Commit 384331a6 authored by Marcelo Tosatti's avatar Marcelo Tosatti
Browse files

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: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 75b10c43

target-i386/kvm.c

+9 −1
Original line number Diff line number Diff line
@@ -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 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);