From 2408500dfc8f275f9057586b81466989f0fafc59 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 28 Apr 2020 16:10:24 -0700 Subject: [PATCH] KVM: nVMX: Truncate writes to vmcs.SYSENTER_EIP/ESP for 32-bit vCPU 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 Message-Id: <20200428231025.12766-2-sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/vmx.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 9ce182d..fc2b660 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -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: -- 2.7.4