Re: [PATCH RFC 08/12] iommufd: IOCTLs for the io_pagetable

[Jason Gunthorpe via iommu <iommu@lists.linux-foundation.org>]

On Mon, Mar 28, 2022 at 03:57:53PM -0300, Jason Gunthorpe wrote:

> So, currently AMD and Intel have exactly the same HW feature with a
> different kAPI..

I fixed it like below and made the ordering changes Kevin pointed
to. Will send next week after the merge window:

527e438a974a06 iommu: Delete IOMMU_CAP_CACHE_COHERENCY
5cbc8603ffdf20 vfio: Move the Intel no-snoop control off of IOMMU_CACHE
ebc961f93d1af3 iommu: Introduce the domain op enforce_cache_coherency()
79c52a2bb1e60b vfio: Require that devices support DMA cache coherence
02168f961b6a75 iommu: Replace uses of IOMMU_CAP_CACHE_COHERENCY with dev_is_dma_coherent()

'79c can be avoided, we'd just drive IOMMU_CACHE off of
dev_is_dma_coherent() - but if we do that I'd like to properly
document the arch/iommu/platform/kvm combination that is using this..

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 3c0ac3c34a7f9a..f144eb9fea8e31 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2269,6 +2269,12 @@ static int amd_iommu_def_domain_type(struct device *dev)
 	return 0;
 }
 
+static bool amd_iommu_enforce_cache_coherency(struct iommu_domain *domain)
+{
+	/* IOMMU_PTE_FC is always set */
+	return true;
+}
+
 const struct iommu_ops amd_iommu_ops = {
 	.capable = amd_iommu_capable,
 	.domain_alloc = amd_iommu_domain_alloc,
@@ -2291,6 +2297,7 @@ const struct iommu_ops amd_iommu_ops = {
 		.flush_iotlb_all = amd_iommu_flush_iotlb_all,
 		.iotlb_sync	= amd_iommu_iotlb_sync,
 		.free		= amd_iommu_domain_free,
+		.enforce_cache_coherency = amd_iommu_enforce_cache_coherency,
 	}
 };

Thanks,
Jason
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