KVM: nVMX: Validate EFER values for VM_ENTRY/EXIT_LOAD_IA32_EFER
As we may emulate the loading of EFER on VM-entry and VM-exit, implement
the checks that VMX performs on the guest and host values on vmlaunch/
vmresume. Factor out kvm_valid_efer for this purpose which checks for
set reserved bits.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 599f98b..18635ae 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -809,6 +809,7 @@
}
void kvm_enable_efer_bits(u64);
+bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 11ea3cb..d7ef556 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7558,6 +7558,7 @@
struct vcpu_vmx *vmx = to_vmx(vcpu);
int cpu;
struct loaded_vmcs *vmcs02;
+ bool ia32e;
if (!nested_vmx_check_permission(vcpu) ||
!nested_vmx_check_vmcs12(vcpu))
@@ -7649,6 +7650,45 @@
}
/*
+ * If the load IA32_EFER VM-entry control is 1, the following checks
+ * are performed on the field for the IA32_EFER MSR:
+ * - Bits reserved in the IA32_EFER MSR must be 0.
+ * - Bit 10 (corresponding to IA32_EFER.LMA) must equal the value of
+ * the IA-32e mode guest VM-exit control. It must also be identical
+ * to bit 8 (LME) if bit 31 in the CR0 field (corresponding to
+ * CR0.PG) is 1.
+ */
+ if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER) {
+ ia32e = (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) != 0;
+ if (!kvm_valid_efer(vcpu, vmcs12->guest_ia32_efer) ||
+ ia32e != !!(vmcs12->guest_ia32_efer & EFER_LMA) ||
+ ((vmcs12->guest_cr0 & X86_CR0_PG) &&
+ ia32e != !!(vmcs12->guest_ia32_efer & EFER_LME))) {
+ nested_vmx_entry_failure(vcpu, vmcs12,
+ EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
+ return 1;
+ }
+ }
+
+ /*
+ * If the load IA32_EFER VM-exit control is 1, bits reserved in the
+ * IA32_EFER MSR must be 0 in the field for that register. In addition,
+ * the values of the LMA and LME bits in the field must each be that of
+ * the host address-space size VM-exit control.
+ */
+ if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER) {
+ ia32e = (vmcs12->vm_exit_controls &
+ VM_EXIT_HOST_ADDR_SPACE_SIZE) != 0;
+ if (!kvm_valid_efer(vcpu, vmcs12->host_ia32_efer) ||
+ ia32e != !!(vmcs12->host_ia32_efer & EFER_LMA) ||
+ ia32e != !!(vmcs12->host_ia32_efer & EFER_LME)) {
+ nested_vmx_entry_failure(vcpu, vmcs12,
+ EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
+ return 1;
+ }
+ }
+
+ /*
* We're finally done with prerequisite checking, and can start with
* the nested entry.
*/
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e730a46..2a434bf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -845,23 +845,17 @@
MSR_IA32_MCG_CTL,
};
-static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
+bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
{
- u64 old_efer = vcpu->arch.efer;
-
if (efer & efer_reserved_bits)
- return 1;
-
- if (is_paging(vcpu)
- && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
- return 1;
+ return false;
if (efer & EFER_FFXSR) {
struct kvm_cpuid_entry2 *feat;
feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
- return 1;
+ return false;
}
if (efer & EFER_SVME) {
@@ -869,9 +863,24 @@
feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
- return 1;
+ return false;
}
+ return true;
+}
+EXPORT_SYMBOL_GPL(kvm_valid_efer);
+
+static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
+{
+ u64 old_efer = vcpu->arch.efer;
+
+ if (!kvm_valid_efer(vcpu, efer))
+ return 1;
+
+ if (is_paging(vcpu)
+ && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
+ return 1;
+
efer &= ~EFER_LMA;
efer |= vcpu->arch.efer & EFER_LMA;