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bh=Pju20CFh13puHUYFtOtzpLfsAN18NYvnMP/ZNBnwsKA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792580835; v=1; x=1793185635; b=IaPriw5BfVW9gEFnfu3PD1FlyMHM7/f5hFkSqPNok+4ccVfzjeGnnljf3cWCQ42NgoyUsyAt gp/yB1hle05hRGXFYpea6yXauJn80ffXE8lc7gC8wmumH/FnLLfjqAerP/OeDCHm7n/ZN7+ZNQV rcOnP8dbHEujL7l3+4lYlZ/U= X-Envelope-To: linux-arm-kernel@lists.infradead.org Received: by smtp.migadu.com with ESMTPS id 2cc7fc73b5d6669d; Wed, 21 Oct 2026 11:07:15 +0000 X-Mizu-Trace-ID: 2cc7fc73b5d6669d X-Migadu-Flow: FLOW_OUT From: Fuad Tabba To: Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: Joey Gouly , Suzuki K Poulose , Zenghui Yu , Steffen Eiden , Catalin Marinas , Will Deacon , Mark Rutland , Steven Price , Yang Shi , David Hildenbrand , Lorenzo Stoakes , Fuad Tabba , linux-kernel@vger.kernel.org Subject: [PATCH v2 3/4] KVM: arm64: Sanitise MTE tags when a permission fault installs a mapping Date: Wed, 21 Oct 2026 12:06:59 +0100 Message-ID: <20261021110700.493315-4-fuad.tabba@linux.dev> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261021110700.493315-1-fuad.tabba@linux.dev> References: <20261021110700.493315-1-fuad.tabba@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261021_120719_161505_63C4551C X-CRM114-Status: GOOD ( 15.25 ) X-Spam-Score: -0.2 (/) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 The stage-2 fault path sanitises MTE tags only on translation faults, as a permission fault normally just relaxes an existing leaf. However, when the page is backed by a THP, a permission fault at page granule installs a block whose other pages may never have been mapped or sanitised. Once dirty logging is off, a guest write to a page mapped read-only during logging installs the block, and the guest can read the tags those pages' previous owners left. Sanitise whenever the fault path calls kvm_pgtable_stage2_map() rather than relaxing permissions. If the VMM replaces the VMA after the guest takes a permission fault but before vma_lookup(), that path would map and sanitise memory from the new VMA without checking it. Run the VM_MTE_ALLOWED check in kvm_s2_fault_compute_prot() on permission faults too. Fixes: ea7fc1bb1cd1b ("KVM: arm64: Introduce MTE VM feature") Reviewed-by: Lorenzo Stoakes (ARM) Cc: stable@vger.kernel.org Signed-off-by: Fuad Tabba --- arch/arm64/kvm/mmu.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index a551b6bb13c21..6e10aa9913d71 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -2004,7 +2004,7 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd, if (s2fd->nested) *prot = adjust_nested_exec_perms(kvm, s2fd->nested, *prot); - if (!kvm_s2_fault_is_perm(s2fd) && !s2vi->map_non_cacheable && kvm_has_mte(kvm)) { + if (!s2vi->map_non_cacheable && kvm_has_mte(kvm)) { /* Check the VMM hasn't introduced a new disallowed VMA */ if (!s2vi->mte_allowed) return -EFAULT; @@ -2059,9 +2059,6 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, } } - if (!perm_fault_granule && !s2vi->map_non_cacheable && kvm_has_mte(kvm)) - sanitise_mte_tags(kvm, pfn, mapping_size); - /* * Under the premise of getting a FSC_PERM fault, we just need to relax * permissions only if mapping_size equals perm_fault_granule. Otherwise, @@ -2076,6 +2073,9 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, ret = KVM_PGT_FN(kvm_pgtable_stage2_relax_perms)(pgt, gfn_to_gpa(gfn), prot, flags); } else { + if (!s2vi->map_non_cacheable && kvm_has_mte(kvm)) + sanitise_mte_tags(kvm, pfn, mapping_size); + ret = KVM_PGT_FN(kvm_pgtable_stage2_map)(pgt, gfn_to_gpa(gfn), mapping_size, __pfn_to_phys(pfn), prot, memcache, flags); -- 2.47.3