mm/hmm: remove the page_shift member from struct hmm_range

All users pass PAGE_SIZE here, and if we wanted to support single entries
for huge pages we should really just add a HMM_FAULT_HUGEPAGE flag instead
that uses the huge page size instead of having the caller calculate that
size once, just for the hmm code to verify it.

Link: https://lore.kernel.org/r/20190806160554.14046-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -818,7 +818,6 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
 				0 : range->flags[HMM_PFN_WRITE];
 	range->pfn_flags_mask = 0;
 	range->pfns = pfns;
-	range->page_shift = PAGE_SHIFT;
 	range->start = start;
 	range->end = start + ttm->num_pages * PAGE_SIZE;
 

drivers/gpu/drm/nouveau/nouveau_svm.c

@@ -680,7 +680,6 @@ nouveau_svm_fault(struct nvif_notify *notify)
 			 args.i.p.addr + args.i.p.size, fn - fi);
 
 		/* Have HMM fault pages within the fault window to the GPU. */
-		range.page_shift = PAGE_SHIFT;
 		range.start = args.i.p.addr;
 		range.end = args.i.p.addr + args.i.p.size;
 		range.pfns = args.phys;

include/linux/hmm.h

@@ -158,7 +158,6 @@ enum hmm_pfn_value_e {
  * @values: pfn value for some special case (none, special, error, ...)
  * @default_flags: default flags for the range (write, read, ... see hmm doc)
  * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
- * @page_shift: device virtual address shift value (should be >= PAGE_SHIFT)
  * @pfn_shifts: pfn shift value (should be <= PAGE_SHIFT)
  * @valid: pfns array did not change since it has been fill by an HMM function
  */
@@ -172,31 +171,10 @@ struct hmm_range {
 	const uint64_t		*values;
 	uint64_t		default_flags;
 	uint64_t		pfn_flags_mask;
-	uint8_t			page_shift;
 	uint8_t			pfn_shift;
 	bool			valid;
 };
 
-/*
- * hmm_range_page_shift() - return the page shift for the range
- * @range: range being queried
- * Return: page shift (page size = 1 << page shift) for the range
- */
-static inline unsigned hmm_range_page_shift(const struct hmm_range *range)
-{
-	return range->page_shift;
-}
-
-/*
- * hmm_range_page_size() - return the page size for the range
- * @range: range being queried
- * Return: page size for the range in bytes
- */
-static inline unsigned long hmm_range_page_size(const struct hmm_range *range)
-{
-	return 1UL << hmm_range_page_shift(range);
-}
-
 /*
  * hmm_range_wait_until_valid() - wait for range to be valid
  * @range: range affected by invalidation to wait on

mm/hmm.c

@@ -345,13 +345,12 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
 	struct hmm_vma_walk *hmm_vma_walk = walk->private;
 	struct hmm_range *range = hmm_vma_walk->range;
 	uint64_t *pfns = range->pfns;
-	unsigned long i, page_size;
+	unsigned long i;
 
 	hmm_vma_walk->last = addr;
-	page_size = hmm_range_page_size(range);
+	i = (addr - range->start) >> PAGE_SHIFT;
-	i = (addr - range->start) >> range->page_shift;
 
-	for (; addr < end; addr += page_size, i++) {
+	for (; addr < end; addr += PAGE_SIZE, i++) {
 		pfns[i] = range->values[HMM_PFN_NONE];
 		if (fault || write_fault) {
 			int ret;
@@ -779,7 +778,7 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
 				      struct mm_walk *walk)
 {
 #ifdef CONFIG_HUGETLB_PAGE
-	unsigned long addr = start, i, pfn, mask, size, pfn_inc;
+	unsigned long addr = start, i, pfn, mask;
 	struct hmm_vma_walk *hmm_vma_walk = walk->private;
 	struct hmm_range *range = hmm_vma_walk->range;
 	struct vm_area_struct *vma = walk->vma;
@@ -790,24 +789,12 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
 	pte_t entry;
 	int ret = 0;
 
-	size = huge_page_size(h);
+	mask = huge_page_size(h) - 1;
-	mask = size - 1;
-	if (range->page_shift != PAGE_SHIFT) {
-		/* Make sure we are looking at a full page. */
-		if (start & mask)
-			return -EINVAL;
-		if (end < (start + size))
-			return -EINVAL;
-		pfn_inc = size >> PAGE_SHIFT;
-	} else {
-		pfn_inc = 1;
-		size = PAGE_SIZE;
-	}
 
 	ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte);
 	entry = huge_ptep_get(pte);
 
-	i = (start - range->start) >> range->page_shift;
+	i = (start - range->start) >> PAGE_SHIFT;
 	orig_pfn = range->pfns[i];
 	range->pfns[i] = range->values[HMM_PFN_NONE];
 	cpu_flags = pte_to_hmm_pfn_flags(range, entry);
@@ -819,8 +806,8 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
 		goto unlock;
 	}
 
-	pfn = pte_pfn(entry) + ((start & mask) >> range->page_shift);
+	pfn = pte_pfn(entry) + ((start & mask) >> PAGE_SHIFT);
-	for (; addr < end; addr += size, i++, pfn += pfn_inc)
+	for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
 		range->pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
 				 cpu_flags;
 	hmm_vma_walk->last = end;
@@ -857,14 +844,13 @@ static void hmm_pfns_clear(struct hmm_range *range,
  */
 int hmm_range_register(struct hmm_range *range, struct hmm_mirror *mirror)
 {
-	unsigned long mask = ((1UL << range->page_shift) - 1UL);
 	struct hmm *hmm = mirror->hmm;
 	unsigned long flags;
 
 	range->valid = false;
 	range->hmm = NULL;
 
-	if ((range->start & mask) || (range->end & mask))
+	if ((range->start & (PAGE_SIZE - 1)) || (range->end & (PAGE_SIZE - 1)))
 		return -EINVAL;
 	if (range->start >= range->end)
 		return -EINVAL;
@@ -971,16 +957,6 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags)
 		if (vma == NULL || (vma->vm_flags & device_vma))
 			return -EFAULT;
 
-		if (is_vm_hugetlb_page(vma)) {
-			if (huge_page_shift(hstate_vma(vma)) !=
-			    range->page_shift &&
-			    range->page_shift != PAGE_SHIFT)
-				return -EINVAL;
-		} else {
-			if (range->page_shift != PAGE_SHIFT)
-				return -EINVAL;
-		}
-
 		if (!(vma->vm_flags & VM_READ)) {
 			/*
 			 * If vma do not allow read access, then assume that it