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[54.240.197.234]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48de3f7f8b8sm9365477f8f.35.2026.10.14.02.37.45 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Oct 2026 02:37:45 -0700 (PDT) From: Fred Griffoul To: Paolo Bonzini , Sean Christopherson , Marc Zyngier , Oliver Upton , Catalin Marinas , Andrew Morton , David Hildenbrand , Alexander Viro , Christian Brauner , Jan Kara , Jason Gunthorpe , Kevin Tian , Joerg Roedel , Will Deacon , Robin Murphy , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Jonathan Corbet , Shuah Khan , Shuah Khan Cc: David Woodhouse , Ackerley Tng , "Aneesh Kumar K . V" , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Steffen Eiden , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org Subject: [RFC PATCH v2 08/11] iommufd/selftest: Add mock-domain IOVA queries Date: Wed, 14 Oct 2026 09:37:30 +0000 Message-ID: <20261014093733.90312-9-griffoul@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261014093733.90312-1-griffoul@gmail.com> References: <20261014093733.90312-1-griffoul@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Fred Griffoul A test of memory that can be taken back or replaced does not know in advance which frame a device reaches. IOMMU_TEST_OP_MD_CHECK_MAP only compares against a known buffer. Add MD_CHECK_MAPPED, which checks that a range is fully mapped or fully unmapped, and MD_IOVA_TO_PHYS, which returns the frame behind an IOVA, or 0 if it is unmapped. Both refuse an IOVA outside the domain's aperture. Both hold domains_rwsem for writing so that a userspace unmap cannot free a page-table level during the walk. Assisted-by: Claude:claude-opus-5-5 Signed-off-by: Fred Griffoul --- drivers/iommu/iommufd/iommufd_test.h | 16 ++++ drivers/iommu/iommufd/selftest.c | 109 +++++++++++++++++++++++++++ 2 files changed, 125 insertions(+) diff --git a/drivers/iommu/iommufd/iommufd_test.h b/drivers/iommu/iommufd/iommufd_test.h index 52b78cbcc920..28fd9c43edc4 100644 --- a/drivers/iommu/iommufd/iommufd_test.h +++ b/drivers/iommu/iommufd/iommufd_test.h @@ -31,6 +31,8 @@ enum { IOMMU_TEST_OP_PASID_CHECK_HWPT, IOMMU_TEST_OP_DMABUF_GET, IOMMU_TEST_OP_DMABUF_REVOKE, + IOMMU_TEST_OP_MD_CHECK_MAPPED, + IOMMU_TEST_OP_MD_IOVA_TO_PHYS, }; enum { @@ -193,6 +195,20 @@ struct iommu_test_cmd { __s32 dmabuf_fd; __u32 revoked; } dmabuf_revoke; + struct { + /* + * 1: every page in [iova, iova+length) must be mapped; + * 0: none of them may be. Mixed is an error. + */ + __u32 mapped; + __u32 __reserved; + __aligned_u64 iova; + __aligned_u64 length; + } check_mapped; + struct { + __aligned_u64 iova; + __aligned_u64 out_phys; /* 0 if unmapped */ + } iova_to_phys; }; __u32 last; }; diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c index af07c642a526..1f5cd2d00fda 100644 --- a/drivers/iommu/iommufd/selftest.c +++ b/drivers/iommu/iommufd/selftest.c @@ -2031,6 +2031,107 @@ static int iommufd_test_dmabuf_get(struct iommufd_ucmd *ucmd, return rc; } +/* + * True if [iova, iova + length) lies inside the domain's aperture. Outside + * it the page table returns an error code from iova_to_phys(), not 0. + */ +static bool mock_domain_covers(struct mock_iommu_domain *mock, + unsigned long iova, size_t length) +{ + struct iommu_domain_geometry *geo = &mock->domain.geometry; + unsigned long last; + + if (check_add_overflow(iova, length - 1, &last)) + return false; + return iova >= geo->aperture_start && last <= geo->aperture_end; +} + +/* + * iova_to_phys() walks the page table, so it must not run while an unmap + * frees a level of it. A userspace unmap holds the IOAS domains_rwsem for + * reading while it unmaps the domains, so holding it for writing keeps such + * unmaps away. A memory provider or dma-buf revoke unmaps under its pages + * mutex only, so tests must not run these queries while a revoke of the + * range is in progress. + */ +static struct rw_semaphore * +mock_domain_unmap_lock(struct iommufd_hw_pagetable *hwpt) +{ + return &to_hwpt_paging(hwpt)->ioas->iopt.domains_rwsem; +} + +/* + * Report the physical address the mock domain resolves @iova to, or 0 if + * it is unmapped. Lets a test check that two IOVAs share one frame, or that + * an IOVA moved to another frame, without knowing the frames in advance. + */ +static int iommufd_test_md_iova_to_phys(struct iommufd_ucmd *ucmd, + unsigned int mockpt_id, + unsigned long iova) +{ + struct iommu_test_cmd *cmd = ucmd->cmd; + struct iommufd_hw_pagetable *hwpt; + struct mock_iommu_domain *mock; + unsigned int page_size; + int rc; + + hwpt = get_md_pagetable(ucmd, mockpt_id, &mock); + if (IS_ERR(hwpt)) + return PTR_ERR(hwpt); + + page_size = 1 << __ffs(mock->domain.pgsize_bitmap); + if (iova % page_size || !mock_domain_covers(mock, iova, page_size)) { + rc = -EINVAL; + goto out_put; + } + down_write(mock_domain_unmap_lock(hwpt)); + cmd->iova_to_phys.out_phys = + mock->domain.ops->iova_to_phys(&mock->domain, iova); + up_write(mock_domain_unmap_lock(hwpt)); + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd)); +out_put: + iommufd_put_object(ucmd->ictx, &hwpt->obj); + return rc; +} + +static int iommufd_test_md_check_mapped(struct iommufd_ucmd *ucmd, + unsigned int mockpt_id, + unsigned long iova, size_t length, + bool mapped) +{ + struct iommufd_hw_pagetable *hwpt; + struct mock_iommu_domain *mock; + unsigned int page_size; + int rc = 0; + + hwpt = get_md_pagetable(ucmd, mockpt_id, &mock); + if (IS_ERR(hwpt)) + return PTR_ERR(hwpt); + + page_size = 1 << __ffs(mock->domain.pgsize_bitmap); + if (iova % page_size || length % page_size || !length || + !mock_domain_covers(mock, iova, length)) { + rc = -EINVAL; + goto out_put; + } + + down_write(mock_domain_unmap_lock(hwpt)); + for (; length; length -= page_size, iova += page_size) { + bool is_mapped = + mock->domain.ops->iova_to_phys(&mock->domain, iova) != 0; + + if (is_mapped != mapped) { + rc = -ENOENT; + break; + } + } + up_write(mock_domain_unmap_lock(hwpt)); + +out_put: + iommufd_put_object(ucmd->ictx, &hwpt->obj); + return rc; +} + static int iommufd_test_dmabuf_revoke(struct iommufd_ucmd *ucmd, int fd, bool revoked) { @@ -2143,6 +2244,14 @@ int iommufd_test(struct iommufd_ucmd *ucmd) return iommufd_test_dmabuf_revoke(ucmd, cmd->dmabuf_revoke.dmabuf_fd, cmd->dmabuf_revoke.revoked); + case IOMMU_TEST_OP_MD_CHECK_MAPPED: + return iommufd_test_md_check_mapped(ucmd, cmd->id, + cmd->check_mapped.iova, + cmd->check_mapped.length, + cmd->check_mapped.mapped); + case IOMMU_TEST_OP_MD_IOVA_TO_PHYS: + return iommufd_test_md_iova_to_phys(ucmd, cmd->id, + cmd->iova_to_phys.iova); default: return -EOPNOTSUPP; } -- 2.47.3