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

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Message-ID: <d717b9272cce16c62a4e3e671bb1f068@kernel.org>
Date:   Thu, 13 May 2021 12:14:22 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Gavin Shan <gshan@...hat.com>
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 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
-- 
Jazz is not dead. It just smells funny...