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Subject: Re: [PATCH v5 05/23] irqchip/gic-v4.1: Ensure mutual exclusion betwen
 invalidations on the same RD
To:     Marc Zyngier <maz@kernel.org>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Jason Cooper <jason@lakedaemon.net>,
        Robert Richter <rrichter@marvell.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Zenghui Yu <yuzenghui@huawei.com>,
        James Morse <james.morse@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>
References: <20200304203330.4967-1-maz@kernel.org>
 <20200304203330.4967-6-maz@kernel.org>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <1722e947-2af8-7137-7e71-f6647cdf91d7@redhat.com>
Date:   Fri, 20 Mar 2020 15:23:47 +0100
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Hi,

On 3/4/20 9:33 PM, Marc Zyngier wrote:
> The GICv4.1 spec says that it is CONTRAINED UNPREDICTABLE to write to
> any of the GICR_INV{LPI,ALL}R registers if GICR_SYNCR.Busy == 1.
> 
> To deal with it, we must ensure that only a single invalidation can
> happen at a time for a given redistributor. Add a per-RD lock to that
> effect and take it around the invalidation/syncr-read to deal with this.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> ---
>  drivers/irqchip/irq-gic-v3-its.c   | 6 ++++++
>  drivers/irqchip/irq-gic-v3.c       | 1 +
>  include/linux/irqchip/arm-gic-v3.h | 1 +
>  3 files changed, 8 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index c84370245bea..fc5788584df7 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -1373,10 +1373,12 @@ static void direct_lpi_inv(struct irq_data *d)
>  
>  	/* Target the redistributor this LPI is currently routed to */
>  	cpu = irq_to_cpuid_lock(d, &flags);
> +	raw_spin_lock(&gic_data_rdist_cpu(cpu)->rd_lock);
>  	rdbase = per_cpu_ptr(gic_rdists->rdist, cpu)->rd_base;
>  	gic_write_lpir(val, rdbase + GICR_INVLPIR);
>  
>  	wait_for_syncr(rdbase);
> +	raw_spin_unlock(&gic_data_rdist_cpu(cpu)->rd_lock);
>  	irq_to_cpuid_unlock(d, flags);
>  }
>  
> @@ -3662,9 +3664,11 @@ static void its_vpe_send_inv(struct irq_data *d)
>  		void __iomem *rdbase;
>  
>  		/* Target the redistributor this VPE is currently known on */
> +		raw_spin_lock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
>  		rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base;
>  		gic_write_lpir(d->parent_data->hwirq, rdbase + GICR_INVLPIR);
>  		wait_for_syncr(rdbase);
> +		raw_spin_unlock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
>  	} else {
>  		its_vpe_send_cmd(vpe, its_send_inv);
>  	}
> @@ -3825,10 +3829,12 @@ static void its_vpe_4_1_invall(struct its_vpe *vpe)
>  	val |= FIELD_PREP(GICR_INVALLR_VPEID, vpe->vpe_id);
>  
>  	/* Target the redistributor this vPE is currently known on */
> +	raw_spin_lock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
>  	rdbase = per_cpu_ptr(gic_rdists->rdist, vpe->col_idx)->rd_base;
>  	gic_write_lpir(val, rdbase + GICR_INVALLR);
>  
>  	wait_for_syncr(rdbase);
> +	raw_spin_unlock(&gic_data_rdist_cpu(vpe->col_idx)->rd_lock);
>  }
>  
>  static int its_vpe_4_1_set_vcpu_affinity(struct irq_data *d, void *vcpu_info)
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 73e87e176d76..ba405becab53 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -835,6 +835,7 @@ static int __gic_populate_rdist(struct redist_region *region, void __iomem *ptr)
>  	typer = gic_read_typer(ptr + GICR_TYPER);
>  	if ((typer >> 32) == aff) {
>  		u64 offset = ptr - region->redist_base;
> +		raw_spin_lock_init(&gic_data_rdist()->rd_lock);
>  		gic_data_rdist_rd_base() = ptr;
>  		gic_data_rdist()->phys_base = region->phys_base + offset;
>  
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> index c29a02678a6f..b28acfa71f82 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -652,6 +652,7 @@
>  
>  struct rdists {
>  	struct {
> +		raw_spinlock_t	rd_lock;
>  		void __iomem	*rd_base;
>  		struct page	*pend_page;
>  		phys_addr_t	phys_base;
>