diff options
| -rw-r--r-- | Documentation/vm/hmm.rst | 26 | ||||
| -rw-r--r-- | include/linux/hmm.h | 4 | ||||
| -rw-r--r-- | mm/hmm.c | 31 |
3 files changed, 37 insertions, 24 deletions
diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst index 44205f0b671f..d9b27bdadd1b 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -189,11 +189,7 @@ the driver callback returns. When the device driver wants to populate a range of virtual addresses, it can use either:: - int hmm_vma_get_pfns(struct vm_area_struct *vma, - struct hmm_range *range, - unsigned long start, - unsigned long end, - hmm_pfn_t *pfns); + long hmm_range_snapshot(struct hmm_range *range); int hmm_vma_fault(struct vm_area_struct *vma, struct hmm_range *range, unsigned long start, @@ -202,7 +198,7 @@ use either:: bool write, bool block); -The first one (hmm_vma_get_pfns()) will only fetch present CPU page table +The first one (hmm_range_snapshot()) will only fetch present CPU page table entries and will not trigger a page fault on missing or non-present entries. The second one does trigger a page fault on missing or read-only entry if the write parameter is true. Page faults use the generic mm page fault code path @@ -220,19 +216,33 @@ respect in order to keep things properly synchronized. The usage pattern is:: { struct hmm_range range; ... + + range.start = ...; + range.end = ...; + range.pfns = ...; + range.flags = ...; + range.values = ...; + range.pfn_shift = ...; + again: - ret = hmm_vma_get_pfns(vma, &range, start, end, pfns); - if (ret) + down_read(&mm->mmap_sem); + range.vma = ...; + ret = hmm_range_snapshot(&range); + if (ret) { + up_read(&mm->mmap_sem); return ret; + } take_lock(driver->update); if (!hmm_vma_range_done(vma, &range)) { release_lock(driver->update); + up_read(&mm->mmap_sem); goto again; } // Use pfns array content to update device page table release_lock(driver->update); + up_read(&mm->mmap_sem); return 0; } diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 716fc61fa6d4..32206b0b1bfd 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -365,11 +365,11 @@ void hmm_mirror_unregister(struct hmm_mirror *mirror); * table invalidation serializes on it. * * YOU MUST CALL hmm_vma_range_done() ONCE AND ONLY ONCE EACH TIME YOU CALL - * hmm_vma_get_pfns() WITHOUT ERROR ! + * hmm_range_snapshot() WITHOUT ERROR ! * * IF YOU DO NOT FOLLOW THE ABOVE RULE THE SNAPSHOT CONTENT MIGHT BE INVALID ! */ -int hmm_vma_get_pfns(struct hmm_range *range); +long hmm_range_snapshot(struct hmm_range *range); bool hmm_vma_range_done(struct hmm_range *range); @@ -702,23 +702,25 @@ static void hmm_pfns_special(struct hmm_range *range) } /* - * hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses - * @range: range being snapshotted - * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid - * vma permission, 0 success + * hmm_range_snapshot() - snapshot CPU page table for a range + * @range: range + * Returns: number of valid pages in range->pfns[] (from range start + * address). This may be zero. If the return value is negative, + * then one of the following values may be returned: + * + * -EINVAL invalid arguments or mm or virtual address are in an + * invalid vma (ie either hugetlbfs or device file vma). + * -EPERM For example, asking for write, when the range is + * read-only + * -EAGAIN Caller needs to retry + * -EFAULT Either no valid vma exists for this range, or it is + * illegal to access the range * * This snapshots the CPU page table for a range of virtual addresses. Snapshot * validity is tracked by range struct. See hmm_vma_range_done() for further * information. - * - * The range struct is initialized here. It tracks the CPU page table, but only - * if the function returns success (0), in which case the caller must then call - * hmm_vma_range_done() to stop CPU page table update tracking on this range. - * - * NOT CALLING hmm_vma_range_done() IF FUNCTION RETURNS 0 WILL LEAD TO SERIOUS - * MEMORY CORRUPTION ! YOU HAVE BEEN WARNED ! */ -int hmm_vma_get_pfns(struct hmm_range *range) +long hmm_range_snapshot(struct hmm_range *range) { struct vm_area_struct *vma = range->vma; struct hmm_vma_walk hmm_vma_walk; @@ -772,6 +774,7 @@ int hmm_vma_get_pfns(struct hmm_range *range) hmm_vma_walk.fault = false; hmm_vma_walk.range = range; mm_walk.private = &hmm_vma_walk; + hmm_vma_walk.last = range->start; mm_walk.vma = vma; mm_walk.mm = vma->vm_mm; @@ -788,9 +791,9 @@ int hmm_vma_get_pfns(struct hmm_range *range) * function return 0). */ range->hmm = hmm; - return 0; + return (hmm_vma_walk.last - range->start) >> PAGE_SHIFT; } -EXPORT_SYMBOL(hmm_vma_get_pfns); +EXPORT_SYMBOL(hmm_range_snapshot); /* * hmm_vma_range_done() - stop tracking change to CPU page table over a range |