linux-kernel - Re: [PATCH v5 07/23] irqchip/gic-v4.1: Map the ITS SGIR register page

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Date:   Mon, 16 Mar 2020 18:10:21 +0100
From:   Auger Eric <eric.auger@...hat.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>,
        Zenghui Yu <yuzenghui@...wei.com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: Re: [PATCH v5 07/23] irqchip/gic-v4.1: Map the ITS SGIR register page

Hi Marc,

On 3/4/20 9:33 PM, Marc Zyngier wrote:
> One of the new features of GICv4.1 is to allow virtual SGIs to be
> directly signaled to a VPE. For that, the ITS has grown a new
> 64kB page containing only a single register that is used to
> signal a SGI to a given VPE.
> 
> Add a second mapping covering this new 64kB range, and take this
> opportunity to limit the original mapping to 64kB, which is enough
> to cover the span of the ITS registers.
> 
> Signed-off-by: Marc Zyngier <maz@...nel.org>
> Reviewed-by: Zenghui Yu <yuzenghui@...wei.com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>

Eric
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index bcc1a0957cda..54d6fdf7a28e 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -96,6 +96,7 @@ struct its_node {
>  	struct mutex		dev_alloc_lock;
>  	struct list_head	entry;
>  	void __iomem		*base;
> +	void __iomem		*sgir_base;
>  	phys_addr_t		phys_base;
>  	struct its_cmd_block	*cmd_base;
>  	struct its_cmd_block	*cmd_write;
> @@ -4456,7 +4457,7 @@ static int __init its_probe_one(struct resource *res,
>  	struct page *page;
>  	int err;
>  
> -	its_base = ioremap(res->start, resource_size(res));
> +	its_base = ioremap(res->start, SZ_64K);
>  	if (!its_base) {
>  		pr_warn("ITS@%pa: Unable to map ITS registers\n", &res->start);
>  		return -ENOMEM;
> @@ -4507,6 +4508,13 @@ static int __init its_probe_one(struct resource *res,
>  
>  		if (is_v4_1(its)) {
>  			u32 svpet = FIELD_GET(GITS_TYPER_SVPET, typer);
> +
> +			its->sgir_base = ioremap(res->start + SZ_128K, SZ_64K);
> +			if (!its->sgir_base) {
> +				err = -ENOMEM;
> +				goto out_free_its;
> +			}
> +
>  			its->mpidr = readl_relaxed(its_base + GITS_MPIDR);
>  
>  			pr_info("ITS@%pa: Using GICv4.1 mode %08x %08x\n",
> @@ -4520,7 +4528,7 @@ static int __init its_probe_one(struct resource *res,
>  				get_order(ITS_CMD_QUEUE_SZ));
>  	if (!page) {
>  		err = -ENOMEM;
> -		goto out_free_its;
> +		goto out_unmap_sgir;
>  	}
>  	its->cmd_base = (void *)page_address(page);
>  	its->cmd_write = its->cmd_base;
> @@ -4587,6 +4595,9 @@ static int __init its_probe_one(struct resource *res,
>  	its_free_tables(its);
>  out_free_cmd:
>  	free_pages((unsigned long)its->cmd_base, get_order(ITS_CMD_QUEUE_SZ));
> +out_unmap_sgir:
> +	if (its->sgir_base)
> +		iounmap(its->sgir_base);
>  out_free_its:
>  	kfree(its);
>  out_unmap:
>