From: "Mi, Dapeng1" <dapeng1.mi@intel.com>
To: David Stevens <stevensd@chromium.org>,
Robin Murphy <robin.murphy@arm.com>,
Will Deacon <will@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Tom Murphy <murphyt7@tcd.ie>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>
Subject: RE: [PATCH v3 5/5] dma-iommu: account for min_align_mask
Date: Wed, 11 Aug 2021 09:26:02 +0000 [thread overview]
Message-ID: <PH0PR11MB48249799E5C66534F9C37D8BCDF89@PH0PR11MB4824.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20210811024247.1144246-6-stevensd@google.com>
> -----Original Message-----
> From: iommu <iommu-bounces@lists.linux-foundation.org> On Behalf Of
> David Stevens
> Sent: Wednesday, August 11, 2021 10:43 AM
> To: Robin Murphy <robin.murphy@arm.com>; Will Deacon <will@kernel.org>
> Cc: linux-kernel@vger.kernel.org; Tom Murphy <murphyt7@tcd.ie>;
> iommu@lists.linux-foundation.org; David Stevens <stevensd@chromium.org>
> Subject: [PATCH v3 5/5] dma-iommu: account for min_align_mask
>
> 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 tht at 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 | 23 ++++++++++++-----------
> 1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 89b689bf801f..ffa7e8ef5db4 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -549,9 +549,8 @@ static dma_addr_t
> __iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
> 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 = org_size;
> - void *padding_start;
> - size_t padding_size;
> + void *tlb_start;
> + size_t aligned_size, iova_off, mapping_end_off;
> dma_addr_t iova;
>
> /*
> @@ -566,24 +565,26 @@ static dma_addr_t
> __iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
> 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);
>
> + /* Cleanup the padding area. */
> if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
> (dir == DMA_TO_DEVICE ||
> dir == DMA_BIDIRECTIONAL)) {
> - padding_start += org_size;
> - padding_size -= org_size;
> + mapping_end_off = iova_off + org_size;
> + memset(tlb_start, 0, iova_off);
> + memset(tlb_start + mapping_end_off, 0,
> + aligned_size - mapping_end_off);
> + } else {
> + memset(tlb_start, 0, aligned_size);
> }
Nice fix. It's better move the "cleanup ..." comment into if case which looks more accurate.
next prev parent reply other threads:[~2021-08-11 9:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-11 2:42 [PATCH v3 0/5] Fixes for dma-iommu swiotlb bounce buffers David Stevens
2021-08-11 2:42 ` [PATCH v3 1/5] dma-iommu: fix sync_sg with swiotlb David Stevens
2021-08-11 5:57 ` Christoph Hellwig
2021-08-11 18:22 ` Robin Murphy
2021-08-11 2:42 ` [PATCH v3 2/5] dma-iommu: fix arch_sync_dma for map David Stevens
2021-08-11 6:01 ` Christoph Hellwig
2021-08-11 18:47 ` Robin Murphy
2021-08-12 9:21 ` David Stevens
2021-08-12 10:38 ` Robin Murphy
2021-08-11 2:42 ` [PATCH v3 3/5] dma-iommu: add SKIP_CPU_SYNC after syncing David Stevens
2021-08-11 6:07 ` Christoph Hellwig
2021-08-11 19:00 ` Robin Murphy
2021-08-11 2:42 ` [PATCH v3 4/5] dma-iommu: Check CONFIG_SWIOTLB more broadly David Stevens
2021-08-11 19:02 ` Robin Murphy
2021-08-11 2:42 ` [PATCH v3 5/5] dma-iommu: account for min_align_mask David Stevens
2021-08-11 9:26 ` Mi, Dapeng1 [this message]
2021-08-11 19:12 ` Robin Murphy
2021-08-12 1:45 ` David Stevens
2021-08-12 9:57 ` Robin Murphy
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=PH0PR11MB48249799E5C66534F9C37D8BCDF89@PH0PR11MB4824.namprd11.prod.outlook.com \
--to=dapeng1.mi@intel.com \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=murphyt7@tcd.ie \
--cc=robin.murphy@arm.com \
--cc=stevensd@chromium.org \
--cc=will@kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).