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KVM: arm64: Omit tag sync on stage-2 mappings of the zero page

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   f620d66af3 ("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: f620d66af3 ("arm64: mte: Do not flag the zero page as PG_mte_tagged")
Cc: stable@vger.kernel.org # 5.10.x
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ard Biesheuvel 2026-06-04 17:11:56 +02:00 committed by Will Deacon
parent 568def8e87
commit 2986a62574
1 changed files with 5 additions and 0 deletions
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5
arch/arm64/kvm/mmu.c
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@ -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)) {