by Jason Gunthorpe

[permalink] [raw]

Subject: Re: [PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support

On Thu, May 19, 2022 at 03:20:40PM +0800, Lu Baolu wrote:
> The iommu_sva_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:
>
> - Add a new struct iommu_sva_domain and new IOMMU_DOMAIN_SVA domain
> type.
> - Add a new domain ops pointer in iommu_ops. The IOMMU drivers that
> support SVA should provide the callbacks.
> - Add helpers to allocate and free an SVA domain.
> - Add helpers to set an SVA domain to a device and the reverse
> operation.
>
> Some buses, like PCI, route packets without considering the PASID value.
> Thus a DMA target address with PASID might be treated as P2P if the
> address falls into the MMIO BAR of other devices in the group. To make
> things simple, the attach/detach interfaces only apply to devices
> belonging to the singleton groups, and the singleton is immutable in
> fabric i.e. not affected by hotplug.
>
> The iommu_set/block_device_pasid() can be used for other purposes,
> such as kernel DMA with pasid, mediation device, etc. Hence, it is put
> in the iommu.c.
>
> Suggested-by: Jean-Philippe Brucker <[email protected]>
> Suggested-by: Jason Gunthorpe <[email protected]>
> Signed-off-by: Lu Baolu <[email protected]>
> include/linux/iommu.h | 51 +++++++++++++++++++++++++
> drivers/iommu/iommu-sva-lib.h | 15 ++++++++
> drivers/iommu/iommu-sva-lib.c | 48 +++++++++++++++++++++++
> drivers/iommu/iommu.c | 71 +++++++++++++++++++++++++++++++++++
> 4 files changed, 185 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 0c358b7c583b..e8cf82d46ce1 100644
> +++ 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;
> @@ -254,6 +259,7 @@ struct iommu_ops {
> int (*def_domain_type)(struct device *dev);
>
> const struct iommu_domain_ops *default_domain_ops;
> + const struct iommu_domain_ops *sva_domain_ops;
> unsigned long pgsize_bitmap;
> struct module *owner;
> };
> @@ -262,6 +268,8 @@ struct iommu_ops {
> * struct iommu_domain_ops - domain specific operations
> * @attach_dev: attach an iommu domain to a device
> * @detach_dev: detach an iommu domain from a device
> + * @set_dev_pasid: set an iommu domain to a pasid of device
> + * @block_dev_pasid: block pasid of device from using iommu domain
> * @map: map a physically contiguous memory region to an iommu domain
> * @map_pages: map a physically contiguous set of pages of the same size to
> * an iommu domain.
> @@ -282,6 +290,10 @@ struct iommu_ops {
> struct iommu_domain_ops {
> int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
> void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
> + int (*set_dev_pasid)(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
> + void (*block_dev_pasid)(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
>
> int (*map)(struct iommu_domain *domain, unsigned long iova,
> phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
> @@ -677,6 +689,10 @@ 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);
>
> +int iommu_set_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
> +void iommu_block_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
> #else /* CONFIG_IOMMU_API */
>
> struct iommu_ops {};
> @@ -1050,6 +1066,17 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
> {
> return false;
> }
> +
> +static inline int iommu_set_device_pasid(struct iommu_domain *domain,
> + struct device *dev, ioasid_t pasid)
> +{
> + return -ENODEV;
> +}
> +
> +static inline void iommu_block_device_pasid(struct iommu_domain *domain,
> + struct device *dev, ioasid_t pasid)
> +{
> +}
> #endif /* CONFIG_IOMMU_API */
>
> /**
> @@ -1075,4 +1102,28 @@ void iommu_debugfs_setup(void);
> static inline void iommu_debugfs_setup(void) {}
> #endif
>
> +#ifdef CONFIG_IOMMU_SVA
> +struct iommu_domain *
> +iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm);
> +void iommu_sva_free_domain(struct iommu_domain *domain);
> +int iommu_sva_set_domain(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid);
> +#else /* CONFIG_IOMMU_SVA */
> +static inline struct iommu_domain *
> +iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm)
> +{
> + return ERR_PTR(-EINVAL);
> +}
> +
> +static inline void iommu_sva_free_domain(struct iommu_domain *domain)
> +{
> +}
> +
> +static inline int iommu_sva_set_domain(struct iommu_domain *domain,
> + struct device *dev, ioasid_t pasid)
> +{
> + return -EINVAL;
> +}
> +#endif /* CONFIG_IOMMU_SVA */
> +
> #endif /* __LINUX_IOMMU_H */
> diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
> index 8909ea1094e3..1be21e6b93ec 100644
> +++ b/drivers/iommu/iommu-sva-lib.h
> @@ -7,6 +7,7 @@
>
> #include <linux/ioasid.h>
> #include <linux/mm_types.h>
> +#include <linux/iommu.h>
>
> int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);
> struct mm_struct *iommu_sva_find(ioasid_t pasid);
> @@ -16,6 +17,20 @@ struct device;
> struct iommu_fault;
> struct iopf_queue;
>
> +struct iommu_sva_domain {
> + struct iommu_domain domain;
> + struct mm_struct *mm;
> +};
> +
> +#define to_sva_domain(d) container_of_safe(d, struct iommu_sva_domain, domain)
> +
> +static inline struct mm_struct *domain_to_mm(struct iommu_domain *domain)
> +{
> + struct iommu_sva_domain *sva_domain = to_sva_domain(domain);
> +
> + return sva_domain->mm;
> +}
> +
> #ifdef CONFIG_IOMMU_SVA
> int iommu_queue_iopf(struct iommu_fault *fault, void *cookie);
>
> diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
> index 106506143896..210c376f6043 100644
> +++ b/drivers/iommu/iommu-sva-lib.c
> @@ -69,3 +69,51 @@ struct mm_struct *iommu_sva_find(ioasid_t pasid)
> return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
> }
> EXPORT_SYMBOL_GPL(iommu_sva_find);
> +
> +/*
> + * IOMMU SVA driver-oriented interfaces
> + */
> +struct iommu_domain *
> +iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm)

This should return the proper type

> +{
> + struct iommu_sva_domain *sva_domain;
> + struct iommu_domain *domain;
> +
> + if (!bus->iommu_ops || !bus->iommu_ops->sva_domain_ops)
> + return ERR_PTR(-ENODEV);
> +
> + sva_domain = kzalloc(sizeof(*sva_domain), GFP_KERNEL);
> + if (!sva_domain)
> + return ERR_PTR(-ENOMEM);
> +
> + mmgrab(mm);
> + sva_domain->mm = mm;
> +
> + domain = &sva_domain->domain;
> + domain->type = IOMMU_DOMAIN_SVA;
> + domain->ops = bus->iommu_ops->sva_domain_ops;
> +
> + return domain;
> +}
> +
> +void iommu_sva_free_domain(struct iommu_domain *domain)
> +{
> + struct iommu_sva_domain *sva_domain = to_sva_domain(domain);
> +
> + mmdrop(sva_domain->mm);
> + kfree(sva_domain);
> +}

No callback to the driver?

> +int iommu_sva_set_domain(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid)
> +{

Why does this function exist? Just call iommu_set_device_pasid()

> +int iommu_set_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid)
> +{

Here you can continue to use attach/detach language as at this API
level we expect strict pairing..

> +void iommu_block_device_pasid(struct iommu_domain *domain, struct device *dev,
> + ioasid_t pasid)
> +{
> + struct iommu_group *group = iommu_group_get(dev);
> +
> + mutex_lock(&group->mutex);
> + domain->ops->block_dev_pasid(domain, dev, pasid);
> + xa_erase(&group->pasid_array, pasid);
> + mutex_unlock(&group->mutex);

Should be the blocking domain.

Jason