Commit e021e6cb authored by Yunxiang Li's avatar Yunxiang Li Committed by Alex Williamson
Browse files

vfio/pci: Expose setup ROM at ROM bar when needed 



If ROM bar is missing for any reason, we can fallback to using pdev->rom
to expose the ROM content to the guest. This fixes some passthrough use
cases where the upstream bridge does not have enough address window.

Signed-off-by: default avatarYunxiang Li <Yunxiang.Li@amd.com>
Link: https://lore.kernel.org/r/20250102185013.15082-3-Yunxiang.Li@amd.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent c5a8b5d7

drivers/vfio/pci/vfio_pci_config.c

+4 −0
Original line number Diff line number Diff line
@@ -511,6 +511,10 @@ static void vfio_bar_fixup(struct vfio_pci_core_device *vdev) 
		mask = ~(pci_resource_len(pdev, PCI_ROM_RESOURCE) - 1);

		mask |= PCI_ROM_ADDRESS_ENABLE;

		*vbar &= cpu_to_le32((u32)mask);

	} else if (pdev->rom && pdev->romlen) {

		mask = ~(roundup_pow_of_two(pdev->romlen) - 1);

		mask |= PCI_ROM_ADDRESS_ENABLE;

		*vbar &= cpu_to_le32((u32)mask);

	} else {

		*vbar = 0;

	}

drivers/vfio/pci/vfio_pci_core.c

+18 −16
Original line number Diff line number Diff line
@@ -1054,25 +1054,27 @@ static int vfio_pci_ioctl_get_region_info(struct vfio_pci_core_device *vdev, 


		info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);

		info.flags = 0;

		info.size = 0;



		/* Report the BAR size, not the ROM size */

		info.size = pci_resource_len(pdev, info.index);

		if (!info.size)

			break;



		if (pci_resource_start(pdev, PCI_ROM_RESOURCE)) {

			/*

		 * Is it really there?  Enable memory decode for implicit access

		 * in pci_map_rom().

			 * Check ROM content is valid. Need to enable memory

			 * decode for ROM access in pci_map_rom().

			 */

			cmd = vfio_pci_memory_lock_and_enable(vdev);

			io = pci_map_rom(pdev, &size);

			if (io) {

				info.flags = VFIO_REGION_INFO_FLAG_READ;

				/* Report the BAR size, not the ROM size. */

				info.size = pci_resource_len(pdev, PCI_ROM_RESOURCE);

				pci_unmap_rom(pdev, io);

		} else {

			info.size = 0;

			}

			vfio_pci_memory_unlock_and_restore(vdev, cmd);

		} else if (pdev->rom && pdev->romlen) {

			info.flags = VFIO_REGION_INFO_FLAG_READ;

			/* Report BAR size as power of two. */

			info.size = roundup_pow_of_two(pdev->romlen);

		}



		break;

	}

drivers/vfio/pci/vfio_pci_rdwr.c

+16 −6
Original line number Diff line number Diff line
@@ -237,6 +237,8 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_core_device *vdev, char __user *buf, 


	if (pci_resource_start(pdev, bar))

		end = pci_resource_len(pdev, bar);

	else if (bar == PCI_ROM_RESOURCE && pdev->rom && pdev->romlen)

		end = roundup_pow_of_two(pdev->romlen);

	else

		return -EINVAL;
@@ -251,11 +253,14 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_core_device *vdev, char __user *buf, 
		 * excluded range at the end of the actual ROM.  This makes

		 * filling large ROM BARs much faster.

		 */

		if (pci_resource_start(pdev, bar)) {

			io = pci_map_rom(pdev, &x_start);

		if (!io) {

			done = -ENOMEM;

			goto out;

		} else {

			io = ioremap(pdev->rom, pdev->romlen);

			x_start = pdev->romlen;

		}

		if (!io)

			return -ENOMEM;

		x_end = end;

	} else {

		int ret = vfio_pci_core_setup_barmap(vdev, bar);
@@ -278,8 +283,13 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_core_device *vdev, char __user *buf, 
	if (done >= 0)

		*ppos += done;



	if (bar == PCI_ROM_RESOURCE)

	if (bar == PCI_ROM_RESOURCE) {

		if (pci_resource_start(pdev, bar))

			pci_unmap_rom(pdev, io);

		else

			iounmap(io);

	}



out:

	return done;

}