linux-kernel - Re: [PATCH 06/11] RISC-V: drivers/iommu/riscv: Add command, fault, page-req queues

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Date:   Thu, 20 Jul 2023 06:11:58 +0300
From:   Nick Kossifidis <mick@....forth.gr>
To:     Tomasz Jeznach <tjeznach@...osinc.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <apatel@...tanamicro.com>,
        Sunil V L <sunilvl@...tanamicro.com>,
        Sebastien Boeuf <seb@...osinc.com>, iommu@...ts.linux.dev,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux@...osinc.com
Subject: Re: [PATCH 06/11] RISC-V: drivers/iommu/riscv: Add command, fault,
 page-req queues

Hello Tomasz,

On 7/19/23 22:33, Tomasz Jeznach wrote:
> Enables message or wire signal interrupts for PCIe and platforms devices.
> 

The description doesn't match the subject nor the patch content (we 
don't jus enable interrupts, we also init the queues).

> +	/* Parse Queue lengts */
> +	ret = of_property_read_u32(pdev->dev.of_node, "cmdq_len", &iommu->cmdq_len);
> +	if (!ret)
> +		dev_info(dev, "command queue length set to %i\n", iommu->cmdq_len);
> +
> +	ret = of_property_read_u32(pdev->dev.of_node, "fltq_len", &iommu->fltq_len);
> +	if (!ret)
> +		dev_info(dev, "fault/event queue length set to %i\n", iommu->fltq_len);
> +
> +	ret = of_property_read_u32(pdev->dev.of_node, "priq_len", &iommu->priq_len);
> +	if (!ret)
> +		dev_info(dev, "page request queue length set to %i\n", iommu->priq_len);
> +
>   	dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
>   

We need to add those to the device tree binding doc (or throw them away, 
I thought it would be better to have them as part of the device 
desciption than a module parameter).


> +static irqreturn_t riscv_iommu_priq_irq_check(int irq, void *data);
> +static irqreturn_t riscv_iommu_priq_process(int irq, void *data);
> +

> +	case RISCV_IOMMU_PAGE_REQUEST_QUEUE:
> +		q = &iommu->priq;
> +		q->len = sizeof(struct riscv_iommu_pq_record);
> +		count = iommu->priq_len;
> +		irq = iommu->irq_priq;
> +		irq_check = riscv_iommu_priq_irq_check;
> +		irq_process = riscv_iommu_priq_process;
> +		q->qbr = RISCV_IOMMU_REG_PQB;
> +		q->qcr = RISCV_IOMMU_REG_PQCSR;
> +		name = "priq";
> +		break;


It makes more sense to add the code for the page request queue in the 
patch that adds ATS/PRI support IMHO. This comment also applies to its 
interrupt handlers below.


> +static inline void riscv_iommu_cmd_inval_set_addr(struct riscv_iommu_command *cmd,
> +						  u64 addr)
> +{
> +	cmd->dword0 |= RISCV_IOMMU_CMD_IOTINVAL_AV;
> +	cmd->dword1 = addr;
> +}
> +

This needs to be (addr >> 2) to match the spec, same as in the iofence 
command.

Regards,
Nick