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Date:   Wed, 1 Sep 2021 22:10:13 +0000
From:   Oliver Upton <oupton@google.com>
To:     Raghavendra Rao Ananta <rananta@google.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>, Marc Zyngier <maz@kernel.org>,
        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
Subject: Re: [PATCH v3 03/12] KVM: arm64: selftests: Add support for cpu_relax
Message-ID: <YS/6RZG7Elr9fPQP@google.com>
References: <20210901211412.4171835-1-rananta@google.com>
 <20210901211412.4171835-4-rananta@google.com>
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On Wed, Sep 01, 2021 at 09:14:03PM +0000, Raghavendra Rao Ananta wrote:
> Implement the guest helper routine, cpu_relax(), to yield
> the processor to other tasks.
> 
> The function was derived from
> arch/arm64/include/asm/vdso/processor.h.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>

Reviewed-by: Oliver Upton <oupton@google.com>

> ---
>  tools/testing/selftests/kvm/include/aarch64/processor.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
> index 082cc97ad8d3..78df059dc974 100644
> --- a/tools/testing/selftests/kvm/include/aarch64/processor.h
> +++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
> @@ -191,6 +191,11 @@ asm(
>  	val;								  \
>  })
>  
> +static inline void cpu_relax(void)
> +{
> +	asm volatile("yield" ::: "memory");
> +}
> +
>  #define isb()		asm volatile("isb" : : : "memory")
>  #define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
>  #define dmb(opt)	asm volatile("dmb " #opt : : : "memory")
> -- 
> 2.33.0.153.gba50c8fa24-goog
>