linux-kernel - Re: [PATCH] KVM: arm64: selftests: Request PMU feature in get-reg-list

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Date:   Thu, 13 May 2021 23:20:49 +1000
From:   Gavin Shan <gshan@...hat.com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, drjones@...hat.com,
        pbonzini@...hat.com
Subject: Re: [PATCH] KVM: arm64: selftests: Request PMU feature in
 get-reg-list

On 5/13/21 9:14 PM, Marc Zyngier wrote:
> On 2021-05-13 14:06, Gavin Shan wrote:
>> Since the following commit, PMU registers are hidden from user until
>> it's explicitly requested by feeding feature (KVM_ARM_VCPU_PMU_V3).
>> Otherwise, 74 missing PMU registers are missing as the following
>> log indicates.
>>
>>    11663111cd49 ("KVM: arm64: Hide PMU registers from userspace when
>> not available")
>>
>>    # ./get-reg-list
>>    Number blessed registers:   308
>>    Number registers:           238
>>
>>    There are 74 missing registers.
>>    The following lines are missing registers:
>>
>>           ARM64_SYS_REG(3, 0, 9, 14, 1),
>>     ARM64_SYS_REG(3, 0, 9, 14, 2),
>>              :
>>     ARM64_SYS_REG(3, 3, 14, 15, 7),
>>
>> This fixes the issue of wrongly reported missing PMU registers by
>> requesting it explicitly.
>>
>> Signed-off-by: Gavin Shan <gshan@...hat.com>
>> ---
>>  tools/testing/selftests/kvm/aarch64/get-reg-list.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/tools/testing/selftests/kvm/aarch64/get-reg-list.c
>> b/tools/testing/selftests/kvm/aarch64/get-reg-list.c
>> index 486932164cf2..6c6bdc6f5dc3 100644
>> --- a/tools/testing/selftests/kvm/aarch64/get-reg-list.c
>> +++ b/tools/testing/selftests/kvm/aarch64/get-reg-list.c
>> @@ -314,6 +314,8 @@ static void core_reg_fixup(void)
>>
>>  static void prepare_vcpu_init(struct kvm_vcpu_init *init)
>>  {
>> +    init->features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
>> +
>>      if (reg_list_sve())
>>          init->features[0] |= 1 << KVM_ARM_VCPU_SVE;
>>  }
> 
> Please see Andrew's series[1], which actually deals with options.
> 
>          M.
> 
> [1] https://lore.kernel.org/r/20210507200416.198055-1-drjones@redhat.com
>

Thanks, Marc. Yes, Drew's series already had the fix.
Sorry about the noise and please ignore this.

Thanks,
Gavin