This is a note to let you know that I've just added the patch titled KVM: x86: revalidate steal time cache if MSR value changes to the 5.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-x86-revalidate-steal-time-cache-if-msr-value-changes.patch and it can be found in the queue-5.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 901d3765fa804ce42812f1d5b1f3de2dfbb26723 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini <pbonzini@xxxxxxxxxx> Date: Thu, 4 Aug 2022 15:28:32 +0200 Subject: KVM: x86: revalidate steal time cache if MSR value changes From: Paolo Bonzini <pbonzini@xxxxxxxxxx> commit 901d3765fa804ce42812f1d5b1f3de2dfbb26723 upstream. Commit 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempted status", 2021-11-11) open coded the previous call to kvm_map_gfn, but in doing so it dropped the comparison between the cached guest physical address and the one in the MSR. This cause an incorrect cache hit if the guest modifies the steal time address while the memslots remain the same. This can happen with kexec, in which case the steal time data is written at the address used by the old kernel instead of the old one. While at it, rename the variable from gfn to gpa since it is a plain physical address and not a right-shifted one. Reported-by: Dave Young <ruyang@xxxxxxxxxx> Reported-by: Xiaoying Yan <yiyan@xxxxxxxxxx> Analyzed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx> Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Fixes: 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempted status") Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kvm/x86.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3386,6 +3386,7 @@ static void record_steal_time(struct kvm struct gfn_to_hva_cache *ghc = &vcpu->arch.st.cache; struct kvm_steal_time __user *st; struct kvm_memslots *slots; + gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; u64 steal; u32 version; @@ -3403,13 +3404,12 @@ static void record_steal_time(struct kvm slots = kvm_memslots(vcpu->kvm); if (unlikely(slots->generation != ghc->generation || + gpa != ghc->gpa || kvm_is_error_hva(ghc->hva) || !ghc->memslot)) { - gfn_t gfn = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; - /* We rely on the fact that it fits in a single page. */ BUILD_BUG_ON((sizeof(*st) - 1) & KVM_STEAL_VALID_BITS); - if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gfn, sizeof(*st)) || + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa, sizeof(*st)) || kvm_is_error_hva(ghc->hva) || !ghc->memslot) return; } Patches currently in stable-queue which might be from pbonzini@xxxxxxxxxx are queue-5.19/kvm-x86-mmu-treat-nx-as-a-valid-spte-bit-for-npt.patch queue-5.19/kvm-x86-xen-initialize-xen-timer-only-once.patch queue-5.19/kvm-x86-tag-kvm_mmu_x86_module_init-with-__init.patch queue-5.19/kvm-x86-xen-stop-xen-timer-before-changing-irq.patch queue-5.19/kvm-put-the-extra-pfn-reference-when-reusing-a-pfn-in-the-gpc-cache.patch queue-5.19/kvm-drop-unused-gpa-param-from-gfn-pfn-cache-s-__release_gpc-helper.patch queue-5.19/kvm-nvmx-let-userspace-set-nvmx-msr-to-any-_host_-supported-value.patch queue-5.19/kvm-svm-disable-sev-es-support-if-mmio-caching-is-disable.patch queue-5.19/kvm-x86-mmu-fully-re-evaluate-mmio-caching-when-spte-masks-change.patch queue-5.19/kvm-x86-do-not-report-preemption-if-the-steal-time-cache-is-stale.patch queue-5.19/kvm-nvmx-inject-ud-if-vmxon-is-attempted-with-incompatible-cr0-cr4.patch queue-5.19/kvm-do-not-incorporate-page-offset-into-gfn-pfn-cache-user-address.patch queue-5.19/kvm-svm-don-t-bug-if-userspace-injects-an-interrupt-with-gif-0.patch queue-5.19/kvm-nvmx-snapshot-pre-vm-enter-bndcfgs-for-nested_run_pending-case.patch queue-5.19/kvm-x86-split-kvm_is_valid_cr4-and-export-only-the-non-vendor-bits.patch queue-5.19/kvm-fix-multiple-races-in-gfn-pfn-cache-refresh.patch queue-5.19/kvm-fully-serialize-gfn-pfn-cache-refresh-via-mutex.patch queue-5.19/kvm-nvmx-account-for-kvm-reserved-cr4-bits-in-consistency-checks.patch queue-5.19/kvm-nvmx-snapshot-pre-vm-enter-debugctl-for-nested_run_pending-case.patch queue-5.19/kvm-x86-revalidate-steal-time-cache-if-msr-value-changes.patch