On 2021-06-07 19:25, Nadav Amit wrote:
From: Nadav Amit <na...@vmware.com>On virtual machines, software must flush the IOTLB after each page table entry update. The iommu_map_sg() code iterates through the given scatter-gather list and invokes iommu_map() for each element in the scatter-gather list, which calls into the vendor IOMMU driver through iommu_ops callback. As the result, a single sg mapping may lead to multiple IOTLB flushes. Fix this by adding amd_iotlb_sync_map() callback and flushing at this point after all sg mappings we set. This commit is followed and inspired by commit 933fcd01e97e2 ("iommu/vt-d: Add iotlb_sync_map callback"). Cc: Joerg Roedel <j...@8bytes.org> Cc: Will Deacon <w...@kernel.org> Cc: Jiajun Cao <caojia...@vmware.com> Cc: Robin Murphy <robin.mur...@arm.com> Cc: Lu Baolu <baolu...@linux.intel.com> Cc: iommu@lists.linux-foundation.org Cc: linux-ker...@vger.kernel.org Signed-off-by: Nadav Amit <na...@vmware.com> --- drivers/iommu/amd/iommu.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index 128f2e889ced..dd23566f1db8 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -2027,6 +2027,16 @@ static int amd_iommu_attach_device(struct iommu_domain *dom, return ret; }+static void amd_iommu_iotlb_sync_map(struct iommu_domain *dom,+ unsigned long iova, size_t size) +{ + struct protection_domain *domain = to_pdomain(dom); + struct io_pgtable_ops *ops = &domain->iop.iop.ops; + + if (ops->map)
Not too critical since you're only moving existing code around, but is ops->map ever not set? Either way the check ends up looking rather out-of-place here :/
It's not very clear what the original intent was - I do wonder whether it's supposed to be related to PAGE_MODE_NONE, but given that amd_iommu_map() has an explicit check and errors out early in that case, we'd never get here anyway. Possibly something to come back and clean up later?
Robin.
+ domain_flush_np_cache(domain, iova, size); +} + static int amd_iommu_map(struct iommu_domain *dom, unsigned long iova, phys_addr_t paddr, size_t page_size, int iommu_prot, gfp_t gfp) @@ -2045,10 +2055,8 @@ static int amd_iommu_map(struct iommu_domain *dom, unsigned long iova, if (iommu_prot & IOMMU_WRITE) prot |= IOMMU_PROT_IW;- if (ops->map) {+ if (ops->map) ret = ops->map(ops, iova, paddr, page_size, prot, gfp); - domain_flush_np_cache(domain, iova, page_size); - }return ret;} @@ -2249,6 +2257,7 @@ const struct iommu_ops amd_iommu_ops = { .attach_dev = amd_iommu_attach_device, .detach_dev = amd_iommu_detach_device, .map = amd_iommu_map, + .iotlb_sync_map = amd_iommu_iotlb_sync_map, .unmap = amd_iommu_unmap, .iova_to_phys = amd_iommu_iova_to_phys, .probe_device = amd_iommu_probe_device,
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