[PATCH] target-i386: check vcpu features before accessing MSR_TSC_AUX

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

This patch fix a bug that prevents VM rebooting on recent versions of
KVM (from commit 9dbe6cf).

kvm_get_msrs() is called to save guest MSR_TSC_AUX and other MSRs across
rebooting. It only checks whether KVM exposes MSR_TSC_AUX to userspace.
However, if vcpu does not support rdtscp (e.g. kvm64), current KVM will
fail the saving and thus all other MSRs following it will fail in
kvm_get_msrs(). As a result, from KVM commit 9dbe6cf that exposes
MSR_TSC_AUX, VM can not successfully reboot.

This patch fixes this bug by adding the missing rdtscp feature checks.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
 target-i386/kvm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 6dc9846..cc842c6 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -1414,7 +1414,8 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
     if (has_msr_hsave_pa) {
         kvm_msr_entry_set(&msrs[n++], MSR_VM_HSAVE_PA, env->vm_hsave);
     }
-    if (has_msr_tsc_aux) {
+    if (has_msr_tsc_aux &&
+        (env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_RDTSCP)) {
         kvm_msr_entry_set(&msrs[n++], MSR_TSC_AUX, env->tsc_aux);
     }
     if (has_msr_tsc_adjust) {
@@ -1793,7 +1794,8 @@ static int kvm_get_msrs(X86CPU *cpu)
     if (has_msr_hsave_pa) {
         msrs[n++].index = MSR_VM_HSAVE_PA;
     }
-    if (has_msr_tsc_aux) {
+    if (has_msr_tsc_aux &&
+        (env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_RDTSCP)) {
         msrs[n++].index = MSR_TSC_AUX;
     }
     if (has_msr_tsc_adjust) {
-- 
2.4.8

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