Re: [libvirt] [RFC PATCH 3/9] vfio/pci: register a default migration region

Vendor driver specifies when to support a migration region through cap VFIO_PCI_DEVICE_CAP_MIGRATION in vfio_pci_mediate_ops->open(). If vfio-pci detects this cap, it creates a default migration region on behalf of vendor driver with region len=0 and region->ops=null. Vendor driver should override this region's len, flags, rw, mmap in its vfio_pci_mediate_ops. This migration region definition is aligned to QEMU vfio migration code v8: (https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg05542.html) Cc: Kevin Tian <kevin.tian(a)intel.com&gt; Signed-off-by: Yan Zhao <yan.y.zhao(a)intel.com&gt; --- drivers/vfio/pci/vfio_pci.c | 15 ++++ include/linux/vfio.h | 1 + include/uapi/linux/vfio.h | 149 ++++++++++++++++++++++++++++++++++++ 3 files changed, 165 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index f3730252ee82..059660328be2 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -115,6 +115,18 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev) return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA; } +/** + * init a region to hold migration ctl & data + */ +void init_migration_region(struct vfio_pci_device *vdev) +{ + vfio_pci_register_dev_region(vdev, VFIO_REGION_TYPE_MIGRATION, + VFIO_REGION_SUBTYPE_MIGRATION, + NULL, 0, + VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_WRITE, + NULL); +} + static void vfio_pci_probe_mmaps(struct vfio_pci_device *vdev) { struct resource *res; @@ -523,6 +535,9 @@ static int vfio_pci_open(void *device_data) vdev->mediate_ops = mentry->ops; vdev->mediate_handle = handle; + if (caps & VFIO_PCI_DEVICE_CAP_MIGRATION) + init_migration_region(vdev);

+ pr_info("vfio pci found mediate_ops %s, caps=%llx, handle=%x for %x:%x\n", vdev->mediate_ops->name, caps, handle, vdev->pdev->vendor,