From 9ffd986c6e4e59c11857cbc78e4217e9569f3725 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Thu, 19 Oct 2017 06:47:56 -0700 Subject: [PATCH] KVM: X86: #GP when guest attempts to write MCi_STATUS register w/o 0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Both Intel SDM and AMD APM mentioned that MCi_STATUS, when the register is implemented, this register can be cleared by explicitly writing 0s to this register. Writing 1s to this register will cause a general-protection exception. The mce is emulated in qemu, so just the guest attempts to write 1 to this register should cause a #GP, this patch does it. Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Jim Mattson Signed-off-by: Wanpeng Li Reviewed-by: Jim Mattson Signed-off-by: Radim Krčmář --- arch/x86/kvm/x86.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3b51c8659741..34c85aa2e2d1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2006,10 +2006,12 @@ static void kvmclock_sync_fn(struct work_struct *work) KVMCLOCK_SYNC_PERIOD); } -static int set_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 data) +static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info) { u64 mcg_cap = vcpu->arch.mcg_cap; unsigned bank_num = mcg_cap & 0xff; + u32 msr = msr_info->index; + u64 data = msr_info->data; switch (msr) { case MSR_IA32_MCG_STATUS: @@ -2034,6 +2036,9 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 data) if ((offset & 0x3) == 0 && data != 0 && (data | (1 << 10)) != ~(u64)0) return -1; + if (!msr_info->host_initiated && + (offset & 0x3) == 1 && data != 0) + return -1; vcpu->arch.mce_banks[offset] = data; break; } @@ -2283,7 +2288,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_IA32_MCG_CTL: case MSR_IA32_MCG_STATUS: case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1: - return set_msr_mce(vcpu, msr, data); + return set_msr_mce(vcpu, msr_info); case MSR_K7_PERFCTR0 ... MSR_K7_PERFCTR3: case MSR_P6_PERFCTR0 ... MSR_P6_PERFCTR1: -- 2.45.2