Messages in this thread |  | | Date | Fri, 10 Jun 2022 15:16:18 +0800 | Subject | Re: [PATCH v8 04/11] iommu: Add sva iommu_domain support | From | Baolu Lu <> |
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On 2022/6/10 04:25, Raj, Ashok wrote: > Hi Baolu
Hi Ashok,
> > some minor nits.
Thanks for your comments.
> > On Tue, Jun 07, 2022 at 09:49:35AM +0800, 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 SVA should provide the 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. >> - Add helpers to attach 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_attach/detach_device_pasid() can be used for other purposes, >> such as kernel DMA with pasid, mediation device, etc. >> >> 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> >> --- >> include/linux/iommu.h | 45 ++++++++++++++++++++- >> drivers/iommu/iommu.c | 93 +++++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 136 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h >> index 3fbad42c0bf8..9173c5741447 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 */ > > s/from CPU/with CPU
Sure.
> >> +#define __IOMMU_DOMAIN_HOST_VA (1U << 5) /* Host CPU virtual address */ > > Do you mean general CPU VA? or Host CPU VA, I'm reading the latter as 2nd > stage?
Host CPU VA. In the near future, we will add another flag _GUEST_VA, so that the shared page table types are distiguished.
> >> + >> /* >> * This are the possible domain-types >> * >> @@ -86,15 +89,24 @@ 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) > > Doesn't shared automatically mean CPU VA? Do we need another flag?
Yes. Shared means CPU VA, but there're many types. Besides above two, we also see the shared KVM/EPT.
> >> >> 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_DOMAIN_DMA */ >> + 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) >> @@ -262,6 +274,8 @@ 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 +296,10 @@ 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); >> @@ -679,6 +697,12 @@ 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, >> + ioasid_t pasid); >> #else /* CONFIG_IOMMU_API */ >> >> struct iommu_ops {}; >> @@ -1052,6 +1076,23 @@ 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) >> +{ >> + return -ENODEV; >> +} >> + >> +static inline void iommu_detach_device_pasid(struct iommu_domain *domain, >> + struct device *dev, ioasid_t pasid) >> +{ >> +} >> #endif /* CONFIG_IOMMU_API */ >> >> /** >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index d1ec855b1f72..e92391dcce33 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); >> @@ -39,6 +40,7 @@ struct iommu_group { >> struct kobject kobj; >> struct kobject *devices_kobj; >> struct list_head devices; >> + struct xarray pasid_array; >> struct mutex mutex; >> void *iommu_data; >> void (*iommu_data_release)(void *iommu_data); >> @@ -666,6 +668,7 @@ struct iommu_group *iommu_group_alloc(void) >> mutex_init(&group->mutex); >> INIT_LIST_HEAD(&group->devices); >> INIT_LIST_HEAD(&group->entry); >> + xa_init(&group->pasid_array); >> >> ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL); >> if (ret < 0) { >> @@ -1961,6 +1964,8 @@ 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); >> } >> @@ -3277,3 +3282,91 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group) >> return user; >> } >> 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) >> +{ >> + int count; >> + >> + mutex_lock(&group->mutex); >> + count = iommu_group_device_count(group); >> + mutex_unlock(&group->mutex); >> + >> + if (count != 1) >> + return false; >> + >> + /* >> + * The PCI device could be considered to be fully isolated if all >> + * devices on the path from the device to the host-PCI bridge are >> + * protected from peer-to-peer DMA by ACS. >> + */ >> + if (dev_is_pci(dev)) >> + return pci_acs_path_enabled(to_pci_dev(dev), NULL, >> + REQ_ACS_FLAGS); > > Does this comprehend RCiEP devices? Since they are optional even if ACS is > lacking.
Yes. It's already been covered by pci_acs_enabled().
/** * pci_acs_enabled - test ACS against required flags for a given device * @pdev: device to test * @acs_flags: required PCI ACS flags * * Return true if the device supports the provided flags. Automatically * filters out flags that are not implemented on multifunction devices. * * Note that this interface checks the effective ACS capabilities of the * device rather than the actual capabilities. For instance, most single * function endpoints are not required to support ACS because they have no * opportunity for peer-to-peer access. We therefore return 'true' * regardless of whether the device exposes an ACS capability. This makes * it much easier for callers of this function to ignore the actual type * or topology of the device when testing ACS support. */ bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags)
> >> + >> + /* >> + * Otherwise, the device came from DT/ACPI, assume it is static and >> + * then singleton can know from the device count in the group. >> + */ >> + return true; >> +} >> + >> +int iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev, >> + ioasid_t pasid) >> +{ >> + struct iommu_group *group; >> + int ret = -EBUSY; >> + void *curr; >> + >> + if (!domain->ops->set_dev_pasid) >> + return -EOPNOTSUPP; >> + >> + group = iommu_group_get(dev); >> + if (!group || !iommu_group_immutable_singleton(group, dev)) { >> + iommu_group_put(group); >> + return -EINVAL; >> + } >> + >> + mutex_lock(&group->mutex); >> + curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL); >> + if (curr) >> + goto out_unlock; >> + ret = domain->ops->set_dev_pasid(domain, dev, pasid); >> + if (ret) >> + xa_erase(&group->pasid_array, pasid); >> +out_unlock: >> + mutex_unlock(&group->mutex); >> + iommu_group_put(group); >> + >> + return ret; >> +} >> + >> +void iommu_detach_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); >> + >> + iommu_group_put(group); >> +} >> -- >> 2.25.1 >>
Best regards, baolu
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