From e0b7de4fd18c47ebd47ec0dd1af6503d4071b943 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 26 Jul 2024 16:51:11 -0700 Subject: [PATCH] KVM: arm64: Disallow copying MTE to guest memory while KVM is dirty logging Disallow copying MTE tags to guest memory while KVM is dirty logging, as writing guest memory without marking the gfn as dirty in the memslot could result in userspace failing to migrate the updated page. Ideally (maybe?), KVM would simply mark the gfn as dirty, but there is no vCPU to work with, and presumably the only use case for copy MTE tags _to_ the guest is when restoring state on the target. Fixes: f0376edb1ddc ("KVM: arm64: Add ioctl to fetch/store tags in a guest") Signed-off-by: Sean Christopherson Reviewed-by: Steven Price Reviewed-by: Catalin Marinas Link: https://lore.kernel.org/r/20240726235234.228822-3-seanjc@google.com Signed-off-by: Marc Zyngier --- arch/arm64/kvm/guest.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index e1f0ff08836a..962f985977c2 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -1045,6 +1045,11 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, mutex_lock(&kvm->slots_lock); + if (write && atomic_read(&kvm->nr_memslots_dirty_logging)) { + ret = -EBUSY; + goto out; + } + while (length > 0) { kvm_pfn_t pfn = gfn_to_pfn_prot(kvm, gfn, write, NULL); void *maddr;