Re: [PATCH v1 5/8] iommu/amd: Use iommu_attach/detach_device()

From: Jason Gunthorpe via iommu <iommu@lists.linux-foundation.org>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Stuart Yoder <stuyoder@gmail.com>,
	rafael@kernel.org, David Airlie <airlied@linux.ie>,
	linux-pci@vger.kernel.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Diana Craciun <diana.craciun@oss.nxp.com>,
	Dmitry Osipenko <digetx@gmail.com>, Will Deacon <will@kernel.org>,
	Ashok Raj <ashok.raj@intel.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Christoph Hellwig <hch@infradead.org>,
	Kevin Tian <kevin.tian@intel.com>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	kvm@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Cornelia Huck <cohuck@redhat.com>,
	linux-kernel@vger.kernel.org, Li Yang <leoyang.li@nxp.com>,
	iommu@lists.linux-foundation.org,
	Jacob jun Pan <jacob.jun.pan@intel.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v1 5/8] iommu/amd: Use iommu_attach/detach_device()
Date: Thu, 6 Jan 2022 10:33:45 -0400	[thread overview]
Message-ID: <20220106143345.GC2328285@nvidia.com> (raw)
In-Reply-To: <20220106022053.2406748-6-baolu.lu@linux.intel.com>

On Thu, Jan 06, 2022 at 10:20:50AM +0800, Lu Baolu wrote:
> The individual device driver should use iommu_attach/detach_device()
> for domain attachment/detachment.
> 
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
>  drivers/iommu/amd/iommu_v2.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/amd/iommu_v2.c b/drivers/iommu/amd/iommu_v2.c
> index 58da08cc3d01..7d9d0fe89064 100644
> +++ b/drivers/iommu/amd/iommu_v2.c
> @@ -133,7 +133,7 @@ static void free_device_state(struct device_state *dev_state)
>  	if (WARN_ON(!group))
>  		return;
>  
> -	iommu_detach_group(dev_state->domain, group);
> +	iommu_detach_device(dev_state->domain, &dev_state->pdev->dev);
>  
>  	iommu_group_put(group);

This is the only user of the group in the function all the
group_get/put should be deleted too.

Joerg said in commit 55c99a4dc50f ("iommu/amd: Use
iommu_attach_group()") that the device API doesn't work here because
there are multi-device groups?

But I'm not sure how this can work with multi-device groups - this
seems to assigns a domain setup for direct map, so perhaps this only
works if all devices are setup for direct map?

> @@ -791,7 +791,7 @@ int amd_iommu_init_device(struct pci_dev *pdev, int pasids)
>  		goto out_free_domain;
>  	}
>  
> -	ret = iommu_attach_group(dev_state->domain, group);
> +	ret = iommu_attach_device(dev_state->domain, &pdev->dev);
>  	if (ret != 0)
>  		goto out_drop_group;

Same comment here

Jason
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