Re: [PATCH v2] vfio/pci: Use a private flag to prevent power state change with VFs

[Alex Williamson]

On Thu, 14 May 2026 17:34:49 +0000
Raghavendra Rao Ananta <rananta@xxxxxxxxxx> wrote:

> The current implementation uses pci_num_vf() while holding the
> memory_lock to prevent changing the power state of a PF when
> VFs are enabled. This creates a lockdep circular dependency
> warning because memory_lock is held during device probing.
> 
...
> 
> Introduce a private flag 'sriov_active' in the vfio_pci_core_device
> struct. This  allows the driver to track the SR-IOV power state requirement
> without  relying on pci_num_vf() while holding the memory_lock. The lock is
> now  only held to set the flag and ensure the device is in D0, after which
> pci_enable_sriov() can be called without the lock.
> 
> Fixes: f4162eb1e2fc ("vfio/pci: Change the PF power state to D0 before enabling VFs")
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx>
> Suggested-by: Alex Williamson <alex@xxxxxxxxxxx>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 17 ++++++++++++++---
>  include/linux/vfio_pci_core.h    |  1 +
>  2 files changed, 15 insertions(+), 3 deletions(-)

Applied to vfio next branch for v7.2, with the noted bitfield
conversion.  Thanks,

Alex