linux-kernel - Re: [PATCH 20/35] irqchip/gic-v4.1: Allow direct invalidation of VLPIs

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Message-ID: <db01f956-bc53-b8a5-9406-15b889d717f0@huawei.com>
Date:   Sat, 28 Sep 2019 10:02:07 +0800
From:   Zenghui Yu <yuzenghui@...wei.com>
To:     Marc Zyngier <maz@...nel.org>, <kvmarm@...ts.cs.columbia.edu>,
        <linux-kernel@...r.kernel.org>
CC:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jason Cooper <jason@...edaemon.net>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 20/35] irqchip/gic-v4.1: Allow direct invalidation of
 VLPIs

On 2019/9/24 2:25, Marc Zyngier wrote:
> Just like for INVALL, GICv4.1 has grown a VPE-aware INVLPI register.
> Let's plumb it in and make use of the DirectLPI code in that case.
> 
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> ---
>   drivers/irqchip/irq-gic-v3-its.c   | 19 +++++++++++++++++--
>   include/linux/irqchip/arm-gic-v3.h |  1 +
>   2 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index b791c9beddf2..34595a7fcccb 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -1200,13 +1200,27 @@ static void wait_for_syncr(void __iomem *rdbase)
>   
>   static void direct_lpi_inv(struct irq_data *d)
>   {
> +	struct its_vlpi_map *map = get_vlpi_map(d);
>   	struct its_collection *col;
>   	void __iomem *rdbase;
> +	u64 val;
> +
> +	if (map) {
> +		struct its_device *its_dev = irq_data_get_irq_chip_data(d);
> +
> +		WARN_ON(!is_v4_1(its_dev->its));
> +
> +		val  = GICR_INVLPIR_V;
> +		val |= FIELD_PREP(GICR_INVLPIR_VPEID, map->vpe->vpe_id);
> +		val |= FIELD_PREP(GICR_INVLPIR_INTID, map->vintid);
> +	} else {
> +		val = d->hwirq;
> +	}
>   
>   	/* Target the redistributor this LPI is currently routed to */
>   	col = irq_to_col(d);

I think irq_to_col() may not work when GICv4.1 VLPIs are involved in.

irq_to_col() gives us col_map[event] as the target redistributor,
but the correct one for VLPIs should be vlpi_maps[event]->vpe->col_idx.
These two are not always pointing to the same physical RD.
For example, if guest issues a MOVI against a VLPI, we will update the
corresponding vlpi_map->vpe and issue a VMOVI on ITS... but leave the
col_map[event] unchanged.

col_map[event] usually describes the physical LPI's CPU affinity, but
when this physical LPI serves as something which the VLPI is backed by,
we take really little care of it.  Did I miss something here?


Thanks,
zenghui


>   	rdbase = per_cpu_ptr(gic_rdists->rdist, col->col_id)->rd_base;
> -	gic_write_lpir(d->hwirq, rdbase + GICR_INVLPIR);
> +	gic_write_lpir(val, rdbase + GICR_INVLPIR);
>   
>   	wait_for_syncr(rdbase);
>   }
> @@ -1216,7 +1230,8 @@ static void lpi_update_config(struct irq_data *d, u8 clr, u8 set)
>   	struct its_device *its_dev = irq_data_get_irq_chip_data(d);
>   
>   	lpi_write_config(d, clr, set);
> -	if (gic_rdists->has_direct_lpi && !irqd_is_forwarded_to_vcpu(d))
> +	if (gic_rdists->has_direct_lpi &&
> +	    (is_v4_1(its_dev->its) || !irqd_is_forwarded_to_vcpu(d)))
>   		direct_lpi_inv(d);
>   	else
>   		its_send_inv(its_dev, its_get_event_id(d));
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> index b69f60792554..5f3278cbf247 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -247,6 +247,7 @@
>   #define GICR_TYPER_COMMON_LPI_AFF	GENMASK_ULL(25, 24)
>   #define GICR_TYPER_AFFINITY		GENMASK_ULL(63, 32)
>   
> +#define GICR_INVLPIR_INTID		GENMASK_ULL(31, 0)
>   #define GICR_INVLPIR_VPEID		GENMASK_ULL(47, 32)
>   #define GICR_INVLPIR_V			GENMASK_ULL(63, 63)
>   
>