LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: David Stevens <stevensd@chromium.org>
To: Robin Murphy <robin.murphy@arm.com>, Christoph Hellwig <hch@lst.de>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Lu Baolu <baolu.lu@linux.intel.com>, Tom Murphy <murphyt7@tcd.ie>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	David Stevens <stevensd@chromium.org>
Subject: [PATCH v6 7/7] dma-iommu: account for min_align_mask
Date: Tue, 17 Aug 2021 10:38:52 +0900	[thread overview]
Message-ID: <20210817013852.3222824-8-stevensd@google.com> (raw)
In-Reply-To: <20210817013852.3222824-1-stevensd@google.com>

From: David Stevens <stevensd@chromium.org>

For devices which set min_align_mask, swiotlb preserves the offset of
the original physical address within that mask. Since __iommu_dma_map
accounts for non-aligned addresses, passing a non-aligned swiotlb
address with the swiotlb aligned size results in the offset being
accounted for twice in the size passed to iommu_map_atomic. The extra
page exposed to DMA is also not cleaned up by __iommu_dma_unmap, since
that function unmaps with the correct size. This causes mapping failures
if the iova gets reused, due to collisions in the iommu page tables.

To fix this, pass the original size to __iommu_dma_map, since that
function already handles alignment.

Additionally, when swiotlb returns non-aligned addresses, there is
padding at the start of the bounce buffer that needs to be cleared.

Fixes: 1f221a0d0dbf ("swiotlb: respect min_align_mask")
Signed-off-by: David Stevens <stevensd@chromium.org>
---
 drivers/iommu/dma-iommu.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 6738420fc081..f2fb360c2907 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -788,7 +788,6 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 	struct iommu_domain *domain = iommu_get_dma_domain(dev);
 	struct iommu_dma_cookie *cookie = domain->iova_cookie;
 	struct iova_domain *iovad = &cookie->iovad;
-	size_t aligned_size = size;
 	dma_addr_t iova, dma_mask = dma_get_mask(dev);
 
 	/*
@@ -796,8 +795,8 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 	 * page aligned, we don't need to use a bounce page.
 	 */
 	if (dev_use_swiotlb(dev) && iova_offset(iovad, phys | size)) {
-		void *padding_start;
-		size_t padding_size;
+		void *tlb_start;
+		size_t aligned_size, iova_off, mapping_end_off;
 
 		aligned_size = iova_align(iovad, size);
 		phys = swiotlb_tbl_map_single(dev, phys, size, aligned_size,
@@ -806,23 +805,26 @@ static dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 		if (phys == DMA_MAPPING_ERROR)
 			return DMA_MAPPING_ERROR;
 
-		/* Cleanup the padding area. */
-		padding_start = phys_to_virt(phys);
-		padding_size = aligned_size;
+		iova_off = iova_offset(iovad, phys);
+		tlb_start = phys_to_virt(phys - iova_off);
 
 		if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 		    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) {
-			padding_start += size;
-			padding_size -= size;
+			/* Cleanup the padding area. */
+			mapping_end_off = iova_off + size;
+			memset(tlb_start, 0, iova_off);
+			memset(tlb_start + mapping_end_off, 0,
+			       aligned_size - mapping_end_off);
+		} else {
+			/* Nothing was sync'ed, so clear the whole buffer. */
+			memset(tlb_start, 0, aligned_size);
 		}
-
-		memset(padding_start, 0, padding_size);
 	}
 
 	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 		arch_sync_dma_for_device(phys, size, dir);
 
-	iova = __iommu_dma_map(dev, phys, aligned_size, prot, dma_mask);
+	iova = __iommu_dma_map(dev, phys, size, prot, dma_mask);
 	if (iova == DMA_MAPPING_ERROR && is_swiotlb_buffer(phys))
 		swiotlb_tbl_unmap_single(dev, phys, size, dir, attrs);
 	return iova;
-- 
2.33.0.rc1.237.g0d66db33f3-goog


  parent reply	other threads:[~2021-08-17  1:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-17  1:38 [PATCH v6 0/7] Fixes for dma-iommu swiotlb bounce buffers David Stevens
2021-08-17  1:38 ` [PATCH v6 1/7] dma-iommu: fix sync_sg with swiotlb David Stevens
2021-08-17  1:38 ` [PATCH v6 2/7] dma-iommu: fix arch_sync_dma for map David Stevens
2021-08-19  8:59   ` Robin Murphy
2021-08-17  1:38 ` [PATCH v6 3/7] dma-iommu: skip extra sync during unmap w/swiotlb David Stevens
2021-08-19  8:59   ` Robin Murphy
2021-08-17  1:38 ` [PATCH v6 4/7] dma-iommu: fold _swiotlb helpers into callers David Stevens
2021-08-19  9:00   ` Robin Murphy
2021-08-17  1:38 ` [PATCH v6 5/7] dma-iommu: Check CONFIG_SWIOTLB more broadly David Stevens
2021-08-17  1:38 ` [PATCH v6 6/7] swiotlb: support aligned swiotlb buffers David Stevens
2021-08-17  1:38 ` David Stevens [this message]
2021-08-19  9:03   ` [PATCH v6 7/7] dma-iommu: account for min_align_mask Robin Murphy
2021-08-19 10:05     ` David Stevens

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210817013852.3222824-8-stevensd@google.com \
    --to=stevensd@chromium.org \
    --cc=baolu.lu@linux.intel.com \
    --cc=hch@lst.de \
    --cc=iommu@lists.linux-foundation.org \
    --cc=joro@8bytes.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=murphyt7@tcd.ie \
    --cc=robin.murphy@arm.com \
    --cc=will@kernel.org \
    --subject='Re: [PATCH v6 7/7] dma-iommu: account for min_align_mask' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).