48 lines
1.9 KiB
Diff
48 lines
1.9 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Thu, 4 Aug 2022 15:28:32 +0200
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Subject: [PATCH] KVM: x86: do not report preemption if the steal time cache is
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stale
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commit c3c28d24d910a746b02f496d190e0e8c6560224b upstream.
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Commit 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time
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/ preempted status", 2021-11-11) open coded the previous call to
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kvm_map_gfn, but in doing so it dropped the comparison between the cached
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guest physical address and the one in the MSR. This cause an incorrect
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cache hit if the guest modifies the steal time address while the memslots
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remain the same. This can happen with kexec, in which case the preempted
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bit is written at the address used by the old kernel instead of
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the old one.
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Cc: David Woodhouse <dwmw@amazon.co.uk>
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Cc: stable@vger.kernel.org
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Fixes: 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempted status")
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kvm/x86.c | 2 ++
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1 file changed, 2 insertions(+)
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index b46677baf396..48aaff0ce3b9 100644
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -4370,6 +4370,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
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struct kvm_steal_time __user *st;
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struct kvm_memslots *slots;
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static const u8 preempted = KVM_VCPU_PREEMPTED;
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+ gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS;
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if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
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return;
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@@ -4384,6 +4385,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
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slots = kvm_memslots(vcpu->kvm);
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if (unlikely(slots->generation != ghc->generation ||
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+ gpa != ghc->gpa ||
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kvm_is_error_hva(ghc->hva) || !ghc->memslot))
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return;
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