Received-SPF: pass (google.com: domain of linux-kernel+bounces-211581-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Date: Wed, 12 Jun 2024 10:41:20 -0300
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: 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 04/10] iommu: Extend domain attach group with handle
 support
Message-ID: <20240612134120.GX791043@ziepe.ca>
References: <20240527040517.38561-1-baolu.lu@linux.intel.com>
 <20240527040517.38561-5-baolu.lu@linux.intel.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240527040517.38561-5-baolu.lu@linux.intel.com>

On Mon, May 27, 2024 at 12:05:11PM +0800, Lu Baolu wrote:
> Unlike the SVA case where each PASID of a device has an SVA domain
> attached to it, the I/O page faults are handled by the fault handler
> of the SVA domain. The I/O page faults for a user page table might
> be handled by the domain attached to RID or the domain attached to
> the PASID, depending on whether the PASID table is managed by user
> space or kernel. As a result, there is a need for the domain attach
> group interfaces to have attach handle support. The attach handle
> will be forwarded to the fault handler of the user domain.
> 
> Add some variants of the domain attaching group interfaces so that they
> could support the attach handle and export them for use in IOMMUFD.
> 
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
>  drivers/iommu/iommu-priv.h |  8 +++
>  drivers/iommu/iommu.c      | 99 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 107 insertions(+)

I don't have an objection to it like this, but I wonder if we could be
smaller to teach iommu_attach_device_pasid to use IOMMU_NO_PASID to
attach the handle to the rid?

It would have an if there to call the  __iommu_attach_group() instead
of the pasid attach ?

Jason