[RFC PATCH 1/1] vfio/pci: Disable sriov on PF device close

[Samiullah Khawaja <skhawaja@google.com>]

When userspace closes a VFIO device file descriptor, the vfio driver
performs a hardware reset on the PCIe device to ensure it is returned to
a clean state. However, if the closed device is an SR-IOV Physical
Function (PF), it may have instantiated Virtual Functions (VFs) that are
actively bound to host kernel drivers (or other vfio instances).

When the PF is hardware-reset via VFIO, it implicitly disrupts SR-IOV
operations at the device level. Because this reset happens without notifying
the core PCI driver model, the kernel drivers bound to the VFs remain loaded
and operate under the assumption that the VF hardware is still functional.

This creates a state mismatch between the kernel's view of the hardware
and the actual device state. Subsequent attempts by the host OS or bound
drivers to interact with the VFs will fail, leading to unexpected
errors.

Disable SR-IOV on the device prior to issuing the PF reset so that the
VFs can teardown and remove at the software level also.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 drivers/vfio/pci/vfio_pci_core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index a113c55845e1..b36c77eb3c40 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -826,6 +826,13 @@ void vfio_pci_core_close_device(struct vfio_device *core_vdev)
 #if IS_ENABLED(CONFIG_EEH)
 	eeh_dev_release(vdev->pdev);
 #endif
+
+	if (pci_num_vf(vdev->pdev)) {
+		device_lock(&vdev->pdev->dev);
+		vfio_pci_core_sriov_configure(vdev, 0);
+		device_unlock(&vdev->pdev->dev);
+	}
+
 	vfio_pci_dma_buf_cleanup(vdev);
 
 	vfio_pci_core_disable(vdev);
-- 
2.55.0.629.g250fe7f194-goog