linux-kernel - Re: [PATCH v4 01/20] irqchip/gic-v4.1: Skip absent CPUs while iterating over redistributors

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Message-ID: <1f86bcdd-01ca-4925-3163-d47e17d006ab@huawei.com>
Date:   Mon, 17 Feb 2020 17:11:47 +0800
From:   Zenghui Yu <yuzenghui@...wei.com>
To:     Marc Zyngier <maz@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jason Cooper <jason@...edaemon.net>,
        Robert Richter <rrichter@...vell.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Eric Auger <eric.auger@...hat.com>,
        "James Morse" <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: Re: [PATCH v4 01/20] irqchip/gic-v4.1: Skip absent CPUs while
 iterating over redistributors

Hi Marc,

On 2020/2/14 22:57, Marc Zyngier wrote:
> In a system that is only sparsly populated with CPUs, we can end-up with
> redistributors structures that are not initialized. Let's make sure we
> don't try and access those when iterating over them (in this case when
> checking we have a L2 VPE table).
> 
> Fixes: 4e6437f12d6e ("irqchip/gic-v4.1: Ensure L2 vPE table is allocated at RD level")
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> ---
>   drivers/irqchip/irq-gic-v3-its.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 83b1186ffcad..da883a691028 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -2452,6 +2452,10 @@ static bool allocate_vpe_l2_table(int cpu, u32 id)
>   	if (!gic_rdists->has_rvpeid)
>   		return true;
>   
> +	/* Skip non-present CPUs */
> +	if (!base)
> +		return true;
> +

Thanks for fixing this,

Reviewed-by: Zenghui Yu <yuzenghui@...wei.com>

>   	val  = gicr_read_vpropbaser(base + SZ_128K + GICR_VPROPBASER);
>   
>   	esz  = FIELD_GET(GICR_VPROPBASER_4_1_ENTRY_SIZE, val) + 1;
>