KVM: x86 emulator: emulate CLTS internally

Avoid using ctxt->vcpu; we can do everything with ->get_cr() and ->set_cr().

A side effect is that we no longer activate the fpu on emulated CLTS; but that
should be very rare.
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -691,7 +691,6 @@ int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size, unsigned short port);
 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu);
 int kvm_emulate_halt(struct kvm_vcpu *vcpu);
 int emulate_invlpg(struct kvm_vcpu *vcpu, gva_t address);
-int emulate_clts(struct kvm_vcpu *vcpu);
 int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu);
 
 void kvm_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg);

arch/x86/kvm/emulate.c

@@ -2579,6 +2579,16 @@ static int em_invlpg(struct x86_emulate_ctxt *ctxt)
 	return X86EMUL_CONTINUE;
 }
 
+static int em_clts(struct x86_emulate_ctxt *ctxt)
+{
+	ulong cr0;
+
+	cr0 = ctxt->ops->get_cr(ctxt, 0);
+	cr0 &= ~X86_CR0_TS;
+	ctxt->ops->set_cr(ctxt, 0, cr0);
+	return X86EMUL_CONTINUE;
+}
+
 static bool valid_cr(int nr)
 {
 	switch (nr) {
@@ -4079,7 +4089,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 		rc = emulate_syscall(ctxt, ops);
 		break;
 	case 0x06:
-		emulate_clts(ctxt->vcpu);
+		rc = em_clts(ctxt);
 		break;
 	case 0x09:		/* wbinvd */
 		kvm_emulate_wbinvd(ctxt->vcpu);

arch/x86/kvm/x86.c

@@ -4153,13 +4153,6 @@ int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_wbinvd);
 
-int emulate_clts(struct kvm_vcpu *vcpu)
-{
-	kvm_x86_ops->set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~X86_CR0_TS));
-	kvm_x86_ops->fpu_activate(vcpu);
-	return X86EMUL_CONTINUE;
-}
-
 int emulator_get_dr(struct x86_emulate_ctxt *ctxt, int dr, unsigned long *dest)
 {
 	return _kvm_get_dr(emul_to_vcpu(ctxt), dr, dest);