KVM: VMX: Add instruction rdtscp support for guest

Before enabling, execution of "rdtscp" in guest would result in #UD.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 57 insertions, 3 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 75e8931e96c7..74a66f0c00b4 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -151,6 +151,8 @@ struct vcpu_vmx {
         ktime_t entry_time;
         s64 vnmi_blocked_time;
         u32 exit_reason;
+
+        bool rdtscp_enabled;
 };
 
 static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
@@ -225,7 +227,7 @@ static const u32 vmx_msr_index[] = {
 #ifdef CONFIG_X86_64
         MSR_SYSCALL_MASK, MSR_LSTAR, MSR_CSTAR,
 #endif
-        MSR_EFER, MSR_K6_STAR,
+        MSR_EFER, MSR_TSC_AUX, MSR_K6_STAR,
 };
 #define NR_VMX_MSR ARRAY_SIZE(vmx_msr_index)
 
@@ -362,6 +364,12 @@ static inline int cpu_has_vmx_vpid(void)
                 SECONDARY_EXEC_ENABLE_VPID;
 }
 
+static inline int cpu_has_vmx_rdtscp(void)
+{
+        return vmcs_config.cpu_based_2nd_exec_ctrl &
+                SECONDARY_EXEC_RDTSCP;
+}
+
 static inline int cpu_has_virtual_nmis(void)
 {
         return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS;
@@ -893,6 +901,11 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
         vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
 }
 
+static bool vmx_rdtscp_supported(void)
+{
+        return cpu_has_vmx_rdtscp();
+}
+
 /*
  * Swap MSR entry in host/guest MSR entry array.
  */
@@ -928,6 +941,9 @@ static void setup_msrs(struct vcpu_vmx *vmx)
                 index = __find_msr_index(vmx, MSR_CSTAR);
                 if (index >= 0)
                         move_msr_up(vmx, index, save_nmsrs++);
+                index = __find_msr_index(vmx, MSR_TSC_AUX);
+                if (index >= 0 && vmx->rdtscp_enabled)
+                        move_msr_up(vmx, index, save_nmsrs++);
                 /*
                  * MSR_K6_STAR is only needed on long mode guests, and only
                  * if efer.sce is enabled.
@@ -1017,6 +1033,10 @@ 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_TSC_AUX:
+                if (!to_vmx(vcpu)->rdtscp_enabled)
+                        return 1;
+                /* Otherwise falls through */
         default:
                 vmx_load_host_state(to_vmx(vcpu));
                 msr = find_msr_entry(to_vmx(vcpu), msr_index);
@@ -1080,7 +1100,15 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
                         vcpu->arch.pat = data;
                         break;
                 }
-                /* Otherwise falls through to kvm_set_msr_common */
+                ret = kvm_set_msr_common(vcpu, msr_index, data);
+                break;
+        case MSR_TSC_AUX:
+                if (!vmx->rdtscp_enabled)
+                        return 1;
+                /* Check reserved bit, higher 32 bits should be zero */
+                if ((data >> 32) != 0)
+                        return 1;
+                /* Otherwise falls through */
         default:
                 msr = find_msr_entry(vmx, msr_index);
                 if (msr) {
@@ -1260,7 +1288,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
                         SECONDARY_EXEC_ENABLE_VPID |
                         SECONDARY_EXEC_ENABLE_EPT |
                         SECONDARY_EXEC_UNRESTRICTED_GUEST |
-                        SECONDARY_EXEC_PAUSE_LOOP_EXITING;
+                        SECONDARY_EXEC_PAUSE_LOOP_EXITING |
+                        SECONDARY_EXEC_RDTSCP;
                 if (adjust_vmx_controls(min2, opt2,
                                         MSR_IA32_VMX_PROCBASED_CTLS2,
                                         &_cpu_based_2nd_exec_control) < 0)
@@ -3988,8 +4017,31 @@ static bool vmx_gb_page_enable(void)
         return false;
 }
 
+static inline u32 bit(int bitno)
+{
+        return 1 << (bitno & 31);
+}
+
 static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 {
+        struct kvm_cpuid_entry2 *best;
+        struct vcpu_vmx *vmx = to_vmx(vcpu);
+        u32 exec_control;
+
+        vmx->rdtscp_enabled = false;
+        if (vmx_rdtscp_supported()) {
+                exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
+                if (exec_control & SECONDARY_EXEC_RDTSCP) {
+                        best = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
+                        if (best && (best->edx & bit(X86_FEATURE_RDTSCP)))
+                                vmx->rdtscp_enabled = true;
+                        else {
+                                exec_control &= ~SECONDARY_EXEC_RDTSCP;
+                                vmcs_write32(SECONDARY_VM_EXEC_CONTROL,
+                                                exec_control);
+                        }
+                }
+        }
 }
 
 static struct kvm_x86_ops vmx_x86_ops = {
@@ -4058,6 +4110,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
         .gb_page_enable = vmx_gb_page_enable,
 
         .cpuid_update = vmx_cpuid_update,
+
+        .rdtscp_supported = vmx_rdtscp_supported,
 };
 
 static int __init vmx_init(void)