On Sun, Nov 14, 2021, Shivam Kumar wrote:
> +static int kvm_vm_ioctl_enable_dirty_quota_migration(struct kvm *kvm,
> + bool enabled)
> +{
> + if (!KVM_DIRTY_LOG_PAGE_OFFSET)
I don't think we should force architectures to opt in. It would be trivial to
add
if (kvm_dirty_quota_is_full(vcpu)) {
vcpu->run->exit_reason = KVM_EXIT_DIRTY_QUOTA_FULL;
r = 0;
break;
}
in the run loops of each architecture. And we can do that in incremental patches
without #ifdeffery since it's only the exiting aspect that requires arch help.
> + return -EINVAL;
> +
> + /*
> + * For now, dirty quota migration works with dirty bitmap so don't
> + * enable it if dirty ring interface is enabled. In future, dirty
> + * quota migration may work with dirty ring interface was well.
> + */
Why does KVM care? This is a very simple concept. QEMU not using it for the
dirty ring doesn't mean KVM can't support it.
> + if (kvm->dirty_ring_size)
> + return -EINVAL;
> +
> + /* Return if no change */
> + if (kvm->dirty_quota_migration_enabled == enabled)
Needs to be check under lock.
> + return -EINVAL;
Probably more idiomatic to return 0 if the desired value is the current value.
> + mutex_lock(&kvm->lock);
> + kvm->dirty_quota_migration_enabled = enabled;
Needs to check vCPU creation.
> + mutex_unlock(&kvm->lock);
> +
> + return 0;
> +}
> +
> int __attribute__((weak)) kvm_vm_ioctl_enable_cap(struct kvm *kvm,
> struct kvm_enable_cap *cap)
> {
> @@ -4305,6 +4339,9 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm,
> }
> case KVM_CAP_DIRTY_LOG_RING:
> return kvm_vm_ioctl_enable_dirty_log_ring(kvm, cap->args[0]);
> + case KVM_CAP_DIRTY_QUOTA_MIGRATION:
> + return kvm_vm_ioctl_enable_dirty_quota_migration(kvm,
> + cap->args[0]);
> default:
> return kvm_vm_ioctl_enable_cap(kvm, cap);
> }
> --
> 2.22.3
>
