diff options
Diffstat (limited to 'include/linux/hmm.h')
| -rw-r--r-- | include/linux/hmm.h | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 5d83fec6dfdd..76310726ee9c 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -72,6 +72,7 @@ #if IS_ENABLED(CONFIG_HMM) +struct hmm; /* * hmm_pfn_t - HMM uses its own pfn type to keep several flags per page @@ -134,6 +135,115 @@ static inline hmm_pfn_t hmm_pfn_t_from_pfn(unsigned long pfn) } +#if IS_ENABLED(CONFIG_HMM_MIRROR) +/* + * Mirroring: how to synchronize device page table with CPU page table. + * + * A device driver that is participating in HMM mirroring must always + * synchronize with CPU page table updates. For this, device drivers can either + * directly use mmu_notifier APIs or they can use the hmm_mirror API. Device + * drivers can decide to register one mirror per device per process, or just + * one mirror per process for a group of devices. The pattern is: + * + * int device_bind_address_space(..., struct mm_struct *mm, ...) + * { + * struct device_address_space *das; + * + * // Device driver specific initialization, and allocation of das + * // which contains an hmm_mirror struct as one of its fields. + * ... + * + * ret = hmm_mirror_register(&das->mirror, mm, &device_mirror_ops); + * if (ret) { + * // Cleanup on error + * return ret; + * } + * + * // Other device driver specific initialization + * ... + * } + * + * Once an hmm_mirror is registered for an address space, the device driver + * will get callbacks through sync_cpu_device_pagetables() operation (see + * hmm_mirror_ops struct). + * + * Device driver must not free the struct containing the hmm_mirror struct + * before calling hmm_mirror_unregister(). The expected usage is to do that when + * the device driver is unbinding from an address space. + * + * + * void device_unbind_address_space(struct device_address_space *das) + * { + * // Device driver specific cleanup + * ... + * + * hmm_mirror_unregister(&das->mirror); + * + * // Other device driver specific cleanup, and now das can be freed + * ... + * } + */ + +struct hmm_mirror; + +/* + * enum hmm_update_type - type of update + * @HMM_UPDATE_INVALIDATE: invalidate range (no indication as to why) + */ +enum hmm_update_type { + HMM_UPDATE_INVALIDATE, +}; + +/* + * struct hmm_mirror_ops - HMM mirror device operations callback + * + * @update: callback to update range on a device + */ +struct hmm_mirror_ops { + /* sync_cpu_device_pagetables() - synchronize page tables + * + * @mirror: pointer to struct hmm_mirror + * @update_type: type of update that occurred to the CPU page table + * @start: virtual start address of the range to update + * @end: virtual end address of the range to update + * + * This callback ultimately originates from mmu_notifiers when the CPU + * page table is updated. The device driver must update its page table + * in response to this callback. The update argument tells what action + * to perform. + * + * The device driver must not return from this callback until the device + * page tables are completely updated (TLBs flushed, etc); this is a + * synchronous call. + */ + void (*sync_cpu_device_pagetables)(struct hmm_mirror *mirror, + enum hmm_update_type update_type, + unsigned long start, + unsigned long end); +}; + +/* + * struct hmm_mirror - mirror struct for a device driver + * + * @hmm: pointer to struct hmm (which is unique per mm_struct) + * @ops: device driver callback for HMM mirror operations + * @list: for list of mirrors of a given mm + * + * Each address space (mm_struct) being mirrored by a device must register one + * instance of an hmm_mirror struct with HMM. HMM will track the list of all + * mirrors for each mm_struct. + */ +struct hmm_mirror { + struct hmm *hmm; + const struct hmm_mirror_ops *ops; + struct list_head list; +}; + +int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm); +void hmm_mirror_unregister(struct hmm_mirror *mirror); +#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */ + + /* Below are for HMM internal use only! Not to be used by device driver! */ void hmm_mm_destroy(struct mm_struct *mm); |