[PATCH v2 1/3] KVM: Add capability to advertise PSCI v0.2 support

[Anup Patel]

On Mon, Feb 3, 2014 at 5:18 PM, Mark Rutland <mark.rutland at arm.com> wrote:
> On Thu, Jan 30, 2014 at 10:41:17AM +0000, Anup Patel wrote:
>> User space (i.e. QEMU or KVMTOOL) should be able to check whether KVM
>> ARM/ARM64 supports in-kernel PSCI v0.2 emulation. For this purpose, we
>> define KVM_CAP_ARM_PSCI_0_2 in KVM user space interface header.
>>
>> Signed-off-by: Anup Patel <anup.patel at linaro.org>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar at linaro.org>
>> ---
>>  include/uapi/linux/kvm.h |    1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 902f124..d64349e 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -674,6 +674,7 @@ struct kvm_ppc_smmu_info {
>>  #define KVM_CAP_ARM_EL1_32BIT 93
>>  #define KVM_CAP_SPAPR_MULTITCE 94
>>  #define KVM_CAP_EXT_EMUL_CPUID 95
>> +#define KVM_CAP_ARM_PSCI_0_2 96
>
> To reiterate the point I made on patch 2, this does not do what it says
> on the tin, and does not make sense without mandatory PSCI 0.2
> functionality being present, as no software can derive any value from
> this flag until such functionality is implemented.

I handle this situation I would suggest to not advertise PSCI v0.2
capability to user space till all mandatory PSCI v0.2 functions
are implemented. We will also need to defer the change in
arch/arm/kvm/arm.c done by patch 2.

Regards,
Anup

>
> Thanks,
> Mark.
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