Re: [PATCH v3 08/15] KVM: WARN and reject guest-based uaccess if VM is dying
flat view
From: James Houghton <hidden>
Date: 2026-10-28 00:27:01
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kvm, lkml
On Tue, Oct 27, 2026 at 3:12 PM Sean Christopherson [off-list ref] wrote:
WARN and reject user accesses to guest memory if the associated VM is dying even if the current address space happens to be the correct address space. Accessing guest memory after the last reference to the VM has been put may be "fine" from a safety perspective, but it's still a KVM bug. Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: James Houghton <redacted>
quoted hunk ↗ jump to hunk
--- include/linux/kvm_host.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index f3f59bdf7e18..ba8ea62b7304 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h@@ -1355,7 +1355,8 @@ int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc, static __always_inline __must_check bool kvm_can_do_uaccess(struct kvm *kvm) { - return !WARN_ON_ONCE(current->mm != kvm->mm); + return !WARN_ON_ONCE(current->mm != kvm->mm || + !refcount_read(&kvm->users_count)); } #define BUILD_KVM_COPY_USER_WRAPPER(fn, to_user, from_user) \ --2.56.0.307.g5fe7bd680c-goog