From 7d786ee2a9fe41aec8e1abad9e5bb89f16de5752 Mon Sep 17 00:00:00 2001
From: Neel Natu <neel@FreeBSD.org>
Date: Thu, 30 Apr 2015 19:23:50 +0000
Subject: [PATCH] Advertise the MTRR feature via CPUID and emulate the minimal
 set of MTRR MSRs. This is required for booting Windows guests.

Reported by:	Leon Dang (ldang@nahannisys.com)
MFC after:	2 weeks
---
 sys/amd64/vmm/amd/svm_msr.c   | 23 ++++++++++++++++++++++-
 sys/amd64/vmm/intel/vmx_msr.c | 15 +++++++++++++++
 sys/amd64/vmm/x86.c           |  3 +--
 3 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/sys/amd64/vmm/amd/svm_msr.c b/sys/amd64/vmm/amd/svm_msr.c
index 100af4b34bd..dfc79c4348d 100644
--- a/sys/amd64/vmm/amd/svm_msr.c
+++ b/sys/amd64/vmm/amd/svm_msr.c
@@ -27,12 +27,18 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
-#include <sys/types.h>
+#include <sys/param.h>
 #include <sys/errno.h>
+#include <sys/systm.h>
+#include <sys/cpuset.h>
 
 #include <machine/cpufunc.h>
 #include <machine/specialreg.h>
+#include <machine/vmm.h>
 
+#include "svm.h"
+#include "vmcb.h"
+#include "svm_softc.h"
 #include "svm_msr.h"
 
 #ifndef MSR_AMDK8_IPM
@@ -105,6 +111,13 @@ svm_rdmsr(struct svm_softc *sc, int vcpu, u_int num, uint64_t *result,
 	int error = 0;
 
 	switch (num) {
+	case MSR_MTRRcap:
+	case MSR_MTRRdefType:
+	case MSR_MTRR4kBase ... MSR_MTRR4kBase + 8:
+	case MSR_MTRR16kBase ... MSR_MTRR16kBase + 1:
+	case MSR_MTRR64kBase:
+		*result = 0;
+		break;
 	case MSR_AMDK8_IPM:
 		*result = 0;
 		break;
@@ -122,6 +135,14 @@ svm_wrmsr(struct svm_softc *sc, int vcpu, u_int num, uint64_t val, bool *retu)
 	int error = 0;
 
 	switch (num) {
+	case MSR_MTRRcap:
+		vm_inject_gp(sc->vm, vcpu);
+		break;
+	case MSR_MTRRdefType:
+	case MSR_MTRR4kBase ... MSR_MTRR4kBase + 8:
+	case MSR_MTRR16kBase ... MSR_MTRR16kBase + 1:
+	case MSR_MTRR64kBase:
+		break;		/* Ignore writes */
 	case MSR_AMDK8_IPM:
 		/*
 		 * Ignore writes to the "Interrupt Pending Message" MSR.
diff --git a/sys/amd64/vmm/intel/vmx_msr.c b/sys/amd64/vmm/intel/vmx_msr.c
index e5177786e4a..d54304d3fef 100644
--- a/sys/amd64/vmm/intel/vmx_msr.c
+++ b/sys/amd64/vmm/intel/vmx_msr.c
@@ -396,6 +396,13 @@ vmx_rdmsr(struct vmx *vmx, int vcpuid, u_int num, uint64_t *val, bool *retu)
 	error = 0;
 
 	switch (num) {
+	case MSR_MTRRcap:
+	case MSR_MTRRdefType:
+	case MSR_MTRR4kBase ... MSR_MTRR4kBase + 8:
+	case MSR_MTRR16kBase ... MSR_MTRR16kBase + 1:
+	case MSR_MTRR64kBase:
+		*val = 0;
+		break;
 	case MSR_IA32_MISC_ENABLE:
 		*val = misc_enable;
 		break;
@@ -427,6 +434,14 @@ vmx_wrmsr(struct vmx *vmx, int vcpuid, u_int num, uint64_t val, bool *retu)
 	error = 0;
 
 	switch (num) {
+	case MSR_MTRRcap:
+		vm_inject_gp(vmx->vm, vcpuid);
+		break;
+	case MSR_MTRRdefType:
+	case MSR_MTRR4kBase ... MSR_MTRR4kBase + 8:
+	case MSR_MTRR16kBase ... MSR_MTRR16kBase + 1:
+	case MSR_MTRR64kBase:
+		break;		/* Ignore writes */
 	case MSR_IA32_MISC_ENABLE:
 		changed = val ^ misc_enable;
 		/*
diff --git a/sys/amd64/vmm/x86.c b/sys/amd64/vmm/x86.c
index c37d21c6e1b..1bd1b56c6ee 100644
--- a/sys/amd64/vmm/x86.c
+++ b/sys/amd64/vmm/x86.c
@@ -289,9 +289,8 @@ x86_emulate_cpuid(struct vm *vm, int vcpu_id,
 			
 			/*
 			 * Machine check handling is done in the host.
-			 * Hide MTRR capability.
 			 */
-			regs[3] &= ~(CPUID_MCA | CPUID_MCE | CPUID_MTRR);
+			regs[3] &= ~(CPUID_MCA | CPUID_MCE);
 
                         /*
                         * Hide the debug store capability.