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vfio: Require that devices support DMA cache coherence

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IOMMU_CACHE means that normal DMAs do not require any additional coherency
mechanism and is the basic uAPI that VFIO exposes to userspace. For
instance VFIO applications like DPDK will not work if additional coherency
operations are required.

Therefore check IOMMU_CAP_CACHE_COHERENCY like vdpa & usnic do before
allowing an IOMMU backed VFIO device to be created.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v3-2cf356649677+a32-intel_no_snoop_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Jason Gunthorpe 2022-04-11 12:16:08 -03:00 committed by Joerg Roedel
parent f78dc1dad8
commit e8ae0e140c
1 changed files with 7 additions and 0 deletions
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7
drivers/vfio/vfio.c
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@ -815,6 +815,13 @@ static int __vfio_register_dev(struct vfio_device *device,
int vfio_register_group_dev(struct vfio_device *device)
{
/*
* VFIO always sets IOMMU_CACHE because we offer no way for userspace to
* restore cache coherency.
*/
if (!iommu_capable(device->dev->bus, IOMMU_CAP_CACHE_COHERENCY))
return -EINVAL;
return __vfio_register_dev(device,
vfio_group_find_or_alloc(device->dev));
}