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[v7,05/11] PCI: pci_stub: Set driver_managed_dma

Message ID 20220228005056.599595-6-baolu.lu@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series Fix BUG_ON in vfio_iommu_group_notifier() | expand

Commit Message

Baolu Lu Feb. 28, 2022, 12:50 a.m. UTC 
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 <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/pci/pci-stub.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Bjorn Helgaas Feb. 28, 2022, 7:54 p.m. UTC | #1 
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 <baolu.lu@linux.intel.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  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
> 
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
diff mbox series

Patch

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)