[Qemu-devel] [PATCH] i386: wire up MSR_IA32_MISC_ENABLE

[Avi Kivity]

It's needed for its default value - bit 0 specifies that "rep movs" is
good enough for memcpy, and Linux may use a slower memcpu if it is not set,
depending on cpu family/model.

Signed-off-by: Avi Kivity <address@hidden>
---
 target-i386/cpu.h       |    5 +++++
 target-i386/helper.c    |    1 +
 target-i386/kvm.c       |   15 +++++++++++++++
 target-i386/machine.c   |   21 +++++++++++++++++++++
 target-i386/op_helper.c |    6 ++++++
 5 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index ae36489..5416809 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -299,6 +299,10 @@
 
 #define MSR_IA32_PERF_STATUS            0x198
 
+#define MSR_IA32_MISC_ENABLE           0x1a0
+/* Indicates good rep/movs microcode on some processors: */
+#define MSR_IA32_MISC_ENABLE_DEFAULT    1
+
 #define MSR_MTRRphysBase(reg)          (0x200 + 2 * (reg))
 #define MSR_MTRRphysMask(reg)          (0x200 + 2 * (reg) + 1)
 
@@ -689,6 +693,7 @@ typedef struct CPUX86State {
     uint64_t tsc;
 
     uint64_t mcg_status;
+    uint64_t msr_ia32_misc_enable;
 
     /* exception/interrupt handling */
     int error_code;
diff --git a/target-i386/helper.c b/target-i386/helper.c
index 5df40d4..6c6a167 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -98,6 +98,7 @@ void cpu_reset(CPUX86State *env)
     env->mxcsr = 0x1f80;
 
     env->pat = 0x0007040600070406ULL;
+    env->msr_ia32_misc_enable = MSR_IA32_MISC_ENABLE_DEFAULT;
 
     memset(env->dr, 0, sizeof(env->dr));
     env->dr[6] = DR6_FIXED_1;
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index b6eef04..b3a650b 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -60,6 +60,7 @@
 static bool has_msr_star;
 static bool has_msr_hsave_pa;
 static bool has_msr_async_pf_en;
+static bool has_msr_misc_enable;
 static int lm_capable_kernel;
 
 static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max)
@@ -568,6 +569,10 @@ static int kvm_get_supported_msrs(KVMState *s)
                     has_msr_hsave_pa = true;
                     continue;
                 }
+                if (kvm_msr_list->indices[i] == MSR_IA32_MISC_ENABLE) {
+                    has_msr_misc_enable = true;
+                    continue;
+                }
             }
         }
 
@@ -881,6 +886,10 @@ static int kvm_put_msrs(CPUState *env, int level)
     if (has_msr_hsave_pa) {
         kvm_msr_entry_set(&msrs[n++], MSR_VM_HSAVE_PA, env->vm_hsave);
     }
+    if (has_msr_misc_enable) {
+        kvm_msr_entry_set(&msrs[n++], MSR_IA32_MISC_ENABLE,
+                          env->msr_ia32_misc_enable);
+    }
 #ifdef TARGET_X86_64
     if (lm_capable_kernel) {
         kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar);
@@ -1127,6 +1136,9 @@ static int kvm_get_msrs(CPUState *env)
     if (has_msr_hsave_pa) {
         msrs[n++].index = MSR_VM_HSAVE_PA;
     }
+    if (has_msr_misc_enable) {
+        msrs[n++].index = MSR_IA32_MISC_ENABLE;
+    }
 
     if (!env->tsc_valid) {
         msrs[n++].index = MSR_IA32_TSC;
@@ -1210,6 +1222,9 @@ static int kvm_get_msrs(CPUState *env)
         case MSR_MCG_CTL:
             env->mcg_ctl = msrs[i].data;
             break;
+        case MSR_IA32_MISC_ENABLE:
+            env->msr_ia32_misc_enable = msrs[i].data;
+            break;
         default:
             if (msrs[i].index >= MSR_MC0_CTL &&
                 msrs[i].index < MSR_MC0_CTL + (env->mcg_cap & 0xff) * 4) {
diff --git a/target-i386/machine.c b/target-i386/machine.c
index 9aca8e0..73c1ffe 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -310,6 +310,24 @@ static bool fpop_ip_dp_needed(void *opaque)
     }
 };
 
+static bool misc_enable_needed(void *opaque)
+{
+    CPUState *env = opaque;
+
+    return env->msr_ia32_misc_enable != MSR_IA32_MISC_ENABLE_DEFAULT;
+}
+
+static const VMStateDescription vmstate_msr_ia32_misc_enable = {
+    .name = "cpu/msr_ia32_misc_enable",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField []) {
+        VMSTATE_UINT64(msr_ia32_misc_enable, CPUState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription vmstate_cpu = {
     .name = "cpu",
     .version_id = CPU_SAVE_VERSION,
@@ -420,6 +438,9 @@ static bool fpop_ip_dp_needed(void *opaque)
         } , {
             .vmsd = &vmstate_fpop_ip_dp,
             .needed = fpop_ip_dp_needed,
+        }, {
+            .vmsd = &vmstate_msr_ia32_misc_enable,
+            .needed = misc_enable_needed,
         } , {
             /* empty */
         }
diff --git a/target-i386/op_helper.c b/target-i386/op_helper.c
index 3bb5a91..c89e4a4 100644
--- a/target-i386/op_helper.c
+++ b/target-i386/op_helper.c
@@ -3280,6 +3280,9 @@ void helper_wrmsr(void)
     case MSR_TSC_AUX:
         env->tsc_aux = val;
         break;
+    case MSR_IA32_MISC_ENABLE:
+        env->msr_ia32_misc_enable = val;
+        break;
     default:
         if ((uint32_t)ECX >= MSR_MC0_CTL
             && (uint32_t)ECX < MSR_MC0_CTL + (4 * env->mcg_cap & 0xff)) {
@@ -3413,6 +3416,9 @@ void helper_rdmsr(void)
     case MSR_MCG_STATUS:
         val = env->mcg_status;
         break;
+    case MSR_IA32_MISC_ENABLE:
+        val = env->msr_ia32_misc_enable;
+        break;
     default:
         if ((uint32_t)ECX >= MSR_MC0_CTL
             && (uint32_t)ECX < MSR_MC0_CTL + (4 * env->mcg_cap & 0xff)) {
-- 
1.7.6.3