On Fri, Mar 23, 2018 at 03:58:08PM +0300, Roman Kagan wrote:
> In order to guarantee compatibility on migration, QEMU should have
> complete control over the features it announces to the guest via CPUID.
>
> However, for a number of Hyper-V-related cpu properties, if the
> corresponding feature is not supported by the underlying KVM, the
> propery is silently ignored and the feature is not announced to the
> guest.
>
> Refuse to start with an error instead.
>
> Cc: qemu-sta...@nongnu.org
> Signed-off-by: Roman Kagan <rka...@virtuozzo.com>
I wonder if we should make these just warnings on -stable, and
make them fatal errors only on 2.12. I wouldn't want to make
existing running VMs not runnable on a stable update.
> ---
> target/i386/kvm.c | 25 +++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index fb20ff18c2..c9c359241c 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -658,17 +658,34 @@ static int hyperv_handle_properties(CPUState *cs)
> env->features[FEAT_HYPERV_EAX] |= HV_ACCESS_FREQUENCY_MSRS;
> env->features[FEAT_HYPERV_EDX] |= HV_FREQUENCY_MSRS_AVAILABLE;
> }
> - if (cpu->hyperv_crash && has_msr_hv_crash) {
> + if (cpu->hyperv_crash) {
> + if (!has_msr_hv_crash) {
> + fprintf(stderr,
> + "Hyper-V crash MSRs are not supported by kernel\n");
I would mention the corresponding "hv-..." -cpu option
explicitly, for clarity.
> + return -ENOSYS;
> + }
> env->features[FEAT_HYPERV_EDX] |= HV_GUEST_CRASH_MSR_AVAILABLE;
> }
> env->features[FEAT_HYPERV_EDX] |= HV_CPU_DYNAMIC_PARTITIONING_AVAILABLE;
> - if (cpu->hyperv_reset && has_msr_hv_reset) {
> + if (cpu->hyperv_reset) {
> + if (!has_msr_hv_reset) {
> + fprintf(stderr, "Hyper-V reset MSR is not supported by
> kernel\n");
> + return -ENOSYS;
> + }
> env->features[FEAT_HYPERV_EAX] |= HV_RESET_AVAILABLE;
> }
> - if (cpu->hyperv_vpindex && has_msr_hv_vpindex) {
> + if (cpu->hyperv_vpindex) {
> + if (!has_msr_hv_vpindex) {
> + fprintf(stderr, "Hyper-V VP_INDEX is not supported by kernel\n");
> + return -ENOSYS;
> + }
> env->features[FEAT_HYPERV_EAX] |= HV_VP_INDEX_AVAILABLE;
> }
> - if (cpu->hyperv_runtime && has_msr_hv_runtime) {
> + if (cpu->hyperv_runtime) {
> + if (!has_msr_hv_runtime) {
> + fprintf(stderr, "Hyper-V VP_INDEX is not supported by kernel\n");
> + return -ENOSYS;
> + }
> env->features[FEAT_HYPERV_EAX] |= HV_VP_RUNTIME_AVAILABLE;
> }
> if (cpu->hyperv_synic) {
> --
> 2.14.3
>
--
Eduardo
