Messages in this thread | | | Date | Tue, 3 May 2022 19:09:22 +0100 | From | Jean-Philippe Brucker <> | Subject | Re: [PATCH v5 04/12] iommu/sva: Basic data structures for SVA |
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On Mon, May 02, 2022 at 09:48:34AM +0800, Lu Baolu wrote: > Use below data structures for SVA implementation in the IOMMU core: > > - struct iommu_sva_ioas > Represent the I/O address space shared with an application CPU address > space. This structure has a 1:1 relationship with an mm_struct. It > grabs a "mm->mm_count" refcount during creation and drop it on release.
Do we actually need this structure? At the moment it only keeps track of bonds, which we can move to struct dev_iommu. Replacing it by a mm pointer in struct iommu_domain simplifies the driver and seems to work
Thanks, Jean
> > - 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 ioas > and each grabs a refcount from ioas in order to make sure ioas could > only be freed after all domains have been unbound. > > - struct iommu_sva > 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. > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > --- > include/linux/iommu.h | 14 +++++++++++++- > drivers/iommu/iommu-sva-lib.h | 1 + > drivers/iommu/iommu-sva-lib.c | 18 ++++++++++++++++++ > 3 files changed, 32 insertions(+), 1 deletion(-) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index ab36244d4e94..f582f434c513 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -42,6 +42,7 @@ struct notifier_block; > struct iommu_sva; > struct iommu_fault_event; > struct iommu_dma_cookie; > +struct iommu_sva_ioas; > > /* iommu fault flags */ > #define IOMMU_FAULT_READ 0x0 > @@ -64,6 +65,9 @@ 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 +90,8 @@ 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 +101,7 @@ struct iommu_domain { > void *handler_token; > struct iommu_domain_geometry geometry; > struct iommu_dma_cookie *iova_cookie; > + struct iommu_sva_ioas *sva_ioas; > }; > > static inline bool iommu_is_dma_domain(struct iommu_domain *domain) > @@ -628,7 +635,12 @@ struct iommu_fwspec { > * struct iommu_sva - handle to a device-mm bond > */ > struct iommu_sva { > - struct device *dev; > + struct device *dev; > + struct iommu_sva_ioas *sva_ioas; > + struct iommu_domain *domain; > + /* Link to sva ioas's bonds list */ > + struct list_head node; > + refcount_t users; > }; > > int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode, > diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h > index 8909ea1094e3..9c5e108e2c8a 100644 > --- a/drivers/iommu/iommu-sva-lib.h > +++ b/drivers/iommu/iommu-sva-lib.h > @@ -10,6 +10,7 @@ > > int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max); > struct mm_struct *iommu_sva_find(ioasid_t pasid); > +struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain); > > /* I/O Page fault */ > struct device; > diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c > index 106506143896..d524a402be3b 100644 > --- a/drivers/iommu/iommu-sva-lib.c > +++ b/drivers/iommu/iommu-sva-lib.c > @@ -3,6 +3,8 @@ > * Helpers for IOMMU drivers implementing SVA > */ > #include <linux/mutex.h> > +#include <linux/iommu.h> > +#include <linux/slab.h> > #include <linux/sched/mm.h> > > #include "iommu-sva-lib.h" > @@ -10,6 +12,22 @@ > static DEFINE_MUTEX(iommu_sva_lock); > static DECLARE_IOASID_SET(iommu_sva_pasid); > > +struct iommu_sva_ioas { > + struct mm_struct *mm; > + ioasid_t pasid; > + > + /* Counter of domains attached to this ioas. */ > + refcount_t users; > + > + /* All bindings are linked here. */ > + struct list_head bonds; > +}; > + > +struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain) > +{ > + return domain->sva_ioas->mm; > +} > + > /** > * iommu_sva_alloc_pasid - Allocate a PASID for the mm > * @mm: the mm > -- > 2.25.1 >
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