On Mon, Feb 28, 2022 at 08:50:50AM +0800, Lu Baolu wrote:
> The current VFIO implementation allows pci-stub driver to be bound to
> a PCI device with other devices in the same IOMMU group being assigned
> to userspace. The pci-stub driver has no dependencies on DMA or the
> IOVA mapping of the device, but it does prevent the user from having
> direct access to the device, which is useful in some circumstances.
>
> The pci_dma_configure() marks the iommu_group as containing only devices
> with kernel drivers that manage DMA. For compatibility with the VFIO
> usage, avoid this default behavior for the pci_stub. This allows the
> pci_stub still able to be used by the admin to block driver binding after
> applying the DMA ownership to VFIO.
>
> Signed-off-by: Lu Baolu
> Reviewed-by: Jason Gunthorpe
Acked-by: Bjorn Helgaas
> ---
> drivers/pci/pci-stub.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/pci/pci-stub.c b/drivers/pci/pci-stub.c
> index e408099fea52..d1f4c1ce7bd1 100644
> --- a/drivers/pci/pci-stub.c
> +++ b/drivers/pci/pci-stub.c
> @@ -36,6 +36,7 @@ static struct pci_driver stub_driver = {
> .name = "pci-stub",
> .id_table = NULL, /* only dynamic id's */
> .probe = pci_stub_probe,
> + .driver_managed_dma = true,
> };
>
> static int __init pci_stub_init(void)
> --
> 2.25.1
>
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