From c911f0d4687947915f04024aa01803247fcf7f1a Mon Sep 17 00:00:00 2001 From: Peter Collingbourne Date: Thu, 3 Nov 2022 18:10:40 -0700 Subject: [PATCH] KVM: arm64: permit all VM_MTE_ALLOWED mappings with MTE enabled Certain VMMs such as crosvm have features (e.g. sandboxing) that depend on being able to map guest memory as MAP_SHARED. The current restriction on sharing MAP_SHARED pages with the guest is preventing the use of those features with MTE. Now that the races between tasks concurrently clearing tags on the same page have been fixed, remove this restriction. Note that this is a relaxation of the ABI. Signed-off-by: Peter Collingbourne Reviewed-by: Catalin Marinas Reviewed-by: Steven Price Reviewed-by: Cornelia Huck Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20221104011041.290951-8-pcc@google.com --- arch/arm64/kvm/mmu.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 9ff9a271cf01b..b9402d8b5a90c 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1110,14 +1110,6 @@ static void sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn, static bool kvm_vma_mte_allowed(struct vm_area_struct *vma) { - /* - * VM_SHARED mappings are not allowed with MTE to avoid races - * when updating the PG_mte_tagged page flag, see - * sanitise_mte_tags for more details. - */ - if (vma->vm_flags & VM_SHARED) - return false; - return vma->vm_flags & VM_MTE_ALLOWED; }