[Qemu-devel] [PULL 16/19] target-i386: block migration and savevm if invariant tsc is exposed

[Andreas Färber]

From: Marcelo Tosatti <address@hidden>

Invariant TSC documentation mentions that "invariant TSC will run at a
constant rate in all ACPI P-, C-. and T-states".

This is not the case if migration to a host with different TSC frequency
is allowed, or if savevm is performed. So block migration/savevm.

Signed-off-by: Marcelo Tosatti <address@hidden>
Reviewed-by: Eduardo Habkost <address@hidden>
Signed-off-by: Eduardo Habkost <address@hidden>
Reviewed-by: Juan Quintela <address@hidden>
[AF+mtosatti: Updated error message]
Signed-off-by: Andreas Färber <address@hidden>
---
 target-i386/cpu-qom.h |  2 +-
 target-i386/kvm.c     | 15 +++++++++++++++
 target-i386/machine.c |  2 +-
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/target-i386/cpu-qom.h b/target-i386/cpu-qom.h
index ff3a5de..71a1b97 100644
--- a/target-i386/cpu-qom.h
+++ b/target-i386/cpu-qom.h
@@ -121,7 +121,7 @@ static inline X86CPU *x86_env_get_cpu(CPUX86State *env)
 #define ENV_OFFSET offsetof(X86CPU, env)
 
 #ifndef CONFIG_USER_ONLY
-extern const struct VMStateDescription vmstate_x86_cpu;
+extern struct VMStateDescription vmstate_x86_cpu;
 #endif
 
 /**
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 4bf0ac9..097fe11 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -35,6 +35,8 @@
 #include "exec/ioport.h"
 #include <asm/hyperv.h>
 #include "hw/pci/pci.h"
+#include "migration/migration.h"
+#include "qapi/qmp/qerror.h"
 
 //#define DEBUG_KVM
 
@@ -448,6 +450,8 @@ static bool hyperv_enabled(X86CPU *cpu)
             cpu->hyperv_relaxed_timing);
 }
 
+static Error *invtsc_mig_blocker;
+
 #define KVM_MAX_CPUID_ENTRIES  100
 
 int kvm_arch_init_vcpu(CPUState *cs)
@@ -705,6 +709,17 @@ int kvm_arch_init_vcpu(CPUState *cs)
                                   !!(c->ecx & CPUID_EXT_SMX);
     }
 
+    c = cpuid_find_entry(&cpuid_data.cpuid, 0x80000007, 0);
+    if (c && (c->edx & 1<<8) && invtsc_mig_blocker == NULL) {
+        /* for migration */
+        error_setg(&invtsc_mig_blocker,
+                   "State blocked by non-migratable CPU device"
+                   " (invtsc flag)");
+        migrate_add_blocker(invtsc_mig_blocker);
+        /* for savevm */
+        vmstate_x86_cpu.unmigratable = 1;
+    }
+
     cpuid_data.cpuid.padding = 0;
     r = kvm_vcpu_ioctl(cs, KVM_SET_CPUID2, &cpuid_data);
     if (r) {
diff --git a/target-i386/machine.c b/target-i386/machine.c
index b8dcd2f..16d2f6a 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -603,7 +603,7 @@ static const VMStateDescription vmstate_msr_hyperv_time = {
     }
 };
 
-const VMStateDescription vmstate_x86_cpu = {
+VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
     .minimum_version_id = 3,
-- 
1.8.4.5