KVM: x86 emulator: implement rdmsr and wrmsr

Allow real-mode emulation of rdmsr and wrmsr. This allows smp Windows to
boot, presumably for its sipi trampoline.

Signed-off-by: Avi Kivity <[e-mail]>

drivers/kvm/kvm.h

···
 unsigned long realmode_get_cr(struct kvm_vcpu *vcpu, int cr);
 void realmode_set_cr(struct kvm_vcpu *vcpu, int cr, unsigned long value,
 		     unsigned long *rflags);
+int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
+int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 
 struct x86_emulate_ctxt;
 

drivers/kvm/kvm_main.c

···
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-static int get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
+int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
 {
 	return kvm_arch_ops->get_msr(vcpu, msr_index, pdata);
 }
···
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-static int set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
+int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
 {
 	return kvm_arch_ops->set_msr(vcpu, msr_index, data);
 }
···
  */
 static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
 {
-	return set_msr(vcpu, index, *data);
+	return kvm_set_msr(vcpu, index, *data);
 }
 
 /*
···
 		break;
 	}
 	case KVM_GET_MSRS:
-		r = msr_io(vcpu, argp, get_msr, 1);
+		r = msr_io(vcpu, argp, kvm_get_msr, 1);
 		break;
 	case KVM_SET_MSRS:
 		r = msr_io(vcpu, argp, do_set_msr, 0);

drivers/kvm/x86_emulate.c

···
 	ModRM | ImplicitOps, ModRM, ModRM | ImplicitOps, ModRM, 0, 0, 0, 0,
 	0, 0, 0, 0, 0, 0, 0, 0,
 	/* 0x30 - 0x3F */
-	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	ImplicitOps, 0, ImplicitOps, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 	/* 0x40 - 0x47 */
 	DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem | ModRM | Mov,
 	DstReg | SrcMem | ModRM | Mov, DstReg | SrcMem | ModRM | Mov,
···
 	unsigned long modrm_ea;
 	int use_modrm_ea, index_reg = 0, base_reg = 0, scale, rip_relative = 0;
 	int no_wb = 0;
+	u64 msr_data;
 
 	/* Shadow copy of register state. Committed on successful emulation. */
 	unsigned long _regs[NR_VCPU_REGS];
···
 		if (modrm_mod != 3)
 			goto cannot_emulate;
 		realmode_set_cr(ctxt->vcpu, modrm_reg, modrm_val, &_eflags);
+		break;
+	case 0x30:
+		/* wrmsr */
+		msr_data = (u32)_regs[VCPU_REGS_RAX]
+			| ((u64)_regs[VCPU_REGS_RDX] << 32);
+		rc = kvm_set_msr(ctxt->vcpu, _regs[VCPU_REGS_RCX], msr_data);
+		if (rc) {
+			kvm_arch_ops->inject_gp(ctxt->vcpu, 0);
+			_eip = ctxt->vcpu->rip;
+		}
+		rc = X86EMUL_CONTINUE;
+		break;
+	case 0x32:
+		/* rdmsr */
+		rc = kvm_get_msr(ctxt->vcpu, _regs[VCPU_REGS_RCX], &msr_data);
+		if (rc) {
+			kvm_arch_ops->inject_gp(ctxt->vcpu, 0);
+			_eip = ctxt->vcpu->rip;
+		} else {
+			_regs[VCPU_REGS_RAX] = (u32)msr_data;
+			_regs[VCPU_REGS_RDX] = msr_data >> 32;
+		}
+		rc = X86EMUL_CONTINUE;
 		break;
 	case 0xc7:		/* Grp9 (cmpxchg8b) */
 		{