From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
David Matlack <dmatlack@google.com>,
Yan Zhao <yan.y.zhao@intel.com>,
Mingwei Zhang <mizhang@google.com>,
Ben Gardon <bgardon@google.com>
Subject: [PATCH v3 1/8] KVM: x86/mmu: Bug the VM if KVM attempts to double count an NX huge page
Date: Fri, 5 Aug 2022 23:05:06 +0000 [thread overview]
Message-ID: <20220805230513.148869-2-seanjc@google.com> (raw)
In-Reply-To: <20220805230513.148869-1-seanjc@google.com>
WARN and kill the VM if KVM attempts to double count an NX huge page,
i.e. attempts to re-tag a shadow page with "NX huge page disallowed".
KVM does NX huge page accounting only when linking a new shadow page, and
it should be impossible for a new shadow page to be already accounted.
E.g. even in the TDP MMU case, where vCPUs can race to install a new
shadow page, only the "winner" will account the installed page.
Kill the VM instead of continuing on as either KVM has an egregious bug,
e.g. didn't zero-initialize the data, or there's host data corruption, in
which carrying on is dangerous, e.g. could cause silent data corruption
in the guest.
Reported-by: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/mmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3e1317325e1f..36b898dbde91 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -804,7 +804,7 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
- if (sp->lpage_disallowed)
+ if (KVM_BUG_ON(sp->lpage_disallowed, kvm))
return;
++kvm->stat.nx_lpage_splits;
--
2.37.1.559.g78731f0fdb-goog
next prev parent reply other threads:[~2022-08-05 23:05 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-05 23:05 [PATCH v3 0/8] KVM: x86: Apply NX mitigation more precisely Sean Christopherson
2022-08-05 23:05 ` Sean Christopherson [this message]
2022-08-14 0:53 ` [PATCH v3 1/8] KVM: x86/mmu: Bug the VM if KVM attempts to double count an NX huge page Mingwei Zhang
2022-08-05 23:05 ` [PATCH v3 2/8] KVM: x86/mmu: Tag disallowed NX huge pages even if they're not tracked Sean Christopherson
2022-08-14 0:53 ` Mingwei Zhang
2022-08-05 23:05 ` [PATCH v3 3/8] KVM: x86/mmu: Rename NX huge pages fields/functions for consistency Sean Christopherson
2022-08-14 1:12 ` Mingwei Zhang
2022-08-15 21:54 ` Sean Christopherson
2022-08-16 21:09 ` Mingwei Zhang
2022-08-17 16:13 ` Sean Christopherson
2022-08-18 22:13 ` Mingwei Zhang
2022-08-18 23:45 ` Sean Christopherson
2022-08-19 18:30 ` Mingwei Zhang
2022-08-20 1:04 ` Mingwei Zhang
2022-08-05 23:05 ` [PATCH v3 4/8] KVM: x86/mmu: Properly account NX huge page workaround for nonpaging MMUs Sean Christopherson
2022-08-16 21:25 ` Mingwei Zhang
2022-08-05 23:05 ` [PATCH v3 5/8] KVM: x86/mmu: Set disallowed_nx_huge_page in TDP MMU before setting SPTE Sean Christopherson
2022-08-09 3:26 ` Yan Zhao
2022-08-09 12:49 ` Paolo Bonzini
2022-08-09 14:44 ` Sean Christopherson
2022-08-09 14:48 ` Paolo Bonzini
2022-08-09 15:05 ` Sean Christopherson
2022-08-05 23:05 ` [PATCH v3 6/8] KVM: x86/mmu: Track the number of TDP MMU pages, but not the actual pages Sean Christopherson
2022-08-05 23:05 ` [PATCH v3 7/8] KVM: x86/mmu: Add helper to convert SPTE value to its shadow page Sean Christopherson
2022-08-05 23:05 ` [PATCH v3 8/8] KVM: x86/mmu: explicitly check nx_hugepage in disallowed_hugepage_adjust() Sean Christopherson
2022-08-09 12:57 ` Paolo Bonzini
2022-08-09 14:49 ` Sean Christopherson
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