linux-kernel - Re: [PATCH 05/10] Drivers: hv: vmbus: Handle auto EOI quirk inline

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Date:   Mon, 22 Feb 2021 11:30:19 +0800
From:   Boqun Feng <boqun.feng@...il.com>
To:     Michael Kelley <mikelley@...rosoft.com>
Cc:     sthemmin@...rosoft.com, kys@...rosoft.com, wei.liu@...nel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        daniel.lezcano@...aro.org, arnd@...db.de,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 05/10] Drivers: hv: vmbus: Handle auto EOI quirk inline

On Wed, Jan 27, 2021 at 12:23:40PM -0800, Michael Kelley wrote:
> On x86/x64, Hyper-V provides a flag to indicate auto EOI functionality,
> but it doesn't on ARM64. Handle this quirk inline instead of calling
> into code under arch/x86 (and coming, under arch/arm64).
> 
> No functional change.
> 
> Signed-off-by: Michael Kelley <mikelley@...rosoft.com>

Reviewed-by: Boqun Feng <boqun.feng@...il.com>

Regards,
Boqun

> ---
>  arch/x86/include/asm/mshyperv.h |  3 ---
>  drivers/hv/hv.c                 | 12 +++++++++++-
>  2 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index eba637d1..d12a188 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -27,9 +27,6 @@ static inline u64 hv_get_register(unsigned int reg)
>  	return value;
>  }
>  
> -#define hv_recommend_using_aeoi() \
> -	(!(ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED))
> -
>  #define hv_set_clocksource_vdso(val) \
>  	((val).vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK)
>  #define hv_enable_vdso_clocksource() \
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 0c1fa69..afe7a62 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -219,7 +219,17 @@ void hv_synic_enable_regs(unsigned int cpu)
>  
>  	shared_sint.vector = hv_get_vector();
>  	shared_sint.masked = false;
> -	shared_sint.auto_eoi = hv_recommend_using_aeoi();
> +
> +	/*
> +	 * On architectures where Hyper-V doesn't support AEOI (e.g., ARM64),
> +	 * it doesn't provide a recommendation flag and AEOI must be disabled.
> +	 */
> +#ifdef HV_DEPRECATING_AEOI_RECOMMENDED
> +	shared_sint.auto_eoi =
> +			!(ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED);
> +#else
> +	shared_sint.auto_eoi = 0;
> +#endif
>  	hv_set_register(HV_REGISTER_SINT0 + VMBUS_MESSAGE_SINT,
>  				shared_sint.as_uint64);
>  
> -- 
> 1.8.3.1
>