vfio_pci_dev_set_needs_reset() inspects the open_count of every device
in the set to determine whether a reset is needed. The current device
always has open_count == 1 within vfio_pci_core_disable(), effectively
disabling the reset logic. This field is also documented as private in
vfio_device, so it should not be used to determine whether other devices
in the set are open.
Checking for open_count > 1 on the device set fixes both issues.
After commit 2cd8b14aaa66 ("vfio/pci: Move to the device set
infrastructure"), failure to create a new file for a device would cause
the reset to be skipped due to open_count being decremented after
calling close_device() in the error path.
After commit eadd86f835c6 ("vfio: Remove calls to
vfio_group_add_container_user()"), releasing a device would always skip
the reset due to an ordering change in vfio_device_fops_release().
Failing to reset the device leaves it in an unknown state, potentially
causing errors when it is bound to a different driver.
This issue was observed with a Radeon RX Vega 56 [1002:687f] (rev c3)
assigned to a Windows guest. After shutting down the guest, unbinding
the device from vfio-pci, and binding the device to amdgpu:
[ 548.007102] [drm:psp_hw_start [amdgpu]] *ERROR* PSP create ring failed!
[ 548.027174] [drm:psp_hw_init [amdgpu]] *ERROR* PSP firmware loading failed
[ 548.027242] [drm:amdgpu_device_fw_loading [amdgpu]] *ERROR* hw_init of IP block <psp> failed -22
[ 548.027306] amdgpu 0000:0a:00.0: amdgpu: amdgpu_device_ip_init failed
[ 548.027308] amdgpu 0000:0a:00.0: amdgpu: Fatal error during GPU init
Fixes: 2cd8b14aaa66 ("vfio/pci: Move to the device set infrastructure")
Fixes: eadd86f835c6 ("vfio: Remove calls to vfio_group_add_container_user()")
Signed-off-by: Anthony DeRossi <ajderossi@xxxxxxxxx>
---
drivers/vfio/pci/vfio_pci_core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index badc9d828cac..e65c70781fe2 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -2488,12 +2488,12 @@ static bool vfio_pci_dev_set_needs_reset(struct vfio_device_set *dev_set)
struct vfio_pci_core_device *cur;
bool needs_reset = false;
- list_for_each_entry(cur, &dev_set->device_list, vdev.dev_set_list) {
- /* No VFIO device in the set can have an open device FD */
- if (cur->vdev.open_count)
- return false;
+ /* No other VFIO device in the set can be open. */
+ if (dev_set->open_count > 1)
+ return false;
+
+ list_for_each_entry(cur, &dev_set->device_list, vdev.dev_set_list)
needs_reset |= cur->needs_reset;
- }
return needs_reset;
}
--
2.37.4
