Commit d99569d9 authored by Eduardo Habkost's avatar Eduardo Habkost
Browse files

kvm: Allow invtsc migration if tsc-khz is set explicitly 



We can safely allow a VM to be migrated with invtsc enabled if
tsc-khz is set explicitly, because:
* QEMU already refuses to start if it can't set the TSC frequency
  to the configured value.
* Management software is already required to keep device
  configuration (including CPU configuration) the same on
  migration source and destination.

Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170108173234.25721-3-ehabkost@redhat.com>
Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
parent d74460ec

target/i386/kvm.c

+11 −9
Original line number Diff line number Diff line
@@ -963,6 +963,7 @@ int kvm_arch_init_vcpu(CPUState *cs) 
        has_msr_mcg_ext_ctl = has_msr_feature_control = true;

    }



    if (!env->user_tsc_khz) {

        if ((env->features[FEAT_8000_0007_EDX] & CPUID_APM_INVTSC) &&

            invtsc_mig_blocker == NULL) {

            /* for migration */
@@ -973,6 +974,7 @@ int kvm_arch_init_vcpu(CPUState *cs) 
            /* for savevm */

            vmstate_x86_cpu.unmigratable = 1;

        }

    }



    cpuid_data.cpuid.padding = 0;

    r = kvm_vcpu_ioctl(cs, KVM_SET_CPUID2, &cpuid_data);