[Qemu-devel] [PATCH] properly save kvm system time msr registers

[Glauber Costa <glommer@redhat.com>]

Currently, the msrs involved in setting up pvclock are not saved over
migration and/or save/restore. This patch puts their value in special
fields in our CPUState, and deal with them using vmstate.

kvm also has to account for it, by including them in the msr list
for the ioctls.

This is a backport from qemu-kvm.git

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
 target-i386/cpu.h     |    2 ++
 target-i386/kvm.c     |   13 +++++++++++++
 target-i386/machine.c |    3 +++
 3 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 5929d28..f589044 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -651,6 +651,8 @@ typedef struct CPUX86State {
     target_ulong fmask;
     target_ulong kernelgsbase;
 #endif
+    uint64_t system_time_msr;
+    uint64_t wall_clock_msr;
 
     uint64_t tsc;
 
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 0e69b57..8a6fa29 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -18,6 +18,7 @@
 #include <sys/utsname.h>
 
 #include <linux/kvm.h>
+#include <linux/kvm_para.h>
 
 #include "qemu-common.h"
 #include "sysemu.h"
@@ -500,6 +501,9 @@ static int kvm_put_msrs(CPUState *env)
         kvm_msr_entry_set(&msrs[n++], MSR_LSTAR, env->lstar);
     }
 #endif
+    kvm_msr_entry_set(&msrs[n++], MSR_KVM_SYSTEM_TIME,  env->system_time_msr);
+    kvm_msr_entry_set(&msrs[n++], MSR_KVM_WALL_CLOCK,  env->wall_clock_msr);
+
     msr_data.info.nmsrs = n;
 
     return kvm_vcpu_ioctl(env, KVM_SET_MSRS, &msr_data);
@@ -634,6 +638,9 @@ static int kvm_get_msrs(CPUState *env)
         msrs[n++].index = MSR_LSTAR;
     }
 #endif
+    msrs[n++].index = MSR_KVM_SYSTEM_TIME;
+    msrs[n++].index = MSR_KVM_WALL_CLOCK;
+
     msr_data.info.nmsrs = n;
     ret = kvm_vcpu_ioctl(env, KVM_GET_MSRS, &msr_data);
     if (ret < 0)
@@ -670,6 +677,12 @@ static int kvm_get_msrs(CPUState *env)
         case MSR_IA32_TSC:
             env->tsc = msrs[i].data;
             break;
+        case MSR_KVM_SYSTEM_TIME:
+            env->system_time_msr = msrs[i].data;
+            break;
+        case MSR_KVM_WALL_CLOCK:
+            env->wall_clock_msr = msrs[i].data;
+            break;
         }
     }
 
diff --git a/target-i386/machine.c b/target-i386/machine.c
index b13eff4..f6fe216 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -475,6 +475,9 @@ const VMStateDescription vmstate_cpu = {
         VMSTATE_UINT64_ARRAY_V(mce_banks, CPUState, MCE_BANKS_DEF *4, 10),
         /* rdtscp */
         VMSTATE_UINT64_V(tsc_aux, CPUState, 11),
+        /* KVM pvclock msr */
+        VMSTATE_UINT64_V(system_time_msr, CPUState, 11),
+        VMSTATE_UINT64_V(wall_clock_msr, CPUState, 11),
         VMSTATE_END_OF_LIST()
     }
 };
-- 
1.6.2.5