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[73.37.105.206]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-206aea38c91sm28345915ad.169.2024.09.05.05.50.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Sep 2024 05:50:05 -0700 (PDT) From: Rob Clark To: iommu@lists.linux.dev Cc: linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, Ashish Mhetre , Rob Clark , Will Deacon , Robin Murphy , Joerg Roedel , linux-arm-kernel@lists.infradead.org (moderated list:ARM SMMU DRIVERS), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] Revert "iommu/io-pgtable-arm: Optimise non-coherent unmap" Date: Thu, 5 Sep 2024 05:49:56 -0700 Message-ID: <20240905124956.84932-1-robdclark@gmail.com> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Rob Clark This reverts commit 85b715a334583488ad7fbd3001fe6fd617b7d4c0. It was causing gpu smmu faults on x1e80100. I _think_ what is causing this is the change in ordering of __arm_lpae_clear_pte() (dma_sync_single_for_device() on the pgtable memory) and io_pgtable_tlb_flush_walk(). I'm not entirely sure how this patch is supposed to work correctly in the face of other concurrent translations (to buffers unrelated to the one being unmapped(), because after the io_pgtable_tlb_flush_walk() we can have stale data read back into the tlb. Signed-off-by: Rob Clark --- drivers/iommu/io-pgtable-arm.c | 31 ++++++++++++++----------------- 1 file changed, 14 insertions(+), 17 deletions(-) diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index 16e51528772d..85261baa3a04 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -274,13 +274,13 @@ static void __arm_lpae_sync_pte(arm_lpae_iopte *ptep, int num_entries, sizeof(*ptep) * num_entries, DMA_TO_DEVICE); } -static void __arm_lpae_clear_pte(arm_lpae_iopte *ptep, struct io_pgtable_cfg *cfg, int num_entries) +static void __arm_lpae_clear_pte(arm_lpae_iopte *ptep, struct io_pgtable_cfg *cfg) { - for (int i = 0; i < num_entries; i++) - ptep[i] = 0; - if (!cfg->coherent_walk && num_entries) - __arm_lpae_sync_pte(ptep, num_entries, cfg); + *ptep = 0; + + if (!cfg->coherent_walk) + __arm_lpae_sync_pte(ptep, 1, cfg); } static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, @@ -653,28 +653,25 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, max_entries = ARM_LPAE_PTES_PER_TABLE(data) - unmap_idx_start; num_entries = min_t(int, pgcount, max_entries); - /* Find and handle non-leaf entries */ - for (i = 0; i < num_entries; i++) { - pte = READ_ONCE(ptep[i]); + while (i < num_entries) { + pte = READ_ONCE(*ptep); if (WARN_ON(!pte)) break; - if (!iopte_leaf(pte, lvl, iop->fmt)) { - __arm_lpae_clear_pte(&ptep[i], &iop->cfg, 1); + __arm_lpae_clear_pte(ptep, &iop->cfg); + if (!iopte_leaf(pte, lvl, iop->fmt)) { /* Also flush any partial walks */ io_pgtable_tlb_flush_walk(iop, iova + i * size, size, ARM_LPAE_GRANULE(data)); __arm_lpae_free_pgtable(data, lvl + 1, iopte_deref(pte, data)); + } else if (!iommu_iotlb_gather_queued(gather)) { + io_pgtable_tlb_add_page(iop, gather, iova + i * size, size); } - } - /* Clear the remaining entries */ - __arm_lpae_clear_pte(ptep, &iop->cfg, i); - - if (gather && !iommu_iotlb_gather_queued(gather)) - for (int j = 0; j < i; j++) - io_pgtable_tlb_add_page(iop, gather, iova + j * size, size); + ptep++; + i++; + } return i * size; } else if (iopte_leaf(pte, lvl, iop->fmt)) {