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 599f98b612d400870c7e3488f2bd339166f6ef2b..18635ae42a8e2eaa1e265c2efc74bb5a2c651348 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -809,6 +809,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
 }
 
 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 11ea3cbbb78c52a9ee2cffa89224c7ccb107a628..d7ef556862279e84027c0340573de8436b46d2d0 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7558,6 +7558,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
        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))
@@ -7648,6 +7649,45 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
                return 1;
        }
 
+       /*
+        * If the \93load IA32_EFER\94 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 e730a462ed05a375dfebf6896943a09705e0fa1e..2a434bf3918d684d877689fd7978d4c6e14f16ea 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -845,23 +845,17 @@ static const u32 emulated_msrs[] = {
        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 @@ static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
 
                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;