From b52baab237a0b45cb18b26f529e6490b42574209 Mon Sep 17 00:00:00 2001 From: Liang Li Date: Tue, 8 Dec 2015 09:14:07 +0800 Subject: kvmclock: add a new function to update env->tsc. (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port from upstream, commit id: 0fd7e098db30e302d27920487f0afec) The commit 317b0a6d8 fixed an issue which caused by the outdated env-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 Message-Id: <1446695464-27116-2-git-send-email-liang.z.li@intel.com> Signed-off-by: Paolo Bonzini --- qemu/hw/i386/kvm/clock.c | 18 ++---------------- qemu/target-i386/kvm.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ qemu/target-i386/kvm_i386.h | 1 + 3 files changed, 48 insertions(+), 16 deletions(-) diff --git a/qemu/hw/i386/kvm/clock.c b/qemu/hw/i386/kvm/clock.c index efdf16584..0593a3f1f 100644 --- a/qemu/hw/i386/kvm/clock.c +++ b/qemu/hw/i386/kvm/clock.c @@ -17,7 +17,7 @@ #include "qemu/host-utils.h" #include "sysemu/sysemu.h" #include "sysemu/kvm.h" -#include "sysemu/cpus.h" +#include "kvm_i386.h" #include "hw/sysbus.h" #include "hw/kvm/clock.h" @@ -125,21 +125,7 @@ static void kvmclock_vm_state_change(void *opaque, int running, return; } - cpu_synchronize_all_states(); - /* In theory, the cpu_synchronize_all_states() call above wouldn't - * affect the rest of the code, as the VCPU state inside CPUState - * is supposed to always match the VCPU state on the kernel side. - * - * In practice, calling cpu_synchronize_state() too soon will load the - * kernel-side APIC state into X86CPU.apic_state too early, APIC state - * won't be reloaded later because CPUState.vcpu_dirty==true, and - * outdated APIC state may be migrated to another host. - * - * The real fix would be to make sure outdated APIC state is read - * from the kernel again when necessary. While this is not fixed, we - * need the cpu_clean_all_dirty() call below. - */ - cpu_clean_all_dirty(); + kvm_synchronize_all_tsc(); ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data); if (ret < 0) { 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); -- cgit 1.2.3-korg