Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider: - [Critical] drm/msm: skipped leaf IOTLB invalidation in msm_iommu_unmap() - [High] drm/msm: missing IOTLB flush on error rollback in msm_iommu_map() - [High] drm/msm: missing iotlb_sync_map call in msm_iommu_map() --
commit 65df32b670bbcd4a7d2a95abeebac540248b0bbd Author: Rob Clark <[email protected]> drm/msm: Convert iommu map/unmap to helpers This commit converts msm_iommu_map() and msm_iommu_unmap() to use the __do_map() and __do_unmap() helpers with callbacks that invoke domain->ops->map_pages() and domain->ops->unmap_pages() directly. > diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c > index 78c82f4a01b92..435736c8d7150 100644 > --- a/drivers/gpu/drm/msm/msm_iommu.c > +++ b/drivers/gpu/drm/msm/msm_iommu.c > @@ -731,12 +731,27 @@ static void msm_iommu_detach(struct msm_mmu *mmu) > iommu_detach_device(iommu->domain, mmu->dev); > } > > +static size_t > +__unmap_iommu(void *arg, u64 iova, size_t pgsize, size_t pgcount) > +{ > + struct iommu_domain *domain = arg; > + return domain->ops->unmap_pages(domain, iova, pgsize, pgcount, NULL); > +} > + > +static int > +__map_iommu(void *arg, phys_addr_t paddr, u64 iova, size_t pgsize, > + size_t pgcount, int prot, size_t *mapped) > +{ > + struct iommu_domain *domain = arg; > + return domain->ops->map_pages(domain, iova, paddr, pgsize, pgcount, > + prot, GFP_KERNEL, mapped); > +} > + > static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova, > struct sg_table *sgt, size_t off, size_t len, > int prot) > { > - struct msm_iommu *iommu = to_msm_iommu(mmu); > - ssize_t ret; > + struct iommu_domain *domain = to_msm_iommu(mmu)->domain; > > WARN_ON(off != 0); > > @@ -744,23 +759,23 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t > iova, > if (iova & BIT_ULL(48)) > iova |= GENMASK_ULL(63, 49); > > - ret = iommu_map_sgtable(iommu->domain, iova, sgt, prot); > - if (ret < 0) > - return ret; > - > - return (ret == len) ? 0 : -EINVAL; > + return __do_map(domain->pgsize_bitmap, iova, sgt, off, len, prot, > + domain, __map_iommu, __unmap_iommu); > } [Severity: High] Does msm_iommu_map() miss an IOTLB flush when __do_map() fails mid-way? If __map_iommu() fails after some pages have already been mapped, __do_map() unwinds the partial mappings by calling __do_unmap() with __unmap_iommu(): drivers/gpu/drm/msm/msm_iommu.c:__do_map() { ... if (ret) { __do_unmap(pgsize_bitmap, iova, addr - iova, arg, unmap); return -EINVAL; } ... } Because __unmap_iommu() passes NULL for the iotlb_gather parameter to domain->ops->unmap_pages() and __do_unmap() does not flush the IOTLB, stale translations for the rolled-back pages can remain cached in the IOTLB after msm_iommu_map() returns an error. In comparison, msm_iommu_pagetable_map() in the same file explicitly flushes the IOTLB on error: drivers/gpu/drm/msm/msm_iommu.c:msm_iommu_pagetable_map() { ... if (ret) { /* * If the map failed mid-way, it will have triggered an * unmap, so we need to flush the TLB: */ iommu_flush_iotlb_all(to_msm_iommu(pagetable->parent)->domain); } ... } Also, by replacing iommu_map_sgtable() with direct calls to domain->ops->map_pages() via __map_iommu(), msm_iommu_map() no longer invokes domain->ops->iotlb_sync_map(). On platforms using drivers/iommu/msm_iommu.c (such as APQ8064), msm_iommu_ops defines .iotlb_sync_map = msm_iommu_sync_map to flush the IOTLB after mapping pages. Without calling iotlb_sync_map, will those platforms miss required IOTLB synchronization on map? > > static int msm_iommu_unmap(struct msm_mmu *mmu, uint64_t iova, size_t len) > { > - struct msm_iommu *iommu = to_msm_iommu(mmu); > + struct iommu_domain *domain = to_msm_iommu(mmu)->domain; > + int ret; > > if (iova & BIT_ULL(48)) > iova |= GENMASK_ULL(63, 49); > > - iommu_unmap(iommu->domain, iova, len); > + ret = __do_unmap(domain->pgsize_bitmap, iova, len, domain, > __unmap_iommu); > > - return 0; > + iommu_flush_iotlb_all(domain); > + > + return ret; > } [Severity: Critical] Can replacing iommu_unmap() with __do_unmap() and iommu_flush_iotlb_all() skip leaf IOTLB invalidations on SoCs using qcom_iommu? Here, msm_iommu_unmap() calls __do_unmap() with __unmap_iommu(), which passes a NULL iotlb_gather pointer to domain->ops->unmap_pages(). In __arm_lpae_unmap() in drivers/iommu/io-pgtable-arm.c, per-page leaf TLB invalidations are only issued when gather is non-NULL: drivers/iommu/io-pgtable-arm.c:__arm_lpae_unmap() { ... 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); ... } When msm_iommu_unmap() subsequently calls iommu_flush_iotlb_all(domain), qcom_iommu_flush_iotlb_all() in drivers/iommu/arm/arm-smmu/qcom_iommu.c only issues a TLBSYNC without issuing a context-wide TLBIASID invalidation: drivers/iommu/arm/arm-smmu/qcom_iommu.c:qcom_iommu_flush_iotlb_all() { struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain); struct io_pgtable *pgtable = container_of(qcom_domain->pgtbl_ops, struct io_pgtable, ops); if (!qcom_domain->pgtbl_ops) return; pm_runtime_get_sync(qcom_domain->iommu->dev); qcom_iommu_tlb_sync(pgtable->cookie); pm_runtime_put_sync(qcom_domain->iommu->dev); } Because gather is NULL during unmap_pages() (skipping qcom_iommu_tlb_add_page() and its ARM_SMMU_CB_S1_TLBIVAL writes) and qcom_iommu_flush_iotlb_all() only syncs prior invalidations, wouldn't leaf IOTLB entries remain uninvalidated after unmapping buffers? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=4
