diff options
| -rw-r--r-- | docs/hyperv.txt | 5 | ||||
| -rw-r--r-- | target/i386/kvm/hyperv-proto.h | 1 | ||||
| -rw-r--r-- | target/i386/machine.c | 20 |
3 files changed, 26 insertions, 0 deletions
diff --git a/docs/hyperv.txt b/docs/hyperv.txt index 5df00da54f..e53c581f45 100644 --- a/docs/hyperv.txt +++ b/docs/hyperv.txt @@ -160,6 +160,11 @@ the hypervisor) until it is ready to switch to the new one. This, in conjunction with hv-frequencies, allows Hyper-V on KVM to pass stable clocksource (Reference TSC page) to its own guests. +Note, KVM doesn't fully support re-enlightenment notifications and doesn't +emulate TSC accesses after migration so 'tsc-frequency=' CPU option also has to +be specified to make migration succeed. The destination host has to either have +the same TSC frequency or support TSC scaling CPU feature. + Recommended: hv-frequencies 3.16. hv-evmcs diff --git a/target/i386/kvm/hyperv-proto.h b/target/i386/kvm/hyperv-proto.h index 056a305be3..e30d64b4ad 100644 --- a/target/i386/kvm/hyperv-proto.h +++ b/target/i386/kvm/hyperv-proto.h @@ -139,6 +139,7 @@ * Reenlightenment notification MSRs */ #define HV_X64_MSR_REENLIGHTENMENT_CONTROL 0x40000106 +#define HV_REENLIGHTENMENT_ENABLE_BIT (1u << 16) #define HV_X64_MSR_TSC_EMULATION_CONTROL 0x40000107 #define HV_X64_MSR_TSC_EMULATION_STATUS 0x40000108 diff --git a/target/i386/machine.c b/target/i386/machine.c index 7259fe6868..137604ddb8 100644 --- a/target/i386/machine.c +++ b/target/i386/machine.c @@ -883,11 +883,31 @@ static bool hyperv_reenlightenment_enable_needed(void *opaque) env->msr_hv_tsc_emulation_status != 0; } +static int hyperv_reenlightenment_post_load(void *opaque, int version_id) +{ + X86CPU *cpu = opaque; + CPUX86State *env = &cpu->env; + + /* + * KVM doesn't fully support re-enlightenment notifications so we need to + * make sure TSC frequency doesn't change upon migration. + */ + if ((env->msr_hv_reenlightenment_control & HV_REENLIGHTENMENT_ENABLE_BIT) && + !env->user_tsc_khz) { + error_report("Guest enabled re-enlightenment notifications, " + "'tsc-frequency=' has to be specified"); + return -EINVAL; + } + + return 0; +} + static const VMStateDescription vmstate_msr_hyperv_reenlightenment = { .name = "cpu/msr_hyperv_reenlightenment", .version_id = 1, .minimum_version_id = 1, .needed = hyperv_reenlightenment_enable_needed, + .post_load = hyperv_reenlightenment_post_load, .fields = (VMStateField[]) { VMSTATE_UINT64(env.msr_hv_reenlightenment_control, X86CPU), VMSTATE_UINT64(env.msr_hv_tsc_emulation_control, X86CPU), |