linux-kernel - Re: [PATCH] irqchip/gic-v4.1: Wait for completion of redistributor's INVALL operation

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Message-ID: <c46464a4c570e4aa12231bbd5ddefc07@kernel.org>
Date:   Mon, 02 Mar 2020 12:12:46 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Zenghui Yu <yuzenghui@...wei.com>
Cc:     linux-kernel@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
        tglx@...utronix.de, jason@...edaemon.net,
        wanghaibin.wang@...wei.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] irqchip/gic-v4.1: Wait for completion of redistributor's
 INVALL operation

On 2020-03-02 09:21, Zenghui Yu wrote:
> In GICv4.1, we emulate a guest-issued INVALL command by a direct write
> to GICR_INVALLR.  Before we finish the emulation and go back to guest,
> let's make sure the physical invalidate operation is actually completed
> and no stale data will be left in redistributor. Per the specification,
> this can be achieved by polling the GICR_SYNCR.Busy bit (to zero).
> 
> Signed-off-by: Zenghui Yu <yuzenghui@...wei.com>
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c 
> b/drivers/irqchip/irq-gic-v3-its.c
> index 83b1186ffcad..fc8c2970cee4 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -3784,6 +3784,8 @@ static void its_vpe_4_1_invall(struct its_vpe 
> *vpe)
>  	/* Target the redistributor this vPE is currently known on */
>  	rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base;
>  	gic_write_lpir(val, rdbase + GICR_INVALLR);
> +
> +	wait_for_syncr(rdbase);
>  }
> 
>  static int its_vpe_4_1_set_vcpu_affinity(struct irq_data *d, void 
> *vcpu_info)

Yup, well spotted. I'll add that to the series.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...