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port from upstream, commit id: 0fd7e098db30e302d27920487f0afec) The commit 317b0a6d8 fixed an issue which caused by the outdated env-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 ++---------------- 1 file changed, 2 insertions(+), 16 deletions(-) (limited to 'qemu/hw/i386/kvm') 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into X86CPU.apic_state too early, APIC state - * won't be reloaded later because CPUState.vcpu_dirty==true, and - * outdated APIC state may be migrated to another host. - * - * The real fix would be to make sure outdated APIC state is read - * from the kernel again when necessary.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) { -- cgit 1.2.3-korg