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authorLiang Li <liang.z.li@intel.com>2015-12-08 09:14:07 +0800
committerLiang Li <liang.z.li@intel.com>2015-12-08 09:16:17 +0800
commitb52baab237a0b45cb18b26f529e6490b42574209 (patch)
treee8bd69d1ccf45f46381617d27cfdd1966abde0b1 /qemu/target-i386
parentcc62f651747d5844cc12d33fb3620a7d05bae7dc (diff)
kvmclock: add a new function to update env->tsc.WW-2015-52
(Back port from upstream, commit id: 0fd7e098db30e302d27920487f0afec) The commit 317b0a6d8 fixed an issue which caused by the outdated env->tsc value, but the fix lead to 'cpu_synchronize_all_states()' called twice during live migration. The 'cpu_synchronize_all_states()' takes about 130us for a VM which has 4 vcpus, it's a bit expensive. Synchronize the whole CPU context just for updating env->tsc is too wasting, this patch use a new function to update the env->tsc. Comparing to 'cpu_synchronize_all_states()', it only takes about 20us. Change-Id: I7dc8371aa17b005d073249c3732d9a7424f20a25 Signed-off-by: Liang Li <liang.z.li@intel.com> Message-Id: <1446695464-27116-2-git-send-email-liang.z.li@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'qemu/target-i386')
-rw-r--r--qemu/target-i386/kvm.c45
-rw-r--r--qemu/target-i386/kvm_i386.h1
2 files changed, 46 insertions, 0 deletions
diff --git a/qemu/target-i386/kvm.c b/qemu/target-i386/kvm.c
index 066d03d99..721c580ed 100644
--- a/qemu/target-i386/kvm.c
+++ b/qemu/target-i386/kvm.c
@@ -96,6 +96,51 @@ bool kvm_allows_irq0_override(void)
return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();
}
+static int kvm_get_tsc(CPUState *cs)
+{
+ X86CPU *cpu = X86_CPU(cs);
+ CPUX86State *env = &cpu->env;
+ struct {
+ struct kvm_msrs info;
+ struct kvm_msr_entry entries[1];
+ } msr_data;
+ int ret;
+
+ if (env->tsc_valid) {
+ return 0;
+ }
+
+ msr_data.info.nmsrs = 1;
+ msr_data.entries[0].index = MSR_IA32_TSC;
+ env->tsc_valid = !runstate_is_running();
+
+ ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data);
+ if (ret < 0) {
+ return ret;
+ }
+
+ env->tsc = msr_data.entries[0].data;
+ return 0;
+}
+
+static inline void do_kvm_synchronize_tsc(void *arg)
+{
+ CPUState *cpu = arg;
+
+ kvm_get_tsc(cpu);
+}
+
+void kvm_synchronize_all_tsc(void)
+{
+ CPUState *cpu;
+
+ if (kvm_enabled()) {
+ CPU_FOREACH(cpu) {
+ run_on_cpu(cpu, do_kvm_synchronize_tsc, cpu);
+ }
+ }
+}
+
static struct kvm_cpuid2 *try_get_cpuid(KVMState *s, int max)
{
struct kvm_cpuid2 *cpuid;
diff --git a/qemu/target-i386/kvm_i386.h b/qemu/target-i386/kvm_i386.h
index e557e94f4..c1b312ba2 100644
--- a/qemu/target-i386/kvm_i386.h
+++ b/qemu/target-i386/kvm_i386.h
@@ -15,6 +15,7 @@
bool kvm_allows_irq0_override(void);
bool kvm_has_smm(void);
+void kvm_synchronize_all_tsc(void);
void kvm_arch_reset_vcpu(X86CPU *cs);
void kvm_arch_do_init_vcpu(X86CPU *cs);