diff options
| author | Marcelo Tosatti <mtosatti@redhat.com> | 2010-10-21 13:35:03 -0200 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2010-10-21 13:37:40 -0200 |
| commit | 384331a61a8ca42f32516ced20cb52470c5f6f57 (patch) | |
| tree | f64c77db9ac9df9b4afc06ff1f2d75fa93bb2a48 | |
| parent | 75b10c43365e2a9cab5398f31b96a463b0d57eff (diff) | |
kvm: writeback SMP TSCs on migration only
commit 6389c45441269baa2873e6feafebd17105ddeaf6
Author: Jan Kiszka <jan.kiszka@siemens.com>
Date: Mon Mar 1 18:17:26 2010 +0100
qemu-kvm: Cleanup/fix TSC and PV clock writeback
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
| -rw-r--r-- | target-i386/kvm.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/target-i386/kvm.c b/target-i386/kvm.c index 06474d6161..e2f7e2ef4a 100644 --- a/target-i386/kvm.c +++ b/target-i386/kvm.c @@ -817,7 +817,15 @@ static int kvm_put_msrs(CPUState *env, int level) kvm_msr_entry_set(&msrs[n++], MSR_LSTAR, env->lstar); #endif if (level == KVM_PUT_FULL_STATE) { - kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSC, env->tsc); + /* + * KVM is yet unable to synchronize TSC values of multiple VCPUs on + * writeback. Until this is fixed, we only write the offset to SMP + * guests after migration, desynchronizing the VCPUs, but avoiding + * huge jump-backs that would occur without any writeback at all. + */ + if (smp_cpus == 1 || env->tsc != 0) { + kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSC, env->tsc); + } kvm_msr_entry_set(&msrs[n++], MSR_KVM_SYSTEM_TIME, env->system_time_msr); kvm_msr_entry_set(&msrs[n++], MSR_KVM_WALL_CLOCK, env->wall_clock_msr); |