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vfio: add read/write to device IO ops vector

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Now we have the region info cache, add ->region_read/write device I/O
operations instead of explicit pread()/pwrite() system calls.

Signed-off-by: John Levon <john.levon@nutanix.com>
Link: https://lore.kernel.org/qemu-devel/20250507152020.1254632-13-john.levon@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
This commit is contained in:
John Levon 2025-05-07 16:20:17 +01:00 • committed by Cédric Le Goater
parent 95cdb02451
commit 776066ac90
4 changed files with 77 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

34
hw/vfio/device.c
View file

@ -505,9 +505,43 @@ static int vfio_device_io_set_irqs(VFIODevice *vbasedev,
return ret < 0 ? -errno : ret;
}
static int vfio_device_io_region_read(VFIODevice *vbasedev, uint8_t index,
off_t off, uint32_t size, void *data)
{
struct vfio_region_info *info;
int ret;
ret = vfio_device_get_region_info(vbasedev, index, &info);
if (ret != 0) {
return ret;
}
ret = pread(vbasedev->fd, data, size, info->offset + off);
return ret < 0 ? -errno : ret;
}
static int vfio_device_io_region_write(VFIODevice *vbasedev, uint8_t index,
off_t off, uint32_t size, void *data)
{
struct vfio_region_info *info;
int ret;
ret = vfio_device_get_region_info(vbasedev, index, &info);
if (ret != 0) {
return ret;
}
ret = pwrite(vbasedev->fd, data, size, info->offset + off);
return ret < 0 ? -errno : ret;
}
static VFIODeviceIOOps vfio_device_io_ops_ioctl = {
.device_feature = vfio_device_io_device_feature,
.get_region_info = vfio_device_io_get_region_info,
.get_irq_info = vfio_device_io_get_irq_info,
.set_irqs = vfio_device_io_set_irqs,
.region_read = vfio_device_io_region_read,
.region_write = vfio_device_io_region_write,
};

28
hw/vfio/pci.c
View file

@ -918,18 +918,22 @@ static void vfio_pci_load_rom(VFIOPCIDevice *vdev)
memset(vdev->rom, 0xff, size);
while (size) {
bytes = pread(vbasedev->fd, vdev->rom + off,
size, vdev->rom_offset + off);
bytes = vbasedev->io_ops->region_read(vbasedev,
VFIO_PCI_ROM_REGION_INDEX,
off, size, vdev->rom + off);
if (bytes == 0) {
break;
} else if (bytes > 0) {
off += bytes;
size -= bytes;
} else {
if (errno == EINTR || errno == EAGAIN) {
if (bytes == -EINTR || bytes == -EAGAIN) {
continue;
}
error_report("vfio: Error reading device ROM: %m");
error_report("vfio: Error reading device ROM: %s",
strreaderror(bytes));
break;
}
}
@ -969,22 +973,18 @@ static void vfio_pci_load_rom(VFIOPCIDevice *vdev)
static int vfio_pci_config_space_read(VFIOPCIDevice *vdev, off_t offset,
uint32_t size, void *data)
{
ssize_t ret;
ret = pread(vdev->vbasedev.fd, data, size, vdev->config_offset + offset);
return ret < 0 ? -errno : (int)ret;
return vdev->vbasedev.io_ops->region_read(&vdev->vbasedev,
VFIO_PCI_CONFIG_REGION_INDEX,
offset, size, data);
}
/* "Raw" write of underlying config space. */
static int vfio_pci_config_space_write(VFIOPCIDevice *vdev, off_t offset,
uint32_t size, void *data)
{
ssize_t ret;
ret = pwrite(vdev->vbasedev.fd, data, size, vdev->config_offset + offset);
return ret < 0 ? -errno : (int)ret;
return vdev->vbasedev.io_ops->region_write(&vdev->vbasedev,
VFIO_PCI_CONFIG_REGION_INDEX,
offset, size, data);
}
static uint64_t vfio_rom_read(void *opaque, hwaddr addr, unsigned size)

17
hw/vfio/region.c
View file

@ -45,6 +45,7 @@ void vfio_region_write(void *opaque, hwaddr addr,
uint32_t dword;
uint64_t qword;
} buf;
int ret;
switch (size) {
case 1:
@ -64,11 +65,13 @@ void vfio_region_write(void *opaque, hwaddr addr,
break;
}
if (pwrite(vbasedev->fd, &buf, size, region->fd_offset + addr) != size) {
ret = vbasedev->io_ops->region_write(vbasedev, region->nr,
addr, size, &buf);
if (ret != size) {
error_report("%s(%s:region%d+0x%"HWADDR_PRIx", 0x%"PRIx64
",%d) failed: %m",
",%d) failed: %s",
__func__, vbasedev->name, region->nr,
addr, data, size);
addr, data, size, strwriteerror(ret));
}
trace_vfio_region_write(vbasedev->name, region->nr, addr, data, size);
@ -96,11 +99,13 @@ uint64_t vfio_region_read(void *opaque,
uint64_t qword;
} buf;
uint64_t data = 0;
int ret;
if (pread(vbasedev->fd, &buf, size, region->fd_offset + addr) != size) {
error_report("%s(%s:region%d+0x%"HWADDR_PRIx", %d) failed: %m",
ret = vbasedev->io_ops->region_read(vbasedev, region->nr, addr, size, &buf);
if (ret != size) {
error_report("%s(%s:region%d+0x%"HWADDR_PRIx", %d) failed: %s",
__func__, vbasedev->name, region->nr,
addr, size);
addr, size, strreaderror(ret));
return (uint64_t)-1;
}
switch (size) {

18
include/hw/vfio/vfio-device.h
View file

@ -188,6 +188,24 @@ struct VFIODeviceIOOps {
* Configure IRQs as defined by @irqs.
*/
int (*set_irqs)(VFIODevice *vdev, struct vfio_irq_set *irqs);
/**
* @region_read
*
* Read @size bytes from the region @nr at offset @off into the buffer
* @data.
*/
int (*region_read)(VFIODevice *vdev, uint8_t nr, off_t off, uint32_t size,
void *data);
/**
* @region_write
*
* Write @size bytes to the region @nr at offset @off from the buffer
* @data.
*/
int (*region_write)(VFIODevice *vdev, uint8_t nr, off_t off, uint32_t size,
void *data);
};
void vfio_device_prepare(VFIODevice *vbasedev, VFIOContainerBase *bcontainer,