On Wed, Feb 15 2023, Eric Auger <eau...@redhat.com> wrote:
> Hi Richard,
> On 2/6/23 19:27, Richard Henderson wrote:
>> On 2/6/23 03:32, Eric Auger wrote:
>>>> +void kvm_arm_enable_mte(Error **errp)
>>>> +{
>>>> + static bool tried_to_enable = false;
>>>> + Error *mte_migration_blocker = NULL;
>>> can't you make the mte_migration_blocker static instead?
>>>
>>>> + int ret;
>>>> +
>>>> + if (tried_to_enable) {
>>>> + /*
>>>> + * MTE on KVM is enabled on a per-VM basis (and retrying
>>>> doesn't make
>>>> + * sense), and we only want a single migration blocker as well.
>>>> + */
>>>> + return;
>>>> + }
>>>> + tried_to_enable = true;
>>>> +
>>>> + if ((ret = kvm_vm_enable_cap(kvm_state, KVM_CAP_ARM_MTE, 0))) {
>>>> + error_setg_errno(errp, -ret, "Failed to enable
>>>> KVM_CAP_ARM_MTE");
>>>> + return;
>>>> + }
>>>> +
>>>> + /* TODO: add proper migration support with MTE enabled */
>>>> + error_setg(&mte_migration_blocker,
>>>> + "Live migration disabled due to MTE enabled");
>>
>> Making the blocker static wouldn't stop multiple errors from
>> kvm_vm_enable_cap.
> Sorry I don't get what you mean. instead of checking tried_to_enable why
> can't we check !mte_migration_blocker?
[missed this one]
Do you mean
if (mte_migration_blocker) {
return;
}
error_setg(&mte_migration_blocker, ...);
if ((ret = kvm_vm_enable_cap(...))) {
return;
}
if (migrate_add_blocker(...)) {
error_free(mte_migration_blocker);
// is mte_migration_blocker guaranteed != NULL here?
}
