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Date:   Sun, 31 Jul 2022 20:19:04 +0800
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Subject: Re: [PATCH v10 05/12] iommu: Add IOMMU SVA domain support
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To:     Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Christoph Hellwig <hch@infradead.org>,
        Kevin Tian <kevin.tian@intel.com>,
        Ashok Raj <ashok.raj@intel.com>,
        "Will Deacon" <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        "Jean-Philippe Brucker" <jean-philippe@linaro.com>,
        Dave Jiang <dave.jiang@intel.com>,
        "Vinod Koul" <vkoul@kernel.org>
CC:     Eric Auger <eric.auger@redhat.com>,
        Jacob jun Pan <jacob.jun.pan@intel.com>,
        Zhangfei Gao <zhangfei.gao@linaro.org>,
        Zhu Tony <tony.zhu@intel.com>, <iommu@lists.linux.dev>,
        <linux-kernel@vger.kernel.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>
References: <20220705050710.2887204-1-baolu.lu@linux.intel.com>
 <20220705050710.2887204-6-baolu.lu@linux.intel.com>
From:   Yi Liu <yi.l.liu@intel.com>
In-Reply-To: <20220705050710.2887204-6-baolu.lu@linux.intel.com>
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On 2022/7/5 13:07, Lu Baolu wrote:
> The sva iommu_domain represents a hardware pagetable that the IOMMU
> hardware could use for SVA translation. This adds some infrastructure
> to support SVA domain in the iommu common layer. It includes:
> 
> - Extend the iommu_domain to support a new IOMMU_DOMAIN_SVA domain
>    type. The IOMMU drivers that support allocation of the SVA domain
>    should provide its own sva domain specific iommu_domain_ops.
> - Add a helper to allocate an SVA domain. The iommu_domain_free()
>    is still used to free an SVA domain.
> 
> The report_iommu_fault() should be replaced by the new
> iommu_report_device_fault(). Leave the existing fault handler with the
> existing users and the newly added SVA members excludes it.
> 
> Suggested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
> Tested-by: Tony Zhu <tony.zhu@intel.com>
> ---
>   include/linux/iommu.h | 24 ++++++++++++++++++++++--
>   drivers/iommu/iommu.c | 20 ++++++++++++++++++++
>   2 files changed, 42 insertions(+), 2 deletions(-)

Reviewed-by: Yi Liu <yi.l.liu@intel.com>

> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index f2b5aa7efe43..42f0418dc22c 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -64,6 +64,8 @@ struct iommu_domain_geometry {
>   #define __IOMMU_DOMAIN_PT	(1U << 2)  /* Domain is identity mapped   */
>   #define __IOMMU_DOMAIN_DMA_FQ	(1U << 3)  /* DMA-API uses flush queue    */
>   
> +#define __IOMMU_DOMAIN_SVA	(1U << 4)  /* Shared process address space */
> +
>   /*
>    * This are the possible domain-types
>    *
> @@ -77,6 +79,8 @@ struct iommu_domain_geometry {
>    *				  certain optimizations for these domains
>    *	IOMMU_DOMAIN_DMA_FQ	- As above, but definitely using batched TLB
>    *				  invalidation.
> + *	IOMMU_DOMAIN_SVA	- DMA addresses are shared process address
> + *				  spaces represented by mm_struct's.
>    */
>   #define IOMMU_DOMAIN_BLOCKED	(0U)
>   #define IOMMU_DOMAIN_IDENTITY	(__IOMMU_DOMAIN_PT)
> @@ -86,15 +90,23 @@ struct iommu_domain_geometry {
>   #define IOMMU_DOMAIN_DMA_FQ	(__IOMMU_DOMAIN_PAGING |	\
>   				 __IOMMU_DOMAIN_DMA_API |	\
>   				 __IOMMU_DOMAIN_DMA_FQ)
> +#define IOMMU_DOMAIN_SVA	(__IOMMU_DOMAIN_SVA)
>   
>   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_fault_handler_t handler;
> +			void *handler_token;
> +		};
> +		struct {	/* IOMMU_DOMAIN_SVA */
> +			struct mm_struct *mm;
> +		};
> +	};
>   };
>   
>   static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
> @@ -685,6 +697,8 @@ int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner);
>   void iommu_group_release_dma_owner(struct iommu_group *group);
>   bool iommu_group_dma_owner_claimed(struct iommu_group *group);
>   
> +struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
> +					    struct mm_struct *mm);
>   int iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev,
>   			      ioasid_t pasid);
>   void iommu_detach_device_pasid(struct iommu_domain *domain, struct device *dev,
> @@ -1063,6 +1077,12 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
>   	return false;
>   }
>   
> +static inline struct iommu_domain *
> +iommu_sva_domain_alloc(struct device *dev, struct mm_struct *mm)
> +{
> +	return NULL;
> +}
> +
>   static inline int iommu_attach_device_pasid(struct iommu_domain *domain,
>   					    struct device *dev, ioasid_t pasid)
>   {
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index be48b09371f4..10479c5e4d23 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -27,6 +27,7 @@
>   #include <linux/module.h>
>   #include <linux/cc_platform.h>
>   #include <trace/events/iommu.h>
> +#include <linux/sched/mm.h>
>   
>   static struct kset *iommu_group_kset;
>   static DEFINE_IDA(iommu_group_ida);
> @@ -1957,6 +1958,8 @@ EXPORT_SYMBOL_GPL(iommu_domain_alloc);
>   
>   void iommu_domain_free(struct iommu_domain *domain)
>   {
> +	if (domain->type == IOMMU_DOMAIN_SVA)
> +		mmdrop(domain->mm);
>   	iommu_put_dma_cookie(domain);
>   	domain->ops->free(domain);
>   }
> @@ -3274,6 +3277,23 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group)
>   }
>   EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);
>   
> +struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
> +					    struct mm_struct *mm)
> +{
> +	const struct iommu_ops *ops = dev_iommu_ops(dev);
> +	struct iommu_domain *domain;
> +
> +	domain = ops->domain_alloc(IOMMU_DOMAIN_SVA);
> +	if (!domain)
> +		return NULL;
> +
> +	domain->type = IOMMU_DOMAIN_SVA;
> +	mmgrab(mm);
> +	domain->mm = mm;
> +
> +	return domain;
> +}
> +
>   static bool iommu_group_immutable_singleton(struct iommu_group *group,
>   					    struct device *dev)
>   {

-- 
Regards,
Yi Liu