From 25d2e3613d159782b66f497184ebdcf3ccb686ab Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Thu, 21 Oct 2010 13:35:04 -0200
Subject: [PATCH] kvm: save/restore x86-64 MSRs on x86-64 kernels

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
 target-i386/kvm.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index e2f7e2ef4..ae0a034ab 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -15,6 +15,7 @@
 #include <sys/types.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
+#include <sys/utsname.h>
 
 #include <linux/kvm.h>
 
@@ -53,6 +54,8 @@
 #define BUS_MCEERR_AO 5
 #endif
 
+static int lm_capable_kernel;
+
 #ifdef KVM_CAP_EXT_CPUID
 
 static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max)
@@ -523,6 +526,11 @@ int kvm_arch_init(KVMState *s, int smp_cpus)
 {
     int ret;
 
+    struct utsname utsname;
+
+    uname(&utsname);
+    lm_capable_kernel = strcmp(utsname.machine, "x86_64") == 0;
+
     /* create vm86 tss.  KVM uses vm86 mode to emulate 16-bit code
      * directly.  In order to use vm86 mode, a TSS is needed.  Since this
      * must be part of guest physical memory, we need to allocate it.  Older
@@ -810,11 +818,12 @@ static int kvm_put_msrs(CPUState *env, int level)
     if (kvm_has_msr_hsave_pa(env))
         kvm_msr_entry_set(&msrs[n++], MSR_VM_HSAVE_PA, env->vm_hsave);
 #ifdef TARGET_X86_64
-    /* FIXME if lm capable */
-    kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar);
-    kvm_msr_entry_set(&msrs[n++], MSR_KERNELGSBASE, env->kernelgsbase);
-    kvm_msr_entry_set(&msrs[n++], MSR_FMASK, env->fmask);
-    kvm_msr_entry_set(&msrs[n++], MSR_LSTAR, env->lstar);
+    if (lm_capable_kernel) {
+        kvm_msr_entry_set(&msrs[n++], MSR_CSTAR, env->cstar);
+        kvm_msr_entry_set(&msrs[n++], MSR_KERNELGSBASE, env->kernelgsbase);
+        kvm_msr_entry_set(&msrs[n++], MSR_FMASK, env->fmask);
+        kvm_msr_entry_set(&msrs[n++], MSR_LSTAR, env->lstar);
+    }
 #endif
     if (level == KVM_PUT_FULL_STATE) {
         /*
@@ -1046,11 +1055,12 @@ static int kvm_get_msrs(CPUState *env)
         msrs[n++].index = MSR_VM_HSAVE_PA;
     msrs[n++].index = MSR_IA32_TSC;
 #ifdef TARGET_X86_64
-    /* FIXME lm_capable_kernel */
-    msrs[n++].index = MSR_CSTAR;
-    msrs[n++].index = MSR_KERNELGSBASE;
-    msrs[n++].index = MSR_FMASK;
-    msrs[n++].index = MSR_LSTAR;
+    if (lm_capable_kernel) {
+        msrs[n++].index = MSR_CSTAR;
+        msrs[n++].index = MSR_KERNELGSBASE;
+        msrs[n++].index = MSR_FMASK;
+        msrs[n++].index = MSR_LSTAR;
+    }
 #endif
     msrs[n++].index = MSR_KVM_SYSTEM_TIME;
     msrs[n++].index = MSR_KVM_WALL_CLOCK;