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author | 2015-12-08 09:14:07 +0800 | |
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committer | 2015-12-08 09:16:17 +0800 | |
commit | b52baab237a0b45cb18b26f529e6490b42574209 (patch) | |
tree | e8bd69d1ccf45f46381617d27cfdd1966abde0b1 /qemu/target-i386/kvm.c | |
parent | cc62f651747d5844cc12d33fb3620a7d05bae7dc (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The commit 317b0a6d8 fixed an issue which caused by the outdated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/kvm.c')
-rw-r--r-- | qemu/target-i386/kvm.c | 45 |
1 files changed, 45 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; |