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Message-ID: <688a817f-b2e2-4620-ef4b-f3c5f73ae34d@redhat.com>
Date:   Thu, 5 May 2022 15:32:19 +0200
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Subject: Re: [PATCH] selftests: KVM: aarch64: Let hypercalls use UAPI
 *_BIT_COUNT
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To:     Marc Zyngier <maz@kernel.org>, Oliver Upton <oupton@google.com>
Cc:     Raghavendra Rao Ananta <rananta@google.com>,
        Andrew Jones <drjones@redhat.com>,
        James Morse <james.morse@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Peter Shier <pshier@google.com>,
        Ricardo Koller <ricarkol@google.com>,
        Reiji Watanabe <reijiw@google.com>,
        Jing Zhang <jingzhangos@google.com>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-kselftest@vger.kernel.org
References: <20220504184415.1905224-1-rananta@google.com>
 <YnLa8uH55/epyjlS@google.com> <87zgjw6v9k.wl-maz@kernel.org>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <87zgjw6v9k.wl-maz@kernel.org>
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On 5/5/22 14:04, Marc Zyngier wrote:
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index e523bb6eac67..3cde9f958eee 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -342,6 +342,10 @@ struct kvm_arm_copy_mte_tags {
>   
>   enum {
>   	KVM_REG_ARM_STD_BIT_TRNG_V1_0	= 0,
> +	/*
> +	 * KVM_REG_ARM_STD_BMAP_BIT_COUNT will vary as new services
> +	 * are added, and is explicitely not part of the ABI.
> +	 */
>   	KVM_REG_ARM_STD_BMAP_BIT_COUNT,
>   };

That seems like a bad idea.  Perhaps you can wrap it in #ifdef 
__KERNEL_OR_SELFTESTS__?  I can't find any prior art.

Paolo