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Subject[PATCH 2/2] KVM: x86: Don't update vcpu->arch.pv_eoi.msr_val when a bogus value was written to MSR_KVM_PV_EOI_EN
Date
When kvm_gfn_to_hva_cache_init() call from kvm_lapic_set_pv_eoi() fails,
MSR write to MSR_KVM_PV_EOI_EN results in #GP so it is reasonable to
expect that the value we keep internally in KVM wasn't updated.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/lapic.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 3573b50d9036..4388d22df500 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2857,20 +2857,25 @@ int kvm_lapic_set_pv_eoi(struct kvm_vcpu *vcpu, u64 data, unsigned long len)
u64 addr = data & ~KVM_MSR_ENABLED;
struct gfn_to_hva_cache *ghc = &vcpu->arch.pv_eoi.data;
unsigned long new_len;
+ int ret;

if (!IS_ALIGNED(addr, 4))
return 1;

- vcpu->arch.pv_eoi.msr_val = data;
- if (!pv_eoi_enabled(vcpu))
- return 0;
+ if (data & KVM_MSR_ENABLED) {
+ if (addr == ghc->gpa && len <= ghc->len)
+ new_len = ghc->len;
+ else
+ new_len = len;

- if (addr == ghc->gpa && len <= ghc->len)
- new_len = ghc->len;
- else
- new_len = len;
+ ret = kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, addr, new_len);
+ if (ret)
+ return ret;
+ }
+
+ vcpu->arch.pv_eoi.msr_val = data;

- return kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, addr, new_len);
+ return 0;
}

int kvm_apic_accept_events(struct kvm_vcpu *vcpu)
--
2.31.1
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