Messages in this thread | | | From | "Zhang, Tina" <> | Subject | RE: [PATCH] iommu/vt-d: check alignment before using psi | Date | Fri, 18 Mar 2022 06:10:12 +0000 |
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> -----Original Message----- > From: iommu <iommu-bounces@lists.linux-foundation.org> On Behalf Of > David Stevens > Sent: Wednesday, March 16, 2022 1:07 PM > To: Lu Baolu <baolu.lu@linux.intel.com> > Cc: iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org; David > Stevens <stevensd@chromium.org> > Subject: [PATCH] iommu/vt-d: check alignment before using psi > > From: David Stevens <stevensd@chromium.org> > > Fall back to domain selective flush if the target address is not aligned to the > mask being used for invalidation. This is necessary because page selective > invalidation masks out the lower order bits of the target address based on > the mask value, so if a non-aligned address is targeted for psi, then mappings > at the end of [pfn, pfn+pages) may not properly be flushed from the iotlb. > > This is not normally an issue because iova.c always allocates iovas that are > aligned to their size. However, iovas which come from other sources (e.g. > userspace via VFIO) may not be aligned.
Indeed, the dma_map/unmap always use alloca_iova(..., true) to allocate iova, which means size_aligned. But the iova used by userspace might not be size aligned. And it seems we cannot expect userspace can always use size_aligned iova base address.
BR, Tina
> > Signed-off-by: David Stevens <stevensd@chromium.org> > --- > drivers/iommu/intel/iommu.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > index 5b196cfe9ed2..c122686e0a5c 100644 > --- a/drivers/iommu/intel/iommu.c > +++ b/drivers/iommu/intel/iommu.c > @@ -1735,7 +1735,8 @@ static void iommu_flush_iotlb_psi(struct > intel_iommu *iommu, > * and the base address is naturally aligned to the size. > */ > if (!cap_pgsel_inv(iommu->cap) || > - mask > cap_max_amask_val(iommu->cap)) > + mask > cap_max_amask_val(iommu->cap) || > + unlikely(((1 << mask) - 1) & pfn)) > iommu->flush.flush_iotlb(iommu, did, 0, 0, > > DMA_TLB_DSI_FLUSH); > else > -- > 2.35.1.723.g4982287a31-goog > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu
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