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Thu, 04 Jun 2026 08:12:20 -0700 (PDT) Date: Thu, 4 Jun 2026 17:11:56 +0200 In-Reply-To: <20260604151151.150377-7-ardb+git@google.com> Mime-Version: 1.0 References: <20260604151151.150377-7-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=1172; i=ardb@kernel.org; h=from:subject; bh=dgwiIv5ocMLxRg+g7B0P7cuef9P7d1jooOl8YYuWFh8=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIUtx6j7/xBdu7ww3VF8umHhOrTxmv1X/ehmmq7us1DyOv i0p29bWUcrCIMbFICumyCIw+++7nacnStU6z5KFmcPKBDKEgYtTACaiuJuRoTl9/jm1B92rg88s qn5ctuPIxa2HebZOu21xL9pGok+oyYThv/c2me2fBNfc1z/w6F3xuZ0hWWpsYfkRcSH9aW1urJd 4WAE= X-Mailer: git-send-email 2.54.0.1032.g2f8565e1d1-goog Message-ID: <20260604151151.150377-11-ardb+git@google.com> Subject: [PATCH v2 4/5] KVM: arm64: Omit tag sync on stage-2 mappings of the zero page From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, Ard Biesheuvel , Kevin Brodsky , Mark Brown , Marc Zyngier , stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260604_161223_916563_A6BE0645 X-CRM114-Status: GOOD ( 13.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Ard Biesheuvel Commit f620d66af316 ("arm64: mte: Do not flag the zero page as PG_mte_tagged") removed the PG_mte_tagged flag from the zero page, but missed a KVM code path that may set this flag on the zero page when it is used in a stage-2 CoW mapping of anonymous memory. So disregard the zero page explicitly in sanitise_mte_tags(). Fixes: f620d66af316 ("arm64: mte: Do not flag the zero page as PG_mte_tagged") Cc: # 5.10.x Suggested-by: Catalin Marinas Signed-off-by: Ard Biesheuvel --- arch/arm64/kvm/mmu.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index d089c107d9b7..445d6cf035c9 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1479,6 +1479,11 @@ static void sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn, if (!kvm_has_mte(kvm)) return; + if (is_zero_pfn(pfn)) { + WARN_ON_ONCE(nr_pages != 1); + return; + } + if (folio_test_hugetlb(folio)) { /* Hugetlb has MTE flags set on head page only */ if (folio_try_hugetlb_mte_tagging(folio)) { -- 2.54.0.1032.g2f8565e1d1-goog