KVM: x86 emulator: implement RDTSC (opcode 0F 31)

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7f7fc646678a..ed192d220201 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2279,6 +2279,22 @@ static int em_imul_3op(struct x86_emulate_ctxt *ctxt)
         return em_imul(ctxt);
 }
 
+static int em_rdtsc(struct x86_emulate_ctxt *ctxt)
+{
+        unsigned cpl = ctxt->ops->cpl(ctxt->vcpu);
+        struct decode_cache *c = &ctxt->decode;
+        u64 tsc = 0;
+
+        if (cpl > 0 && (ctxt->ops->get_cr(4, ctxt->vcpu) & X86_CR4_TSD)) {
+                emulate_gp(ctxt, 0);
+                return X86EMUL_PROPAGATE_FAULT;
+        }
+        ctxt->ops->get_msr(ctxt->vcpu, MSR_IA32_TSC, &tsc);
+        c->regs[VCPU_REGS_RAX] = (u32)tsc;
+        c->regs[VCPU_REGS_RDX] = tsc >> 32;
+        return X86EMUL_CONTINUE;
+}
+
 #define D(_y) { .flags = (_y) }
 #define N    D(0)
 #define G(_f, _g) { .flags = ((_f) | Group), .u.group = (_g) }
@@ -2469,7 +2485,8 @@ static struct opcode twobyte_table[256] = {
         N, N, N, N,
         N, N, N, N, N, N, N, N,
         /* 0x30 - 0x3F */
-        D(ImplicitOps | Priv), N, D(ImplicitOps | Priv), N,
+        D(ImplicitOps | Priv), I(ImplicitOps, em_rdtsc),
+        D(ImplicitOps | Priv), N,
         D(ImplicitOps), D(ImplicitOps | Priv), N, N,
         N, N, N, N, N, N, N, N,
         /* 0x40 - 0x4F */