Drop kvm_load_tsc in favor of level-dependent writeback in kvm_arch_load_regs. KVM's PV clock MSRs fall in the same category and should therefore only be written back on full sync. Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> --- qemu-kvm-x86.c | 27 +++++++++++++-------------- qemu-kvm.h | 4 ---- target-i386/machine.c | 5 ----- 3 files changed, 13 insertions(+), 23 deletions(-) diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c index c838a8b..8d30b05 100644 --- a/qemu-kvm-x86.c +++ b/qemu-kvm-x86.c @@ -965,8 +965,19 @@ void kvm_arch_load_regs(CPUState *env, int level) set_msr_entry(&msrs[n++], MSR_LSTAR , env->lstar); } #endif - set_msr_entry(&msrs[n++], MSR_KVM_SYSTEM_TIME, env->system_time_msr); - set_msr_entry(&msrs[n++], MSR_KVM_WALL_CLOCK, env->wall_clock_msr); + if (level == KVM_PUT_FULL_STATE) { + /* + * 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) { + set_msr_entry(&msrs[n++], MSR_IA32_TSC, env->tsc); + } + set_msr_entry(&msrs[n++], MSR_KVM_SYSTEM_TIME, env->system_time_msr); + set_msr_entry(&msrs[n++], MSR_KVM_WALL_CLOCK, env->wall_clock_msr); + } rc = kvm_set_msrs(env, msrs, n); if (rc == -1) @@ -986,18 +997,6 @@ void kvm_arch_load_regs(CPUState *env, int level) kvm_guest_debug_workarounds(env); } -void kvm_load_tsc(CPUState *env) -{ - int rc; - struct kvm_msr_entry msr; - - set_msr_entry(&msr, MSR_IA32_TSC, env->tsc); - - rc = kvm_set_msrs(env, &msr, 1); - if (rc == -1) - perror("kvm_set_tsc FAILED.\n"); -} - void kvm_arch_save_regs(CPUState *env) { struct kvm_regs regs; diff --git a/qemu-kvm.h b/qemu-kvm.h index 7ad8f42..5c0b660 100644 --- a/qemu-kvm.h +++ b/qemu-kvm.h @@ -943,7 +943,6 @@ int handle_tpr_access(void *opaque, CPUState *env, uint64_t rip, #ifdef TARGET_I386 #define qemu_kvm_has_pit_state2() kvm_has_pit_state2(kvm_context) #endif -void kvm_load_tsc(CPUState *env); #else #define kvm_nested 0 #define qemu_kvm_has_gsi_routing() (0) @@ -951,9 +950,6 @@ void kvm_load_tsc(CPUState *env); #define qemu_kvm_has_pit_state2() (0) #endif #define qemu_kvm_cpu_stop(env) do {} while(0) -static inline void kvm_load_tsc(CPUState *env) -{ -} #endif void kvm_mutex_unlock(void); diff --git a/target-i386/machine.c b/target-i386/machine.c index bcc315b..b547e2a 100644 --- a/target-i386/machine.c +++ b/target-i386/machine.c @@ -354,11 +354,6 @@ static int cpu_post_load(void *opaque, int version_id) hw_breakpoint_insert(env, i); tlb_flush(env, 1); - - if (kvm_enabled()) { - kvm_load_tsc(env); - } - return 0; } -- 1.6.0.2 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html