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Date: Tue, 7 May 2024 20:58:47 -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 v5 2/9] iommu: Replace sva_iommu with iommu_attach_handle
Message-ID: <20240507235847.GL4718@ziepe.ca>
References: <20240430145710.68112-1-baolu.lu@linux.intel.com>
 <20240430145710.68112-3-baolu.lu@linux.intel.com>
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In-Reply-To: <20240430145710.68112-3-baolu.lu@linux.intel.com>

On Tue, Apr 30, 2024 at 10:57:03PM +0800, Lu Baolu wrote:
> diff --git a/drivers/iommu/iommu-priv.h b/drivers/iommu/iommu-priv.h
> index da1addaa1a31..ae65e0b85d69 100644
> --- a/drivers/iommu/iommu-priv.h
> +++ b/drivers/iommu/iommu-priv.h
> @@ -30,6 +30,13 @@ void iommu_device_unregister_bus(struct iommu_device *iommu,
>  
>  struct iommu_attach_handle {
>  	struct iommu_domain		*domain;
> +	union {
> +		/* attach data for SVA domain */
> +		struct {
> +			struct device	*dev;
> +			refcount_t	users;
> +		};
> +	};
>  };

FWIW I was thinking of having the caller allocate the handle and pass it
down, but this seems workable too and is a bit simpler.

> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index bdc2e6fda782..b325097421c1 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -106,7 +106,7 @@ static long uacce_fops_compat_ioctl(struct file *filep,
>  static int uacce_bind_queue(struct uacce_device *uacce, struct uacce_queue *q)
>  {
>  	u32 pasid;
> -	struct iommu_sva *handle;
> +	struct iommu_attach_handle *handle;

Though I'm much less keen on this..

Maybe

  struct iommu_attach_handle {
  	struct iommu_domain		*domain;
 	union {
	      struct iommu_sva sva;
 	};
  };

?

Then container_of(sva) to get back to handle and keep the meaningful
type?

Jason