KVM: nVMX: Truncate writes to vmcs.SYSENTER_EIP/ESP for 32-bit vCPU (2408500d) · Commits · 戴 / test

Explicitly truncate the data written to vmcs.SYSENTER_EIP/ESP on WRMSR if the virtual CPU doesn't support 64-bit mode. The SYSENTER address fields in the VMCS are natural width, i.e. bits 63:32 are dropped if the CPU doesn't support Intel 64 architectures. This behavior is visible to the guest after a VM-Exit/VM-Exit roundtrip, e.g. if the guest sets bits 63:32 in the actual MSR. Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Message-Id: <20200428231025.12766-2-sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

+16 −2

Original line number	Diff line number	Diff line
		@@ -1943,6 +1943,16 @@ static int vmx_get_msr(struct kvm_vcpu vcpu, struct msr_data msr_info)
		return 0;
		}

		static u64 nested_vmx_truncate_sysenter_addr(struct kvm_vcpu *vcpu,
		u64 data)
		{
		#ifdef CONFIG_X86_64
		if (!guest_cpuid_has(vcpu, X86_FEATURE_LM))
		return (u32)data;
		#endif
		return (unsigned long)data;
		}

		/*
		* Writes msr value into the appropriate "register".
		* Returns 0 on success, non-0 otherwise.
		@@ -1980,13 +1990,17 @@ static int vmx_set_msr(struct kvm_vcpu vcpu, struct msr_data msr_info)
		vmcs_write32(GUEST_SYSENTER_CS, data);
		break;
		case MSR_IA32_SYSENTER_EIP:
		if (is_guest_mode(vcpu))
		if (is_guest_mode(vcpu)) {
		data = nested_vmx_truncate_sysenter_addr(vcpu, data);
		get_vmcs12(vcpu)->guest_sysenter_eip = data;
		}
		vmcs_writel(GUEST_SYSENTER_EIP, data);
		break;
		case MSR_IA32_SYSENTER_ESP:
		if (is_guest_mode(vcpu))
		if (is_guest_mode(vcpu)) {
		data = nested_vmx_truncate_sysenter_addr(vcpu, data);
		get_vmcs12(vcpu)->guest_sysenter_esp = data;
		}
		vmcs_writel(GUEST_SYSENTER_ESP, data);
		break;
		case MSR_IA32_DEBUGCTLMSR:

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