diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/hmm.h | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 61a6535fe438..16f916b437cc 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -72,6 +72,11 @@ #if IS_ENABLED(CONFIG_HMM) +#include <linux/migrate.h> +#include <linux/memremap.h> +#include <linux/completion.h> + + struct hmm; /* @@ -322,6 +327,156 @@ int hmm_vma_fault(struct vm_area_struct *vma, #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */ +#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) +struct hmm_devmem; + +struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma, + unsigned long addr); + +/* + * struct hmm_devmem_ops - callback for ZONE_DEVICE memory events + * + * @free: call when refcount on page reach 1 and thus is no longer use + * @fault: call when there is a page fault to unaddressable memory + * + * Both callback happens from page_free() and page_fault() callback of struct + * dev_pagemap respectively. See include/linux/memremap.h for more details on + * those. + * + * The hmm_devmem_ops callback are just here to provide a coherent and + * uniq API to device driver and device driver should not register their + * own page_free() or page_fault() but rely on the hmm_devmem_ops call- + * back. + */ +struct hmm_devmem_ops { + /* + * free() - free a device page + * @devmem: device memory structure (see struct hmm_devmem) + * @page: pointer to struct page being freed + * + * Call back occurs whenever a device page refcount reach 1 which + * means that no one is holding any reference on the page anymore + * (ZONE_DEVICE page have an elevated refcount of 1 as default so + * that they are not release to the general page allocator). + * + * Note that callback has exclusive ownership of the page (as no + * one is holding any reference). + */ + void (*free)(struct hmm_devmem *devmem, struct page *page); + /* + * fault() - CPU page fault or get user page (GUP) + * @devmem: device memory structure (see struct hmm_devmem) + * @vma: virtual memory area containing the virtual address + * @addr: virtual address that faulted or for which there is a GUP + * @page: pointer to struct page backing virtual address (unreliable) + * @flags: FAULT_FLAG_* (see include/linux/mm.h) + * @pmdp: page middle directory + * Returns: VM_FAULT_MINOR/MAJOR on success or one of VM_FAULT_ERROR + * on error + * + * The callback occurs whenever there is a CPU page fault or GUP on a + * virtual address. This means that the device driver must migrate the + * page back to regular memory (CPU accessible). + * + * The device driver is free to migrate more than one page from the + * fault() callback as an optimization. However if device decide to + * migrate more than one page it must always priotirize the faulting + * address over the others. + * + * The struct page pointer is only given as an hint to allow quick + * lookup of internal device driver data. A concurrent migration + * might have already free that page and the virtual address might + * not longer be back by it. So it should not be modified by the + * callback. + * + * Note that mmap semaphore is held in read mode at least when this + * callback occurs, hence the vma is valid upon callback entry. + */ + int (*fault)(struct hmm_devmem *devmem, + struct vm_area_struct *vma, + unsigned long addr, + const struct page *page, + unsigned int flags, + pmd_t *pmdp); +}; + +/* + * struct hmm_devmem - track device memory + * + * @completion: completion object for device memory + * @pfn_first: first pfn for this resource (set by hmm_devmem_add()) + * @pfn_last: last pfn for this resource (set by hmm_devmem_add()) + * @resource: IO resource reserved for this chunk of memory + * @pagemap: device page map for that chunk + * @device: device to bind resource to + * @ops: memory operations callback + * @ref: per CPU refcount + * + * This an helper structure for device drivers that do not wish to implement + * the gory details related to hotplugging new memoy and allocating struct + * pages. + * + * Device drivers can directly use ZONE_DEVICE memory on their own if they + * wish to do so. + */ +struct hmm_devmem { + struct completion completion; + unsigned long pfn_first; + unsigned long pfn_last; + struct resource *resource; + struct device *device; + struct dev_pagemap pagemap; + const struct hmm_devmem_ops *ops; + struct percpu_ref ref; +}; + +/* + * To add (hotplug) device memory, HMM assumes that there is no real resource + * that reserves a range in the physical address space (this is intended to be + * use by unaddressable device memory). It will reserve a physical range big + * enough and allocate struct page for it. + * + * The device driver can wrap the hmm_devmem struct inside a private device + * driver struct. The device driver must call hmm_devmem_remove() before the + * device goes away and before freeing the hmm_devmem struct memory. + */ +struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, + struct device *device, + unsigned long size); +void hmm_devmem_remove(struct hmm_devmem *devmem); + +/* + * hmm_devmem_page_set_drvdata - set per-page driver data field + * + * @page: pointer to struct page + * @data: driver data value to set + * + * Because page can not be on lru we have an unsigned long that driver can use + * to store a per page field. This just a simple helper to do that. + */ +static inline void hmm_devmem_page_set_drvdata(struct page *page, + unsigned long data) +{ + unsigned long *drvdata = (unsigned long *)&page->pgmap; + + drvdata[1] = data; +} + +/* + * hmm_devmem_page_get_drvdata - get per page driver data field + * + * @page: pointer to struct page + * Return: driver data value + */ +static inline unsigned long hmm_devmem_page_get_drvdata(struct page *page) +{ + unsigned long *drvdata = (unsigned long *)&page->pgmap; + + return drvdata[1]; +} +#endif /* IS_ENABLED(CONFIG_DEVICE_PRIVATE) */ + + /* Below are for HMM internal use only! Not to be used by device driver! */ void hmm_mm_destroy(struct mm_struct *mm); |