linux-kernel - Re: [PATCH v2 11/36] irqchip/gic-v4.1: VPE table (aka GICR

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Date:   Tue, 24 Dec 2019 15:10:54 +0800
From:   Zenghui Yu <yuzenghui@...wei.com>
To:     Marc Zyngier <maz@...nel.org>, <kvmarm@...ts.cs.columbia.edu>,
        <linux-kernel@...r.kernel.org>
CC:     Eric Auger <eric.auger@...hat.com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        "Andrew Murray" <Andrew.Murray@....com>,
        Jayachandran C <jnair@...vell.com>,
        "Robert Richter" <rrichter@...vell.com>, <tangnianyao@...wei.com>,
        <wangwudi@...ilicon.com>
Subject: Re: [PATCH v2 11/36] irqchip/gic-v4.1: VPE table (aka
 GICR_VPROPBASER) allocation

Hi Marc,

[ +Wudi and Nianyao. As they spotted the following issue but
  I forgot to send it out. ]

On 2019/10/27 22:42, Marc Zyngier wrote:
> GICv4.1 defines a new VPE table that is potentially shared between
> both the ITSs and the redistributors, following complicated affinity
> rules.
> 
> To make things more confusing, the programming of this table at
> the redistributor level is reusing the GICv4.0 GICR_VPROPBASER register
> for something completely different.
> 
> The code flow is somewhat complexified by the need to respect the
> affinities required by the HW, meaning that tables can either be
> inherited from a previously discovered ITS or redistributor.
> 
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> ---[...]
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 40912b3fb0e1..478d3678850c 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
[...]
> @@ -2025,6 +2098,214 @@ static int its_alloc_tables(struct its_node *its)
>   	return 0;
>   }
>   
> +static u64 inherit_vpe_l1_table_from_its(void)
> +{
> +	struct its_node *its;
> +	u64 val;
> +	u32 aff;
> +
> +	val = gic_read_typer(gic_data_rdist_rd_base() + GICR_TYPER);
> +	aff = compute_common_aff(val);
> +
> +	list_for_each_entry(its, &its_nodes, entry) {
> +		u64 baser;
> +
> +		if (!is_v4_1(its))
> +			continue;
> +
> +		if (!FIELD_GET(GITS_TYPER_SVPET, its->typer))
> +			continue;
> +
> +		if (aff != compute_its_aff(its))
> +			continue;
> +
> +		/* GICv4.1 guarantees that the vPE table is GITS_BASER2 */
> +		baser = its->tables[2].val;
> +		if (!(baser & GITS_BASER_VALID))
> +			continue;
> +
> +		/* We have a winner! */
> +		val  = GICR_VPROPBASER_4_1_VALID;
> +		if (baser & GITS_BASER_INDIRECT)
> +			val |= GICR_VPROPBASER_4_1_INDIRECT;
> +		val |= FIELD_PREP(GICR_VPROPBASER_4_1_PAGE_SIZE,
> +				  FIELD_GET(GITS_BASER_PAGE_SIZE_MASK, baser));
> +		val |= FIELD_PREP(GICR_VPROPBASER_4_1_ADDR,
> +				  GITS_BASER_ADDR_48_to_52(baser) >> 12);

We've used GITS_BASER_ADDR_48_to_52() only in the KVM code where the
pagesize of ITS table is fixed to 64K.
It may not work when the pagesize is 4K or 16K?


Thanks,
Zenghui

> +		val |= FIELD_PREP(GICR_VPROPBASER_SHAREABILITY_MASK,
> +				  FIELD_GET(GITS_BASER_SHAREABILITY_MASK, baser));
> +		val |= FIELD_PREP(GICR_VPROPBASER_INNER_CACHEABILITY_MASK,
> +				  FIELD_GET(GITS_BASER_INNER_CACHEABILITY_MASK, baser));
> +		val |= FIELD_PREP(GICR_VPROPBASER_4_1_SIZE, GITS_BASER_NR_PAGES(baser) - 1);
> +
> +		return val;
> +	}
> +
> +	return 0;
> +}