Re: [PATCH v2] LoongArch: KVM: Advertise already-supported capabilities

[Tao Cui]

Hi, Huacai

I missed my Signed-off-by tag for this patch, my mistake.
Could you append:
Signed-off-by: Tao Cui <cuitao@xxxxxxxxxx>
If it’s not workable, no problem at all.

于 2026年8月9日 GMT+08:00 12:06:36，Huacai Chen <chenhuacai@xxxxxxxxxx> 写道：
>Applied, thanks.
>
>Huacai
>
>On Wed, Aug 5, 2026 at 1:46 PM Tao Cui <cui.tao@xxxxxxxxx> wrote:
>>
>> Several LoongArch KVM features are fully implemented but were never
>> reported through their standard KVM_CHECK_EXTENSION probes, so userspace
>> cannot discover them.  Advertise the ones that already work and have a
>> real consumer:
>>
>>   - KVM_CAP_STEAL_TIME: steal time works end-to-end (host-side record
>>     plus guest paravirt side), and the probe returns kvm_pvtime_supported().
>>
>>   - KVM_CAP_VCPU_ATTRIBUTES: per-vCPU device-attribute ioctls are
>>     implemented (CPUCFG, PVTIME control); advertise the discovery cap.
>>
>> This adds no new functionality; it only makes existing features
>> discoverable via the standard probe.
>>
>> Signed-off-by: Tao Cui <cui.tao@xxxxxxxxx>
>> ---
>> Changes in v2:
>>   - Drop KVM_CAP_IRQFD_RESAMPLE: the only consumer is VFIO INTx, which
>>     needs IOMMU/VFIO not yet available on LoongArch.
>>   - Drop KVM_CAP_VM_GPA_BITS: the cap implies a GPA-width setter that
>>     LoongArch does not implement.
>>
>>  arch/loongarch/kvm/vm.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
>> index 1317c718f896..0a51931d6f6e 100644
>> --- a/arch/loongarch/kvm/vm.c
>> +++ b/arch/loongarch/kvm/vm.c
>> @@ -122,6 +122,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>         case KVM_CAP_IOEVENTFD:
>>         case KVM_CAP_MP_STATE:
>>         case KVM_CAP_SET_GUEST_DEBUG:
>> +       case KVM_CAP_VCPU_ATTRIBUTES:
>>                 r = 1;
>>                 break;
>>         case KVM_CAP_NR_VCPUS:
>> @@ -136,6 +137,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>         case KVM_CAP_NR_MEMSLOTS:
>>                 r = KVM_USER_MEM_SLOTS;
>>                 break;
>> +       case KVM_CAP_STEAL_TIME:
>> +               r = kvm_pvtime_supported();
>> +               break;
>>         default:
>>                 r = 0;
>>                 break;
>>