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Message-ID: <247f231c-3829-49c2-a8d9-11c3cc4b80ca@linux.intel.com>
Date: Thu, 13 Jun 2024 14:40:18 +0800
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Cc: baolu.lu@linux.intel.com, Kevin Tian <kevin.tian@intel.com>,
 Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
 Robin Murphy <robin.murphy@arm.com>,
 Jean-Philippe Brucker <jean-philippe@linaro.org>,
 Nicolin Chen <nicolinc@nvidia.com>, Yi Liu <yi.l.liu@intel.com>,
 Jacob Pan <jacob.jun.pan@linux.intel.com>,
 Joel Granados <j.granados@samsung.com>, iommu@lists.linux.dev,
 virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 05/10] iommufd: Add fault and response message
 definitions
To: Jason Gunthorpe <jgg@ziepe.ca>
References: <20240527040517.38561-1-baolu.lu@linux.intel.com>
 <20240527040517.38561-6-baolu.lu@linux.intel.com>
 <20240612135219.GZ791043@ziepe.ca>
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From: Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <20240612135219.GZ791043@ziepe.ca>
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On 6/12/24 9:52 PM, Jason Gunthorpe wrote:
> On Mon, May 27, 2024 at 12:05:12PM +0800, Lu Baolu wrote:
>> +/**
>> + * struct iommu_hwpt_pgfault - iommu page fault data
>> + * @size: sizeof(struct iommu_hwpt_pgfault)
>> + * @flags: Combination of enum iommu_hwpt_pgfault_flags
>> + * @dev_id: id of the originated device
>> + * @pasid: Process Address Space ID
>> + * @grpid: Page Request Group Index
>> + * @perm: Combination of enum iommu_hwpt_pgfault_perm
>> + * @addr: Fault address
>> + * @length: a hint of how much data the requestor is expecting to fetch. For
>> + *          example, if the PRI initiator knows it is going to do a 10MB
>> + *          transfer, it could fill in 10MB and the OS could pre-fault in
>> + *          10MB of IOVA. It's default to 0 if there's no such hint.
>> + * @cookie: kernel-managed cookie identifying a group of fault messages. The
>> + *          cookie number encoded in the last page fault of the group should
>> + *          be echoed back in the response message.
>> + */
>> +struct iommu_hwpt_pgfault {
>> +	__u32 size;
> Given we fail the system call if size is not exactly the right value
> we should probably drop it here.
> 
> The ioctl to get the FD can someday specify the format of the fault
> messages if we need to upgrade. If we want to change it down the road
> then the old FD will be exactly as it is now, and the user will
> request a new format FD that only works in whatever the new way is.

Okay, sure!

Best regards,
baolu