linux-kernel - Re: [PATCH v9 04/11] iommu: Add sva iommu

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Date:   Tue, 28 Jun 2022 19:33:57 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        Joerg Roedel <joro@...tes.org>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Raj, Ashok" <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        "Jiang, Dave" <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>
Cc:     baolu.lu@...ux.intel.com, Eric Auger <eric.auger@...hat.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v9 04/11] iommu: Add sva iommu_domain support

On 2022/6/28 16:50, Tian, Kevin wrote:
>> From: Baolu Lu<baolu.lu@...ux.intel.com>
>> Sent: Tuesday, June 28, 2022 1:41 PM
>>>>    struct iommu_domain {
>>>>    	unsigned type;
>>>>    	const struct iommu_domain_ops *ops;
>>>>    	unsigned long pgsize_bitmap;	/* Bitmap of page sizes in use */
>>>> -	iommu_fault_handler_t handler;
>>>> -	void *handler_token;
>>>>    	struct iommu_domain_geometry geometry;
>>>>    	struct iommu_dma_cookie *iova_cookie;
>>>> +	union {
>>>> +		struct {	/* IOMMU_DOMAIN_DMA */
>>>> +			iommu_fault_handler_t handler;
>>>> +			void *handler_token;
>>>> +		};
>>> why is it DMA domain specific? What about unmanaged
>>> domain? Unrecoverable fault can happen on any type
>>> including SVA. Hence I think above should be domain type
>>> agnostic.
>> The report_iommu_fault() should be replaced by the new
>> iommu_report_device_fault(). Jean has already started this work.
>>
>> https://lore.kernel.org/linux-iommu/Yo4Nw9QyllT1RZbd@myrica/
>>
>> Currently this is only for DMA domains, hence Robin suggested to make it
>> exclude with the SVA domain things.
>>
>> https://lore.kernel.org/linux-iommu/f3170016-4d7f-e78e-db48-
>> 68305f683349@....com/
> Then it's worthy a comment that those two fields are for
> some legacy fault reporting stuff and DMA type only.

The iommu_fault and SVA fields are exclusive. The former is used for
unrecoverable DMA remapping faults, while the latter is only interested
in the recoverable page faults.

I will update the commit message with above explanation. Does this work
for you?

Best regards,
baolu