vfio/virtio: Enable support for virtio-block live migration

JIRA: https://issues.redhat.com/browse/RHEL-85587

commit 384a530
Author: Yishai Hadas <yishaih@nvidia.com>
Date:   Sun Mar 2 18:27:23 2025 +0200

    vfio/virtio: Enable support for virtio-block live migration

    With a functional and tested backend for virtio-block live migration,
    add the virtio-block device ID to the pci_device_id table.

    Currently, the driver supports legacy IO functionality only for
    virtio-net, and it is accounted for in specific parts of the code.

    To enforce this limitation, an explicit check for virtio-net, has been
    added in virtiovf_support_legacy_io(). Once a backend implements legacy
    IO functionality for virtio-block, the necessary support will be added
    to the driver, and this additional check should be removed.

    The module description was updated accordingly.

    Reviewed-by: Kevin Tian <kevin.tian@intel.com>
    Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
    Link: https://lore.kernel.org/r/20250302162723.82578-1-yishaih@nvidia.com
    Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Author: Alex Williamson

drivers/vfio/pci/virtio/Kconfig

@@ -1,11 +1,11 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config VIRTIO_VFIO_PCI
-	tristate "VFIO support for VIRTIO NET PCI VF devices"
+	tristate "VFIO support for VIRTIO PCI VF devices"
 	depends on VIRTIO_PCI
 	select VFIO_PCI_CORE
 	help
-	  This provides migration support for VIRTIO NET PCI VF devices
-	  using the VFIO framework. Migration support requires the
+	  This provides migration support for VIRTIO NET and BLOCK PCI VF
+	  devices using the VFIO framework. Migration support requires the
 	  SR-IOV PF device to support specific VIRTIO extensions,
 	  otherwise this driver provides no additional functionality
 	  beyond vfio-pci.

drivers/vfio/pci/virtio/legacy_io.c

@@ -382,7 +382,9 @@ static bool virtiovf_bar0_exists(struct pci_dev *pdev)
 
 bool virtiovf_support_legacy_io(struct pci_dev *pdev)
 {
-	return virtio_pci_admin_has_legacy_io(pdev) && !virtiovf_bar0_exists(pdev);
+	/* For now, the legacy IO functionality is supported only for virtio-net */
+	return pdev->device == 0x1041 && virtio_pci_admin_has_legacy_io(pdev) &&
+	       !virtiovf_bar0_exists(pdev);
 }
 
 int virtiovf_init_legacy_io(struct virtiovf_pci_core_device *virtvdev)

drivers/vfio/pci/virtio/main.c

@@ -187,8 +187,9 @@ static void virtiovf_pci_remove(struct pci_dev *pdev)
 }
 
 static const struct pci_device_id virtiovf_pci_table[] = {
-	/* Only virtio-net is supported/tested so far */
+	/* Only virtio-net and virtio-block are supported/tested so far */
 	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_REDHAT_QUMRANET, 0x1041) },
+	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_REDHAT_QUMRANET, 0x1042) },
 	{}
 };
 
@@ -221,4 +222,4 @@ module_pci_driver(virtiovf_pci_driver);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Yishai Hadas <yishaih@nvidia.com>");
 MODULE_DESCRIPTION(
-	"VIRTIO VFIO PCI - User Level meta-driver for VIRTIO NET devices");
+	"VIRTIO VFIO PCI - User Level meta-driver for VIRTIO NET and BLOCK devices");