From: Karl Mehltretter <kmehltretter@gmail.com>
To: sashiko-reviews@lists.linux.dev
Cc: "Karl Mehltretter" <kmehltretter@gmail.com>,
"Rob Clark" <robin.clark@oss.qualcomm.com>,
sashiko-bot@kernel.org, dri-devel@lists.freedesktop.org,
linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org,
"Jianfeng Liu" <liujianfeng1994@gmail.com>,
"Christian König" <christian.koenig@amd.com>,
"Dmitry Baryshkov" <lumag@kernel.org>,
"Abhinav Kumar" <abhinav.kumar@linux.dev>,
"Jessica Zhang" <jesszhan0024@gmail.com>,
"Sean Paul" <sean@poorly.run>,
"Marijn Suijten" <marijn.suijten@somainline.org>,
"David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>,
linux-kernel@vger.kernel.org
Subject: Re: [RFT 3/5] drm/msm: Extract out map/unmap helpers
Date: Wed, 7 Oct 2026 07:19:24 +0200 [thread overview]
Message-ID: <20261007051924.39963-1-kmehltretter@gmail.com> (raw)
In-Reply-To: <20261006131920.6870D1F000FF@smtp.kernel.org>
> Does this error path miss an IOTLB flush?
Yes. msm_iommu_pagetable_unmap() called iommu_flush_iotlb_all() after
rollback. __do_map() now calls __do_unmap() directly and loses that
flush.
An arm64 QEMU/SMMUv3 test:
- mapped one 4 KiB page,
- hit -EEXIST on the second page, and
- verified that rollback removed the first PTE.
No stale translation was observed because the device had not accessed
the mapping. This tested the low-level IOMMU sequence, not the MSM driver
or Qualcomm hardware.
Restoring iommu_flush_iotlb_all() on this error path preserves the old
behavior.
Karl
next prev parent reply other threads:[~2026-10-07 5:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-06 13:09 [RFT 0/5] drm/msm: DMABUF_DEBUG fixes Rob Clark
2026-10-06 13:09 ` [RFT 1/5] drm/msm: Cleanup if pages_to_sg() fails Rob Clark
2026-10-06 13:09 ` [RFT 2/5] drm/msm/gem: dma_map/unmap_sgtable() Rob Clark
2026-10-06 13:09 ` [RFT 3/5] drm/msm: Extract out map/unmap helpers Rob Clark
[not found] ` <20261006131920.6870D1F000FF@smtp.kernel.org>
2026-10-07 5:19 ` Karl Mehltretter [this message]
2026-10-06 13:09 ` [RFT 4/5] drm/msm: Convert iommu map/unmap to helpers Rob Clark
[not found] ` <20261006132545.8BFD51F000FF@smtp.kernel.org>
2026-10-07 5:23 ` Karl Mehltretter
2026-10-06 13:09 ` [RFT 5/5] drm/msm: Convert map helper to use dma-address Rob Clark
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