Re: [PATCH,RFC] iommu/amd: Use report_iommu_fault()

From: Joerg Roedel <joro@8bytes.org>
To: Lennert Buytenhek <buytenh@wantstofly.org>
Cc: iommu@lists.linux-foundation.org
Subject: Re: [PATCH,RFC] iommu/amd: Use report_iommu_fault()
Date: Mon, 26 Jul 2021 13:54:49 +0200	[thread overview]
Message-ID: <YP6iiR8wuszflhnN@8bytes.org> (raw)
In-Reply-To: <YPVL41ZO8Ih8WrKa@wantstofly.org>

Hi Lennert,

On Mon, Jul 19, 2021 at 12:54:43PM +0300, Lennert Buytenhek wrote:
> +	if (dev_data) {
> +		int report_flags;
> +
> +		/*
> +		 * AMD I/O Virtualization Technology (IOMMU) Specification,
> +		 * revision 3.00, section 2.5.3 ("IO_PAGE_FAULT Event") says
> +		 * that the RW ("read-write") bit is only valid if the I/O
> +		 * page fault was caused by a memory transaction request
> +		 * referencing a page that was marked present.
> +		 */
> +		report_flags = 0;
> +		if ((flags & (EVENT_FLAG_TR | EVENT_FLAG_PR | EVENT_FLAG_I)) ==
> +								EVENT_FLAG_PR) {
> +			if (flags & EVENT_FLAG_RW)
> +				report_flags |= IOMMU_FAULT_WRITE;
> +			else
> +				report_flags |= IOMMU_FAULT_READ;
> +		}
> +
> +		if (!report_iommu_fault(&dev_data->domain->domain,
> +					&pdev->dev, address, report_flags))
> +			goto out;
> +	}

I'd like to limit calling report_iommu_fault() to dma-faults and leave
IRQ remapping faults unreported. The IOMMU layer does not really care a
lot about IRQs and a potential domain handler will also not be prepared
to handler IRQ specific faults (there is no generic way to detect them).

Regards,

	Joerg
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