61 lines
2.5 KiB
Diff
61 lines
2.5 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: revalidate steal time cache if MSR value changes
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commit 901d3765fa804ce42812f1d5b1f3de2dfbb26723 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 steal
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time data is written at the address used by the old kernel instead of
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the old one.
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While at it, rename the variable from gfn to gpa since it is a plain
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physical address and not a right-shifted one.
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Reported-by: Dave Young <ruyang@redhat.com>
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Reported-by: Xiaoying Yan <yiyan@redhat.com>
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Analyzed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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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 | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index aec63cebe0b7..a99eec435652 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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@@ -3356,6 +3356,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
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struct gfn_to_hva_cache *ghc = &vcpu->arch.st.cache;
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struct kvm_steal_time __user *st;
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struct kvm_memslots *slots;
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+ gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS;
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u64 steal;
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u32 version;
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@@ -3373,13 +3374,12 @@ static void record_steal_time(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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- gfn_t gfn = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS;
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-
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/* We rely on the fact that it fits in a single page. */
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BUILD_BUG_ON((sizeof(*st) - 1) & KVM_STEAL_VALID_BITS);
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- if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gfn, sizeof(*st)) ||
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+ if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa, sizeof(*st)) ||
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kvm_is_error_hva(ghc->hva) || !ghc->memslot)
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return;
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}
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