
- */
-static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
-					     u32 ioresource_types, int *bars)
-{
-	int pos;
-
-	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
-	     pos > 0;
-	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
-		u8 type, bar;
-		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
-							 cfg_type),
-				     &type);
-		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
-							 bar),
-				     &bar);
-
-		/* Ignore structures with reserved BAR values */
-		if (bar > 0x5)
-			continue;
-
-		if (type == cfg_type) {
-			if (pci_resource_len(dev, bar) &&
-			    pci_resource_flags(dev, bar) & ioresource_types) {
-				*bars |= (1 << bar);
-				return pos;
-			}
-		}
-	}
-	return 0;
-}
-
-/* This is part of the ABI.  Don't screw with it. */
-static inline void check_offsets(void)
-{
-	/* Note: disk space was harmed in compilation of this function. */
-	BUILD_BUG_ON(VIRTIO_PCI_CAP_VNDR !=
-		     offsetof(struct virtio_pci_cap, cap_vndr));
-	BUILD_BUG_ON(VIRTIO_PCI_CAP_NEXT !=
-		     offsetof(struct virtio_pci_cap, cap_next));
-	BUILD_BUG_ON(VIRTIO_PCI_CAP_LEN !=
-		     offsetof(struct virtio_pci_cap, cap_len));
-	BUILD_BUG_ON(VIRTIO_PCI_CAP_CFG_TYPE !=
-		     offsetof(struct virtio_pci_cap, cfg_type));
-	BUILD_BUG_ON(VIRTIO_PCI_CAP_BAR !=
-		     offsetof(struct virtio_pci_cap, bar));
-	BUILD_BUG_ON(VIRTIO_PCI_CAP_OFFSET !=
-		     offsetof(struct virtio_pci_cap, offset));
-	BUILD_BUG_ON(VIRTIO_PCI_CAP_LENGTH !=
-		     offsetof(struct virtio_pci_cap, length));
-	BUILD_BUG_ON(VIRTIO_PCI_NOTIFY_CAP_MULT !=
-		     offsetof(struct virtio_pci_notify_cap,
-			      notify_off_multiplier));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DFSELECT !=
-		     offsetof(struct virtio_pci_common_cfg,
-			      device_feature_select));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DF !=
-		     offsetof(struct virtio_pci_common_cfg, device_feature));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GFSELECT !=
-		     offsetof(struct virtio_pci_common_cfg,
-			      guest_feature_select));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GF !=
-		     offsetof(struct virtio_pci_common_cfg, guest_feature));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_MSIX !=
-		     offsetof(struct virtio_pci_common_cfg, msix_config));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_NUMQ !=
-		     offsetof(struct virtio_pci_common_cfg, num_queues));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_STATUS !=
-		     offsetof(struct virtio_pci_common_cfg, device_status));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_CFGGENERATION !=
-		     offsetof(struct virtio_pci_common_cfg, config_generation));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SELECT !=
-		     offsetof(struct virtio_pci_common_cfg, queue_select));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SIZE !=
-		     offsetof(struct virtio_pci_common_cfg, queue_size));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_MSIX !=
-		     offsetof(struct virtio_pci_common_cfg, queue_msix_vector));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_ENABLE !=
-		     offsetof(struct virtio_pci_common_cfg, queue_enable));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NOFF !=
-		     offsetof(struct virtio_pci_common_cfg, queue_notify_off));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCLO !=
-		     offsetof(struct virtio_pci_common_cfg, queue_desc_lo));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCHI !=
-		     offsetof(struct virtio_pci_common_cfg, queue_desc_hi));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILLO !=
-		     offsetof(struct virtio_pci_common_cfg, queue_avail_lo));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILHI !=
-		     offsetof(struct virtio_pci_common_cfg, queue_avail_hi));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDLO !=
-		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
-	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI !=
-		     offsetof(struct virtio_pci_common_cfg, queue_used_hi));
-}
-
-/*
- * vp_modern_probe: probe the modern virtio pci device, note that the
- * caller is required to enable PCI device before calling this function.
- * @mdev: the modern virtio-pci device
- *
- * Return 0 on succeed otherwise fail
- */
-static int vp_modern_probe(struct virtio_pci_modern_device *mdev)
-{
-	struct pci_dev *pci_dev = mdev->pci_dev;
-	int err, common, isr, notify, device;
-	u32 notify_length;
-	u32 notify_offset;
-
-	check_offsets();
-
-	mdev->pci_dev = pci_dev;
-
-	/* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */
-	if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f)
-		return -ENODEV;
-
-	if (pci_dev->device < 0x1040) {
-		/* Transitional devices: use the PCI subsystem device id as
-		 * virtio device id, same as legacy driver always did.
-		 */
-		mdev->id.device = pci_dev->subsystem_device;
-	} else {
-		/* Modern devices: simply use PCI device id, but start from 0x1040. */
-		mdev->id.device = pci_dev->device - 0x1040;
-	}
-	mdev->id.vendor = pci_dev->subsystem_vendor;
-
-	/* check for a common config: if not, use legacy mode (bar 0). */
-	common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG,
-					    IORESOURCE_IO | IORESOURCE_MEM,
-					    &mdev->modern_bars);
-	if (!common) {
-		dev_info(&pci_dev->dev,
-			 "virtio_pci: leaving for legacy driver\n");
-		return -ENODEV;
-	}
-
-	/* If common is there, these should be too... */
-	isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG,
-					 IORESOURCE_IO | IORESOURCE_MEM,
-					 &mdev->modern_bars);
-	notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG,
-					    IORESOURCE_IO | IORESOURCE_MEM,
-					    &mdev->modern_bars);
-	if (!isr || !notify) {
-		dev_err(&pci_dev->dev,
-			"virtio_pci: missing capabilities %i/%i/%i\n",
-			common, isr, notify);
-		return -EINVAL;
-	}
-
-	err = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(64));
-	if (err)
-		err = dma_set_mask_and_coherent(&pci_dev->dev,
-						DMA_BIT_MASK(32));
-	if (err)
-		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
-
-	/* Device capability is only mandatory for devices that have
-	 * device-specific configuration.
-	 */
-	device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG,
-					    IORESOURCE_IO | IORESOURCE_MEM,
-					    &mdev->modern_bars);
-
-	err = pci_request_selected_regions(pci_dev, mdev->modern_bars,
-					   "virtio-pci-modern");
-	if (err)
-		return err;
-
-	err = -EINVAL;
-	mdev->common = vp_modern_map_capability(mdev, common,
-				      sizeof(struct virtio_pci_common_cfg), 4,
-				      0, sizeof(struct virtio_pci_common_cfg),
-				      NULL);
-	if (!mdev->common)
-		goto err_map_common;
-	mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
-					     0, 1,
-					     NULL);
-	if (!mdev->isr)
-		goto err_map_isr;
-
-	/* Read notify_off_multiplier from config space. */
-	pci_read_config_dword(pci_dev,
-			      notify + offsetof(struct virtio_pci_notify_cap,
-						notify_off_multiplier),
-			      &mdev->notify_offset_multiplier);
-	/* Read notify length and offset from config space. */
-	pci_read_config_dword(pci_dev,
-			      notify + offsetof(struct virtio_pci_notify_cap,
-						cap.length),
-			      &notify_length);
-
-	pci_read_config_dword(pci_dev,
-			      notify + offsetof(struct virtio_pci_notify_cap,
-						cap.offset),
-			      &notify_offset);
-
-	/* We don't know how many VQs we'll map, ahead of the time.
-	 * If notify length is small, map it all now.
-	 * Otherwise, map each VQ individually later.
-	 */
-	if ((u64)notify_length + (notify_offset % PAGE_SIZE) <= PAGE_SIZE) {
-		mdev->notify_base = vp_modern_map_capability(mdev, notify,
-							     2, 2,
-							     0, notify_length,
-							     &mdev->notify_len);
-		if (!mdev->notify_base)
-			goto err_map_notify;
-	} else {
-		mdev->notify_map_cap = notify;
-	}
-
-	/* Again, we don't know how much we should map, but PAGE_SIZE
-	 * is more than enough for all existing devices.
-	 */
-	if (device) {
-		mdev->device = vp_modern_map_capability(mdev, device, 0, 4,
-							0, PAGE_SIZE,
-							&mdev->device_len);
-		if (!mdev->device)
-			goto err_map_device;
-	}
-
-	return 0;
-
-err_map_device:
-	if (mdev->notify_base)
-		pci_iounmap(pci_dev, mdev->notify_base);
-err_map_notify:
-	pci_iounmap(pci_dev, mdev->isr);
-err_map_isr:
-	pci_iounmap(pci_dev, mdev->common);
-err_map_common:
-	return err;
-}
-
 /* the PCI probing function */
 int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev)
 {
···
 	vp_dev->vdev.id = mdev->id;
 
 	return 0;
-}
-
-/*
- * vp_modern_probe: remove and cleanup the modern virtio pci device
- * @mdev: the modern virtio-pci device
- */
-static void vp_modern_remove(struct virtio_pci_modern_device *mdev)
-{
-	struct pci_dev *pci_dev = mdev->pci_dev;
-
-	if (mdev->device)
-		pci_iounmap(pci_dev, mdev->device);
-	if (mdev->notify_base)
-		pci_iounmap(pci_dev, mdev->notify_base);
-	pci_iounmap(pci_dev, mdev->isr);
-	pci_iounmap(pci_dev, mdev->common);
-	pci_release_selected_regions(pci_dev, mdev->modern_bars);
 }
 
 void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev)

drivers/virtio/virtio_pci_modern_dev.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/virtio_pci_modern.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+
+/*
+ * vp_modern_map_capability - map a part of virtio pci capability
+ * @mdev: the modern virtio-pci device
+ * @off: offset of the capability
+ * @minlen: minimal length of the capability
+ * @align: align requirement
+ * @start: start from the capability
+ * @size: map size
+ * @len: the length that is actually mapped
+ *
+ * Returns the io address of for the part of the capability
+ */
+void __iomem *vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
+				       size_t minlen,
+				       u32 align,
+				       u32 start, u32 size,
+				       size_t *len)
+{
+	struct pci_dev *dev = mdev->pci_dev;
+	u8 bar;
+	u32 offset, length;
+	void __iomem *p;
+
+	pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap,
+						 bar),
+			     &bar);
+	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
+			     &offset);
+	pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
+			      &length);
+
+	if (length <= start) {
+		dev_err(&dev->dev,
+			"virtio_pci: bad capability len %u (>%u expected)\n",
+			length, start);
+		return NULL;
+	}
+
+	if (length - start < minlen) {
+		dev_err(&dev->dev,
+			"virtio_pci: bad capability len %u (>=%zu expected)\n",
+			length, minlen);
+		return NULL;
+	}
+
+	length -= start;
+
+	if (start + offset < offset) {
+		dev_err(&dev->dev,
+			"virtio_pci: map wrap-around %u+%u\n",
+			start, offset);
+		return NULL;
+	}
+
+	offset += start;
+
+	if (offset & (align - 1)) {
+		dev_err(&dev->dev,
+			"virtio_pci: offset %u not aligned to %u\n",
+			offset, align);
+		return NULL;
+	}
+
+	if (length > size)
+		length = size;
+
+	if (len)
+		*len = length;
+
+	if (minlen + offset < minlen ||
+	    minlen + offset > pci_resource_len(dev, bar)) {
+		dev_err(&dev->dev,
+			"virtio_pci: map virtio %zu@%u "
+			"out of range on bar %i length %lu\n",
+			minlen, offset,
+			bar, (unsigned long)pci_resource_len(dev, bar));
+		return NULL;
+	}
+
+	p = pci_iomap_range(dev, bar, offset, length);
+	if (!p)
+		dev_err(&dev->dev,
+			"virtio_pci: unable to map virtio %u@%u on bar %i\n",
+			length, offset, bar);
+	return p;
+}
+EXPORT_SYMBOL_GPL(vp_modern_map_capability);
+
+/**
+ * virtio_pci_find_capability - walk capabilities to find device info.
+ * @dev: the pci device
+ * @cfg_type: the VIRTIO_PCI_CAP_* value we seek
+ * @ioresource_types: IORESOURCE_MEM and/or IORESOURCE_IO.
+ * @bars: the bitmask of BARs
+ *
+ * Returns offset of the capability, or 0.
+ */
+static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
+					     u32 ioresource_types, int *bars)
+{
+	int pos;
+
+	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
+	     pos > 0;
+	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
+		u8 type, bar;
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 cfg_type),
+				     &type);
+		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
+							 bar),
+				     &bar);
+
+		/* Ignore structures with reserved BAR values */
+		if (bar > 0x5)
+			continue;
+
+		if (type == cfg_type) {
+			if (pci_resource_len(dev, bar) &&
+			    pci_resource_flags(dev, bar) & ioresource_types) {
+				*bars |= (1 << bar);
+				return pos;
+			}
+		}
+	}
+	return 0;
+}
+
+/* This is part of the ABI.  Don't screw with it. */
+static inline void check_offsets(void)
+{
+	/* Note: disk space was harmed in compilation of this function. */
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_VNDR !=
+		     offsetof(struct virtio_pci_cap, cap_vndr));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_NEXT !=
+		     offsetof(struct virtio_pci_cap, cap_next));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_LEN !=
+		     offsetof(struct virtio_pci_cap, cap_len));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_CFG_TYPE !=
+		     offsetof(struct virtio_pci_cap, cfg_type));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_BAR !=
+		     offsetof(struct virtio_pci_cap, bar));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_OFFSET !=
+		     offsetof(struct virtio_pci_cap, offset));
+	BUILD_BUG_ON(VIRTIO_PCI_CAP_LENGTH !=
+		     offsetof(struct virtio_pci_cap, length));
+	BUILD_BUG_ON(VIRTIO_PCI_NOTIFY_CAP_MULT !=
+		     offsetof(struct virtio_pci_notify_cap,
+			      notify_off_multiplier));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DFSELECT !=
+		     offsetof(struct virtio_pci_common_cfg,
+			      device_feature_select));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_DF !=
+		     offsetof(struct virtio_pci_common_cfg, device_feature));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GFSELECT !=
+		     offsetof(struct virtio_pci_common_cfg,
+			      guest_feature_select));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_GF !=
+		     offsetof(struct virtio_pci_common_cfg, guest_feature));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_MSIX !=
+		     offsetof(struct virtio_pci_common_cfg, msix_config));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_NUMQ !=
+		     offsetof(struct virtio_pci_common_cfg, num_queues));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_STATUS !=
+		     offsetof(struct virtio_pci_common_cfg, device_status));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_CFGGENERATION !=
+		     offsetof(struct virtio_pci_common_cfg, config_generation));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SELECT !=
+		     offsetof(struct virtio_pci_common_cfg, queue_select));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SIZE !=
+		     offsetof(struct virtio_pci_common_cfg, queue_size));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_MSIX !=
+		     offsetof(struct virtio_pci_common_cfg, queue_msix_vector));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_ENABLE !=
+		     offsetof(struct virtio_pci_common_cfg, queue_enable));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NOFF !=
+		     offsetof(struct virtio_pci_common_cfg, queue_notify_off));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCLO !=
+		     offsetof(struct virtio_pci_common_cfg, queue_desc_lo));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCHI !=
+		     offsetof(struct virtio_pci_common_cfg, queue_desc_hi));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILLO !=
+		     offsetof(struct virtio_pci_common_cfg, queue_avail_lo));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILHI !=
+		     offsetof(struct virtio_pci_common_cfg, queue_avail_hi));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDLO !=
+		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI !=
+		     offsetof(struct virtio_pci_common_cfg, queue_used_hi));
+}
+
+/*
+ * vp_modern_probe: probe the modern virtio pci device, note that the
+ * caller is required to enable PCI device before calling this function.
+ * @mdev: the modern virtio-pci device
+ *
+ * Return 0 on succeed otherwise fail
+ */
+int vp_modern_probe(struct virtio_pci_modern_device *mdev)
+{
+	struct pci_dev *pci_dev = mdev->pci_dev;
+	int err, common, isr, notify, device;
+	u32 notify_length;
+	u32 notify_offset;
+
+	check_offsets();
+
+	mdev->pci_dev = pci_dev;
+
+	/* We only own devices >= 0x1000 and <= 0x107f: leave the rest. */
+	if (pci_dev->device < 0x1000 || pci_dev->device > 0x107f)
+		return -ENODEV;
+
+	if (pci_dev->device < 0x1040) {
+		/* Transitional devices: use the PCI subsystem device id as
+		 * virtio device id, same as legacy driver always did.
+		 */
+		mdev->id.device = pci_dev->subsystem_device;
+	} else {
+		/* Modern devices: simply use PCI device id, but start from 0x1040. */
+		mdev->id.device = pci_dev->device - 0x1040;
+	}
+	mdev->id.vendor = pci_dev->subsystem_vendor;
+
+	/* check for a common config: if not, use legacy mode (bar 0). */
+	common = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_COMMON_CFG,
+					    IORESOURCE_IO | IORESOURCE_MEM,
+					    &mdev->modern_bars);
+	if (!common) {
+		dev_info(&pci_dev->dev,
+			 "virtio_pci: leaving for legacy driver\n");
+		return -ENODEV;
+	}
+
+	/* If common is there, these should be too... */
+	isr = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_ISR_CFG,
+					 IORESOURCE_IO | IORESOURCE_MEM,
+					 &mdev->modern_bars);
+	notify = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_NOTIFY_CFG,
+					    IORESOURCE_IO | IORESOURCE_MEM,
+					    &mdev->modern_bars);
+	if (!isr || !notify) {
+		dev_err(&pci_dev->dev,
+			"virtio_pci: missing capabilities %i/%i/%i\n",
+			common, isr, notify);
+		return -EINVAL;
+	}
+
+	err = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(64));
+	if (err)
+		err = dma_set_mask_and_coherent(&pci_dev->dev,
+						DMA_BIT_MASK(32));
+	if (err)
+		dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");
+
+	/* Device capability is only mandatory for devices that have
+	 * device-specific configuration.
+	 */
+	device = virtio_pci_find_capability(pci_dev, VIRTIO_PCI_CAP_DEVICE_CFG,
+					    IORESOURCE_IO | IORESOURCE_MEM,
+					    &mdev->modern_bars);
+
+	err = pci_request_selected_regions(pci_dev, mdev->modern_bars,
+					   "virtio-pci-modern");
+	if (err)
+		return err;
+
+	err = -EINVAL;
+	mdev->common = vp_modern_map_capability(mdev, common,
+				      sizeof(struct virtio_pci_common_cfg), 4,
+				      0, sizeof(struct virtio_pci_common_cfg),
+				      NULL);
+	if (!mdev->common)
+		goto err_map_common;
+	mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
+					     0, 1,
+					     NULL);
+	if (!mdev->isr)
+		goto err_map_isr;
+
+	/* Read notify_off_multiplier from config space. */
+	pci_read_config_dword(pci_dev,
+			      notify + offsetof(struct virtio_pci_notify_cap,
+						notify_off_multiplier),
+			      &mdev->notify_offset_multiplier);
+	/* Read notify length and offset from config space. */
+	pci_read_config_dword(pci_dev,
+			      notify + offsetof(struct virtio_pci_notify_cap,
+						cap.length),
+			      &notify_length);
+
+	pci_read_config_dword(pci_dev,
+			      notify + offsetof(struct virtio_pci_notify_cap,
+						cap.offset),
+			      &notify_offset);
+
+	/* We don't know how many VQs we'll map, ahead of the time.
+	 * If notify length is small, map it all now.
+	 * Otherwise, map each VQ individually later.
+	 */
+	if ((u64)notify_length + (notify_offset % PAGE_SIZE) <= PAGE_SIZE) {
+		mdev->notify_base = vp_modern_map_capability(mdev, notify,
+							     2, 2,
+							     0, notify_length,
+							     &mdev->notify_len);
+		if (!mdev->notify_base)
+			goto err_map_notify;
+	} else {
+		mdev->notify_map_cap = notify;
+	}
+
+	/* Again, we don't know how much we should map, but PAGE_SIZE
+	 * is more than enough for all existing devices.
+	 */
+	if (device) {
+		mdev->device = vp_modern_map_capability(mdev, device, 0, 4,
+							0, PAGE_SIZE,
+							&mdev->device_len);
+		if (!mdev->device)
+			goto err_map_device;
+	}
+
+	return 0;
+
+err_map_device:
+	if (mdev->notify_base)
+		pci_iounmap(pci_dev, mdev->notify_base);
+err_map_notify:
+	pci_iounmap(pci_dev, mdev->isr);
+err_map_isr:
+	pci_iounmap(pci_dev, mdev->common);
+err_map_common:
+	return err;
+}
+EXPORT_SYMBOL_GPL(vp_modern_probe);
+
+/*
+ * vp_modern_probe: remove and cleanup the modern virtio pci device
+ * @mdev: the modern virtio-pci device
+ */
+void vp_modern_remove(struct virtio_pci_modern_device *mdev)
+{
+	struct pci_dev *pci_dev = mdev->pci_dev;
+
+	if (mdev->device)
+		pci_iounmap(pci_dev, mdev->device);
+	if (mdev->notify_base)
+		pci_iounmap(pci_dev, mdev->notify_base);
+	pci_iounmap(pci_dev, mdev->isr);
+	pci_iounmap(pci_dev, mdev->common);
+	pci_release_selected_regions(pci_dev, mdev->modern_bars);
+}
+EXPORT_SYMBOL_GPL(vp_modern_remove);
+
+/*
+ * vp_modern_get_features - get features from device
+ * @mdev: the modern virtio-pci device
+ *
+ * Returns the features read from the device
+ */
+u64 vp_modern_get_features(struct virtio_pci_modern_device *mdev)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	u64 features;
+
+	vp_iowrite32(0, &cfg->device_feature_select);
+	features = vp_ioread32(&cfg->device_feature);
+	vp_iowrite32(1, &cfg->device_feature_select);
+	features |= ((u64)vp_ioread32(&cfg->device_feature) << 32);
+
+	return features;
+}
+EXPORT_SYMBOL_GPL(vp_modern_get_features);
+
+/*
+ * vp_modern_set_features - set features to device
+ * @mdev: the modern virtio-pci device
+ * @features: the features set to device
+ */
+void vp_modern_set_features(struct virtio_pci_modern_device *mdev,
+			    u64 features)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	vp_iowrite32(0, &cfg->guest_feature_select);
+	vp_iowrite32((u32)features, &cfg->guest_feature);
+	vp_iowrite32(1, &cfg->guest_feature_select);
+	vp_iowrite32(features >> 32, &cfg->guest_feature);
+}
+EXPORT_SYMBOL_GPL(vp_modern_set_features);
+
+/*
+ * vp_modern_generation - get the device genreation
+ * @mdev: the modern virtio-pci device
+ *
+ * Returns the genreation read from device
+ */
+u32 vp_modern_generation(struct virtio_pci_modern_device *mdev)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	return vp_ioread8(&cfg->config_generation);
+}
+EXPORT_SYMBOL_GPL(vp_modern_generation);
+
+/*
+ * vp_modern_get_status - get the device status
+ * @mdev: the modern virtio-pci device
+ *
+ * Returns the status read from device
+ */
+u8 vp_modern_get_status(struct virtio_pci_modern_device *mdev)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	return vp_ioread8(&cfg->device_status);
+}
+EXPORT_SYMBOL_GPL(vp_modern_get_status);
+
+/*
+ * vp_modern_set_status - set status to device
+ * @mdev: the modern virtio-pci device
+ * @status: the status set to device
+ */
+void vp_modern_set_status(struct virtio_pci_modern_device *mdev,
+				 u8 status)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	vp_iowrite8(status, &cfg->device_status);
+}
+EXPORT_SYMBOL_GPL(vp_modern_set_status);
+
+/*
+ * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: queue index
+ * @vector: the config vector
+ *
+ * Returns the config vector read from the device
+ */
+u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
+			   u16 index, u16 vector)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	vp_iowrite16(index, &cfg->queue_select);
+	vp_iowrite16(vector, &cfg->queue_msix_vector);
+	/* Flush the write out to device */
+	return vp_ioread16(&cfg->queue_msix_vector);
+}
+EXPORT_SYMBOL_GPL(vp_modern_queue_vector);
+
+/*
+ * vp_modern_config_vector - set the vector for config interrupt
+ * @mdev: the modern virtio-pci device
+ * @vector: the config vector
+ *
+ * Returns the config vector read from the device
+ */
+u16 vp_modern_config_vector(struct virtio_pci_modern_device *mdev,
+			    u16 vector)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	/* Setup the vector used for configuration events */
+	vp_iowrite16(vector, &cfg->msix_config);
+	/* Verify we had enough resources to assign the vector */
+	/* Will also flush the write out to device */
+	return vp_ioread16(&cfg->msix_config);
+}
+EXPORT_SYMBOL_GPL(vp_modern_config_vector);
+
+/*
+ * vp_modern_queue_address - set the virtqueue address
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ * @desc_addr: address of the descriptor area
+ * @driver_addr: address of the driver area
+ * @device_addr: address of the device area
+ */
+void vp_modern_queue_address(struct virtio_pci_modern_device *mdev,
+			     u16 index, u64 desc_addr, u64 driver_addr,
+			     u64 device_addr)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	vp_iowrite16(index, &cfg->queue_select);
+
+	vp_iowrite64_twopart(desc_addr, &cfg->queue_desc_lo,
+			     &cfg->queue_desc_hi);
+	vp_iowrite64_twopart(driver_addr, &cfg->queue_avail_lo,
+			     &cfg->queue_avail_hi);
+	vp_iowrite64_twopart(device_addr, &cfg->queue_used_lo,
+			     &cfg->queue_used_hi);
+}
+EXPORT_SYMBOL_GPL(vp_modern_queue_address);
+
+/*
+ * vp_modern_set_queue_enable - enable a virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ * @enable: whether the virtqueue is enable or not
+ */
+void vp_modern_set_queue_enable(struct virtio_pci_modern_device *mdev,
+				u16 index, bool enable)
+{
+	vp_iowrite16(index, &mdev->common->queue_select);
+	vp_iowrite16(enable, &mdev->common->queue_enable);
+}
+EXPORT_SYMBOL_GPL(vp_modern_set_queue_enable);
+
+/*
+ * vp_modern_get_queue_enable - enable a virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ *
+ * Returns whether a virtqueue is enabled or not
+ */
+bool vp_modern_get_queue_enable(struct virtio_pci_modern_device *mdev,
+				u16 index)
+{
+	vp_iowrite16(index, &mdev->common->queue_select);
+
+	return vp_ioread16(&mdev->common->queue_enable);
+}
+EXPORT_SYMBOL_GPL(vp_modern_get_queue_enable);
+
+/*
+ * vp_modern_set_queue_size - set size for a virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ * @size: the size of the virtqueue
+ */
+void vp_modern_set_queue_size(struct virtio_pci_modern_device *mdev,
+			      u16 index, u16 size)
+{
+	vp_iowrite16(index, &mdev->common->queue_select);
+	vp_iowrite16(size, &mdev->common->queue_size);
+
+}
+EXPORT_SYMBOL_GPL(vp_modern_set_queue_size);
+
+/*
+ * vp_modern_get_queue_size - get size for a virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ *
+ * Returns the size of the virtqueue
+ */
+u16 vp_modern_get_queue_size(struct virtio_pci_modern_device *mdev,
+			     u16 index)
+{
+	vp_iowrite16(index, &mdev->common->queue_select);
+
+	return vp_ioread16(&mdev->common->queue_size);
+
+}
+EXPORT_SYMBOL_GPL(vp_modern_get_queue_size);
+
+/*
+ * vp_modern_get_num_queues - get the number of virtqueues
+ * @mdev: the modern virtio-pci device
+ *
+ * Returns the number of virtqueues
+ */
+u16 vp_modern_get_num_queues(struct virtio_pci_modern_device *mdev)
+{
+	return vp_ioread16(&mdev->common->num_queues);
+}
+EXPORT_SYMBOL_GPL(vp_modern_get_num_queues);
+
+/*
+ * vp_modern_get_queue_notify_off - get notification offset for a virtqueue
+ * @mdev: the modern virtio-pci device
+ * @index: the queue index
+ *
+ * Returns the notification offset for a virtqueue
+ */
+u16 vp_modern_get_queue_notify_off(struct virtio_pci_modern_device *mdev,
+				   u16 index)
+{
+	vp_iowrite16(index, &mdev->common->queue_select);
+
+	return vp_ioread16(&mdev->common->queue_notify_off);
+}
+EXPORT_SYMBOL_GPL(vp_modern_get_queue_notify_off);
+
+MODULE_VERSION("0.1");
+MODULE_DESCRIPTION("Modern Virtio PCI Device");
+MODULE_AUTHOR("Jason Wang <[e-mail]>");
+MODULE_LICENSE("GPL");

include/linux/virtio_pci_modern.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_VIRTIO_PCI_MODERN_H
+#define _LINUX_VIRTIO_PCI_MODERN_H
+
+#include <linux/pci.h>
+#include <linux/virtio_pci.h>
+
+struct virtio_pci_modern_device {
+	struct pci_dev *pci_dev;
+
+	struct virtio_pci_common_cfg __iomem *common;
+	/* Device-specific data (non-legacy mode)  */
+	void __iomem *device;
+	/* Base of vq notifications (non-legacy mode). */
+	void __iomem *notify_base;
+	/* Where to read and clear interrupt */
+	u8 __iomem *isr;
+
+	/* So we can sanity-check accesses. */
+	size_t notify_len;
+	size_t device_len;
+
+	/* Capability for when we need to map notifications per-vq. */
+	int notify_map_cap;
+
+	/* Multiply queue_notify_off by this value. (non-legacy mode). */
+	u32 notify_offset_multiplier;
+
+	int modern_bars;
+
+	struct virtio_device_id id;
+};
+
+/*
+ * Type-safe wrappers for io accesses.
+ * Use these to enforce at compile time the following spec requirement:
+ *
+ * The driver MUST access each field using the “natural” access
+ * method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses
+ * for 16-bit fields and 8-bit accesses for 8-bit fields.
+ */
+static inline u8 vp_ioread8(const u8 __iomem *addr)
+{
+	return ioread8(addr);
+}
+static inline u16 vp_ioread16 (const __le16 __iomem *addr)
+{
+	return ioread16(addr);
+}
+
+static inline u32 vp_ioread32(const __le32 __iomem *addr)
+{
+	return ioread32(addr);
+}
+
+static inline void vp_iowrite8(u8 value, u8 __iomem *addr)
+{
+	iowrite8(value, addr);
+}
+
+static inline void vp_iowrite16(u16 value, __le16 __iomem *addr)
+{
+	iowrite16(value, addr);
+}
+
+static inline void vp_iowrite32(u32 value, __le32 __iomem *addr)
+{
+	iowrite32(value, addr);
+}
+
+static inline void vp_iowrite64_twopart(u64 val,
+					__le32 __iomem *lo,
+					__le32 __iomem *hi)
+{
+	vp_iowrite32((u32)val, lo);
+	vp_iowrite32(val >> 32, hi);
+}
+
+u64 vp_modern_get_features(struct virtio_pci_modern_device *mdev);
+void vp_modern_set_features(struct virtio_pci_modern_device *mdev,
+		     u64 features);
+u32 vp_modern_generation(struct virtio_pci_modern_device *mdev);
+u8 vp_modern_get_status(struct virtio_pci_modern_device *mdev);
+void vp_modern_set_status(struct virtio_pci_modern_device *mdev,
+		   u8 status);
+u16 vp_modern_queue_vector(struct virtio_pci_modern_device *mdev,
+			   u16 idx, u16 vector);
+u16 vp_modern_config_vector(struct virtio_pci_modern_device *mdev,
+		     u16 vector);
+void vp_modern_queue_address(struct virtio_pci_modern_device *mdev,
+			     u16 index, u64 desc_addr, u64 driver_addr,
+			     u64 device_addr);
+void vp_modern_set_queue_enable(struct virtio_pci_modern_device *mdev,
+				u16 idx, bool enable);
+bool vp_modern_get_queue_enable(struct virtio_pci_modern_device *mdev,
+				u16 idx);
+void vp_modern_set_queue_size(struct virtio_pci_modern_device *mdev,
+			      u16 idx, u16 size);
+u16 vp_modern_get_queue_size(struct virtio_pci_modern_device *mdev,
+			     u16 idx);
+u16 vp_modern_get_num_queues(struct virtio_pci_modern_device *mdev);
+u16 vp_modern_get_queue_notify_off(struct virtio_pci_modern_device *mdev,
+				   u16 idx);
+void __iomem *vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
+				       size_t minlen,
+				       u32 align,
+				       u32 start, u32 size,
+				       size_t *len);
+int vp_modern_probe(struct virtio_pci_modern_device *mdev);
+void vp_modern_remove(struct virtio_pci_modern_device *mdev);
+#endif