KVM: nVMX: Clean up handling of VMX-related MSRs

This simplifies the code and also stops issuing warning about writing to
unhandled MSRs when VMX is disabled or the Feature Control MSR is
locked - we do handle them all according to the spec.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 24 insertions, 56 deletions

diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h
index 37813b5ddc37..2e4a42d31cfe 100644
--- a/arch/x86/include/uapi/asm/msr-index.h
+++ b/arch/x86/include/uapi/asm/msr-index.h
@@ -527,6 +527,7 @@
 #define MSR_IA32_VMX_TRUE_PROCBASED_CTLS 0x0000048e
 #define MSR_IA32_VMX_TRUE_EXIT_CTLS      0x0000048f
 #define MSR_IA32_VMX_TRUE_ENTRY_CTLS     0x00000490
+#define MSR_IA32_VMX_VMFUNC             0x00000491
 
 /* VMX_BASIC bits and bitmasks */
 #define VMX_BASIC_VMCS_SIZE_SHIFT       32
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e539c45eb669..fc4a255d5426 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2361,32 +2361,10 @@ static inline u64 vmx_control_msr(u32 low, u32 high)
         return low | ((u64)high << 32);
 }
 
-/*
- * If we allow our guest to use VMX instructions (i.e., nested VMX), we should
- * also let it use VMX-specific MSRs.
- * vmx_get_vmx_msr() and vmx_set_vmx_msr() return 1 when we handled a
- * VMX-specific MSR, or 0 when we haven't (and the caller should handle it
- * like all other MSRs).
- */
+/* Returns 0 on success, non-0 otherwise. */
 static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
 {
-        if (!nested_vmx_allowed(vcpu) && msr_index >= MSR_IA32_VMX_BASIC &&
-                     msr_index <= MSR_IA32_VMX_TRUE_ENTRY_CTLS) {
-                /*
-                 * According to the spec, processors which do not support VMX
-                 * should throw a #GP(0) when VMX capability MSRs are read.
-                 */
-                kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
-                return 1;
-        }
-
         switch (msr_index) {
-        case MSR_IA32_FEATURE_CONTROL:
-                if (nested_vmx_allowed(vcpu)) {
-                        *pdata = to_vmx(vcpu)->nested.msr_ia32_feature_control;
-                        break;
-                }
-                return 0;
         case MSR_IA32_VMX_BASIC:
                 /*
                  * This MSR reports some information about VMX support. We
@@ -2453,38 +2431,9 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
                 *pdata = nested_vmx_ept_caps;
                 break;
         default:
-                return 0;
-        }
-
-        return 1;
-}
-
-static void vmx_leave_nested(struct kvm_vcpu *vcpu);
-
-static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
-{
-        u32 msr_index = msr_info->index;
-        u64 data = msr_info->data;
-        bool host_initialized = msr_info->host_initiated;
-
-        if (!nested_vmx_allowed(vcpu))
-                return 0;
-
-        if (msr_index == MSR_IA32_FEATURE_CONTROL) {
-                if (!host_initialized &&
-                                to_vmx(vcpu)->nested.msr_ia32_feature_control
-                                & FEATURE_CONTROL_LOCKED)
-                        return 0;
-                to_vmx(vcpu)->nested.msr_ia32_feature_control = data;
-                if (host_initialized && data == 0)
-                        vmx_leave_nested(vcpu);
                 return 1;
         }
 
-        /*
-         * No need to treat VMX capability MSRs specially: If we don't handle
-         * them, handle_wrmsr will #GP(0), which is correct (they are readonly)
-         */
         return 0;
 }
 
@@ -2530,13 +2479,20 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
         case MSR_IA32_SYSENTER_ESP:
                 data = vmcs_readl(GUEST_SYSENTER_ESP);
                 break;
+        case MSR_IA32_FEATURE_CONTROL:
+                if (!nested_vmx_allowed(vcpu))
+                        return 1;
+                data = to_vmx(vcpu)->nested.msr_ia32_feature_control;
+                break;
+        case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
+                if (!nested_vmx_allowed(vcpu))
+                        return 1;
+                return vmx_get_vmx_msr(vcpu, msr_index, pdata);
         case MSR_TSC_AUX:
                 if (!to_vmx(vcpu)->rdtscp_enabled)
                         return 1;
                 /* Otherwise falls through */
         default:
-                if (vmx_get_vmx_msr(vcpu, msr_index, pdata))
-                        return 0;
                 msr = find_msr_entry(to_vmx(vcpu), msr_index);
                 if (msr) {
                         data = msr->data;
@@ -2549,6 +2505,8 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
         return 0;
 }
 
+static void vmx_leave_nested(struct kvm_vcpu *vcpu);
+
 /*
  * Writes msr value into into the appropriate "register".
  * Returns 0 on success, non-0 otherwise.
@@ -2603,6 +2561,17 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
         case MSR_IA32_TSC_ADJUST:
                 ret = kvm_set_msr_common(vcpu, msr_info);
                 break;
+        case MSR_IA32_FEATURE_CONTROL:
+                if (!nested_vmx_allowed(vcpu) ||
+                    (to_vmx(vcpu)->nested.msr_ia32_feature_control &
+                     FEATURE_CONTROL_LOCKED && !msr_info->host_initiated))
+                        return 1;
+                vmx->nested.msr_ia32_feature_control = data;
+                if (msr_info->host_initiated && data == 0)
+                        vmx_leave_nested(vcpu);
+                break;
+        case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC:
+                return 1; /* they are read-only */
         case MSR_TSC_AUX:
                 if (!vmx->rdtscp_enabled)
                         return 1;
@@ -2611,8 +2580,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                         return 1;
                 /* Otherwise falls through */
         default:
-                if (vmx_set_vmx_msr(vcpu, msr_info))
-                        break;
                 msr = find_msr_entry(vmx, msr_index);
                 if (msr) {
                         msr->data = data;