linux-kernel - [PATCH v6 04/12] iommu/sva: Basic data structures for SVA

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Date:   Tue, 10 May 2022 14:17:30 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>, Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Vinod Koul <vkoul@...nel.org>
Cc:     Eric Auger <eric.auger@...hat.com>, Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: [PATCH v6 04/12] iommu/sva: Basic data structures for SVA

Use below data structures for SVA implementation in the IOMMU core:

- struct iommu_domain (IOMMU_DOMAIN_SVA type)
  Represent a hardware pagetable that the IOMMU hardware could use for
  SVA translation. Multiple iommu domains could be bound with an SVA mm
  and each grabs a mm_count of the mm in order to make sure mm could
  only be freed after all domains have been unbound. A new mm field is
  added to struct iommu_domain and a helper is added to retrieve mm from
  a domain pointer.

- struct iommu_sva (existing)
  Represent a bond relationship between an SVA ioas and an iommu domain.
  If a bond already exists, it's reused and a reference is taken.

- struct dev_iommu::sva_bonds
  A pasid-indexed xarray to track the bonds happened on the device.

Suggested-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 include/linux/iommu.h | 13 +++++++++++++
 drivers/iommu/iommu.c |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ab36244d4e94..2921e634491e 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -64,6 +64,9 @@ 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_SHARED	(1U << 4)  /* Page table shared from CPU  */
+#define __IOMMU_DOMAIN_HOST_VA	(1U << 5)  /* Host CPU virtual address */
+
 /*
  * This are the possible domain-types
  *
@@ -86,6 +89,8 @@ 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_SHARED |	\
+				 __IOMMU_DOMAIN_HOST_VA)
 
 struct iommu_domain {
 	unsigned type;
@@ -95,6 +100,9 @@ struct iommu_domain {
 	void *handler_token;
 	struct iommu_domain_geometry geometry;
 	struct iommu_dma_cookie *iova_cookie;
+#ifdef CONFIG_IOMMU_SVA
+	struct mm_struct *mm;
+#endif
 };
 
 static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
@@ -380,6 +388,9 @@ struct dev_iommu {
 	struct iommu_device		*iommu_dev;
 	void				*priv;
 	unsigned int			pasid_bits;
+#ifdef CONFIG_IOMMU_SVA
+	struct xarray			sva_bonds;
+#endif
 };
 
 int iommu_device_register(struct iommu_device *iommu,
@@ -629,6 +640,8 @@ struct iommu_fwspec {
  */
 struct iommu_sva {
 	struct device			*dev;
+	struct iommu_domain		*domain;
+	refcount_t			users;
 };
 
 int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 16e8db2d86fc..1abff5fc9554 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -202,6 +202,9 @@ static struct dev_iommu *dev_iommu_get(struct device *dev)
 		return NULL;
 
 	mutex_init(&param->lock);
+#ifdef CONFIG_IOMMU_SVA
+	xa_init(&param->sva_bonds);
+#endif
 	dev->iommu = param;
 	return param;
 }
-- 
2.25.1