#include <linux/hugetlb.h>
#include <linux/memremap.h>
#include <linux/jump_label.h>
+#include <linux/dma-mapping.h>
#include <linux/mmu_notifier.h>
#include <linux/memory_hotplug.h>
#if IS_ENABLED(CONFIG_HMM_MIRROR)
static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
-/*
- * struct hmm - HMM per mm struct
- *
- * @mm: mm struct this HMM struct is bound to
- * @lock: lock protecting ranges list
- * @ranges: list of range being snapshotted
- * @mirrors: list of mirrors for this mm
- * @mmu_notifier: mmu notifier to track updates to CPU page table
- * @mirrors_sem: read/write semaphore protecting the mirrors list
- */
-struct hmm {
- struct mm_struct *mm;
- spinlock_t lock;
- struct list_head ranges;
- struct list_head mirrors;
- struct mmu_notifier mmu_notifier;
- struct rw_semaphore mirrors_sem;
-};
+static inline struct hmm *mm_get_hmm(struct mm_struct *mm)
+{
+ struct hmm *hmm = READ_ONCE(mm->hmm);
-/*
- * hmm_register - register HMM against an mm (HMM internal)
+ if (hmm && kref_get_unless_zero(&hmm->kref))
+ return hmm;
+
+ return NULL;
+}
+
+/**
+ * hmm_get_or_create - register HMM against an mm (HMM internal)
*
* @mm: mm struct to attach to
+ * Returns: returns an HMM object, either by referencing the existing
+ * (per-process) object, or by creating a new one.
*
- * This is not intended to be used directly by device drivers. It allocates an
- * HMM struct if mm does not have one, and initializes it.
+ * This is not intended to be used directly by device drivers. If mm already
+ * has an HMM struct then it get a reference on it and returns it. Otherwise
+ * it allocates an HMM struct, initializes it, associate it with the mm and
+ * returns it.
*/
-static struct hmm *hmm_register(struct mm_struct *mm)
+static struct hmm *hmm_get_or_create(struct mm_struct *mm)
{
- struct hmm *hmm = READ_ONCE(mm->hmm);
+ struct hmm *hmm = mm_get_hmm(mm);
bool cleanup = false;
- /*
- * The hmm struct can only be freed once the mm_struct goes away,
- * hence we should always have pre-allocated an new hmm struct
- * above.
- */
if (hmm)
return hmm;
hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
if (!hmm)
return NULL;
+ init_waitqueue_head(&hmm->wq);
INIT_LIST_HEAD(&hmm->mirrors);
init_rwsem(&hmm->mirrors_sem);
hmm->mmu_notifier.ops = NULL;
INIT_LIST_HEAD(&hmm->ranges);
- spin_lock_init(&hmm->lock);
+ mutex_init(&hmm->lock);
+ kref_init(&hmm->kref);
+ hmm->notifiers = 0;
+ hmm->dead = false;
hmm->mm = mm;
spin_lock(&mm->page_table_lock);
if (__mmu_notifier_register(&hmm->mmu_notifier, mm))
goto error_mm;
- return mm->hmm;
+ return hmm;
error_mm:
spin_lock(&mm->page_table_lock);
return NULL;
}
-void hmm_mm_destroy(struct mm_struct *mm)
+static void hmm_free(struct kref *kref)
{
- kfree(mm->hmm);
-}
+ struct hmm *hmm = container_of(kref, struct hmm, kref);
+ struct mm_struct *mm = hmm->mm;
-static int hmm_invalidate_range(struct hmm *hmm, bool device,
- const struct hmm_update *update)
-{
- struct hmm_mirror *mirror;
- struct hmm_range *range;
-
- spin_lock(&hmm->lock);
- list_for_each_entry(range, &hmm->ranges, list) {
- unsigned long addr, idx, npages;
+ mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm);
- if (update->end < range->start || update->start >= range->end)
- continue;
+ spin_lock(&mm->page_table_lock);
+ if (mm->hmm == hmm)
+ mm->hmm = NULL;
+ spin_unlock(&mm->page_table_lock);
- range->valid = false;
- addr = max(update->start, range->start);
- idx = (addr - range->start) >> PAGE_SHIFT;
- npages = (min(range->end, update->end) - addr) >> PAGE_SHIFT;
- memset(&range->pfns[idx], 0, sizeof(*range->pfns) * npages);
- }
- spin_unlock(&hmm->lock);
+ kfree(hmm);
+}
- if (!device)
- return 0;
+static inline void hmm_put(struct hmm *hmm)
+{
+ kref_put(&hmm->kref, hmm_free);
+}
- down_read(&hmm->mirrors_sem);
- list_for_each_entry(mirror, &hmm->mirrors, list) {
- int ret;
+void hmm_mm_destroy(struct mm_struct *mm)
+{
+ struct hmm *hmm;
- ret = mirror->ops->sync_cpu_device_pagetables(mirror, update);
- if (!update->blockable && ret == -EAGAIN) {
- up_read(&hmm->mirrors_sem);
- return -EAGAIN;
- }
+ spin_lock(&mm->page_table_lock);
+ hmm = mm_get_hmm(mm);
+ mm->hmm = NULL;
+ if (hmm) {
+ hmm->mm = NULL;
+ hmm->dead = true;
+ spin_unlock(&mm->page_table_lock);
+ hmm_put(hmm);
+ return;
}
- up_read(&hmm->mirrors_sem);
- return 0;
+ spin_unlock(&mm->page_table_lock);
}
static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
+ struct hmm *hmm = mm_get_hmm(mm);
struct hmm_mirror *mirror;
- struct hmm *hmm = mm->hmm;
+ struct hmm_range *range;
+
+ /* Report this HMM as dying. */
+ hmm->dead = true;
+
+ /* Wake-up everyone waiting on any range. */
+ mutex_lock(&hmm->lock);
+ list_for_each_entry(range, &hmm->ranges, list) {
+ range->valid = false;
+ }
+ wake_up_all(&hmm->wq);
+ mutex_unlock(&hmm->lock);
down_write(&hmm->mirrors_sem);
mirror = list_first_entry_or_null(&hmm->mirrors, struct hmm_mirror,
struct hmm_mirror, list);
}
up_write(&hmm->mirrors_sem);
+
+ hmm_put(hmm);
}
static int hmm_invalidate_range_start(struct mmu_notifier *mn,
- const struct mmu_notifier_range *range)
+ const struct mmu_notifier_range *nrange)
{
+ struct hmm *hmm = mm_get_hmm(nrange->mm);
+ struct hmm_mirror *mirror;
struct hmm_update update;
- struct hmm *hmm = range->mm->hmm;
+ struct hmm_range *range;
+ int ret = 0;
VM_BUG_ON(!hmm);
- update.start = range->start;
- update.end = range->end;
+ update.start = nrange->start;
+ update.end = nrange->end;
update.event = HMM_UPDATE_INVALIDATE;
- update.blockable = range->blockable;
- return hmm_invalidate_range(hmm, true, &update);
+ update.blockable = mmu_notifier_range_blockable(nrange);
+
+ if (mmu_notifier_range_blockable(nrange))
+ mutex_lock(&hmm->lock);
+ else if (!mutex_trylock(&hmm->lock)) {
+ ret = -EAGAIN;
+ goto out;
+ }
+ hmm->notifiers++;
+ list_for_each_entry(range, &hmm->ranges, list) {
+ if (update.end < range->start || update.start >= range->end)
+ continue;
+
+ range->valid = false;
+ }
+ mutex_unlock(&hmm->lock);
+
+ if (mmu_notifier_range_blockable(nrange))
+ down_read(&hmm->mirrors_sem);
+ else if (!down_read_trylock(&hmm->mirrors_sem)) {
+ ret = -EAGAIN;
+ goto out;
+ }
+ list_for_each_entry(mirror, &hmm->mirrors, list) {
+ int ret;
+
+ ret = mirror->ops->sync_cpu_device_pagetables(mirror, &update);
+ if (!update.blockable && ret == -EAGAIN) {
+ up_read(&hmm->mirrors_sem);
+ ret = -EAGAIN;
+ goto out;
+ }
+ }
+ up_read(&hmm->mirrors_sem);
+
+out:
+ hmm_put(hmm);
+ return ret;
}
static void hmm_invalidate_range_end(struct mmu_notifier *mn,
- const struct mmu_notifier_range *range)
+ const struct mmu_notifier_range *nrange)
{
- struct hmm_update update;
- struct hmm *hmm = range->mm->hmm;
+ struct hmm *hmm = mm_get_hmm(nrange->mm);
VM_BUG_ON(!hmm);
- update.start = range->start;
- update.end = range->end;
- update.event = HMM_UPDATE_INVALIDATE;
- update.blockable = true;
- hmm_invalidate_range(hmm, false, &update);
+ mutex_lock(&hmm->lock);
+ hmm->notifiers--;
+ if (!hmm->notifiers) {
+ struct hmm_range *range;
+
+ list_for_each_entry(range, &hmm->ranges, list) {
+ if (range->valid)
+ continue;
+ range->valid = true;
+ }
+ wake_up_all(&hmm->wq);
+ }
+ mutex_unlock(&hmm->lock);
+
+ hmm_put(hmm);
}
static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
if (!mm || !mirror || !mirror->ops)
return -EINVAL;
-again:
- mirror->hmm = hmm_register(mm);
+ mirror->hmm = hmm_get_or_create(mm);
if (!mirror->hmm)
return -ENOMEM;
down_write(&mirror->hmm->mirrors_sem);
- if (mirror->hmm->mm == NULL) {
- /*
- * A racing hmm_mirror_unregister() is about to destroy the hmm
- * struct. Try again to allocate a new one.
- */
- up_write(&mirror->hmm->mirrors_sem);
- mirror->hmm = NULL;
- goto again;
- } else {
- list_add(&mirror->list, &mirror->hmm->mirrors);
- up_write(&mirror->hmm->mirrors_sem);
- }
+ list_add(&mirror->list, &mirror->hmm->mirrors);
+ up_write(&mirror->hmm->mirrors_sem);
return 0;
}
*/
void hmm_mirror_unregister(struct hmm_mirror *mirror)
{
- bool should_unregister = false;
- struct mm_struct *mm;
- struct hmm *hmm;
+ struct hmm *hmm = READ_ONCE(mirror->hmm);
- if (mirror->hmm == NULL)
+ if (hmm == NULL)
return;
- hmm = mirror->hmm;
down_write(&hmm->mirrors_sem);
list_del_init(&mirror->list);
- should_unregister = list_empty(&hmm->mirrors);
+ /* To protect us against double unregister ... */
mirror->hmm = NULL;
- mm = hmm->mm;
- hmm->mm = NULL;
up_write(&hmm->mirrors_sem);
- if (!should_unregister || mm == NULL)
- return;
-
- mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm);
-
- spin_lock(&mm->page_table_lock);
- if (mm->hmm == hmm)
- mm->hmm = NULL;
- spin_unlock(&mm->page_table_lock);
-
- kfree(hmm);
+ hmm_put(hmm);
}
EXPORT_SYMBOL(hmm_mirror_unregister);
struct hmm_vma_walk {
struct hmm_range *range;
+ struct dev_pagemap *pgmap;
unsigned long last;
bool fault;
bool block;
flags |= write_fault ? FAULT_FLAG_WRITE : 0;
ret = handle_mm_fault(vma, addr, flags);
if (ret & VM_FAULT_RETRY)
- return -EBUSY;
+ return -EAGAIN;
if (ret & VM_FAULT_ERROR) {
*pfn = range->values[HMM_PFN_ERROR];
return -EFAULT;
}
- return -EAGAIN;
+ return -EBUSY;
}
static int hmm_pfns_bad(unsigned long addr,
* @fault: should we fault or not ?
* @write_fault: write fault ?
* @walk: mm_walk structure
- * Returns: 0 on success, -EAGAIN after page fault, or page fault error
+ * Returns: 0 on success, -EBUSY after page fault, or page fault error
*
* This function will be called whenever pmd_none() or pte_none() returns true,
* or whenever there is no page directory covering the virtual address range.
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;
+ unsigned long i, page_size;
hmm_vma_walk->last = addr;
- i = (addr - range->start) >> PAGE_SHIFT;
- for (; addr < end; addr += PAGE_SIZE, i++) {
+ page_size = hmm_range_page_size(range);
+ i = (addr - range->start) >> range->page_shift;
+
+ for (; addr < end; addr += page_size, i++) {
pfns[i] = range->values[HMM_PFN_NONE];
if (fault || write_fault) {
int ret;
ret = hmm_vma_do_fault(walk, addr, write_fault,
&pfns[i]);
- if (ret != -EAGAIN)
+ if (ret != -EBUSY)
return ret;
}
}
- return (fault || write_fault) ? -EAGAIN : 0;
+ return (fault || write_fault) ? -EBUSY : 0;
}
static inline void hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
{
struct hmm_range *range = hmm_vma_walk->range;
- *fault = *write_fault = false;
if (!hmm_vma_walk->fault)
return;
+ /*
+ * So we not only consider the individual per page request we also
+ * consider the default flags requested for the range. The API can
+ * be use in 2 fashions. The first one where the HMM user coalesce
+ * multiple page fault into one request and set flags per pfns for
+ * of those faults. The second one where the HMM user want to pre-
+ * fault a range with specific flags. For the latter one it is a
+ * waste to have the user pre-fill the pfn arrays with a default
+ * flags value.
+ */
+ pfns = (pfns & range->pfn_flags_mask) | range->default_flags;
+
/* We aren't ask to do anything ... */
if (!(pfns & range->flags[HMM_PFN_VALID]))
return;
return;
}
+ *fault = *write_fault = false;
for (i = 0; i < npages; ++i) {
hmm_pte_need_fault(hmm_vma_walk, pfns[i], cpu_flags,
fault, write_fault);
- if ((*fault) || (*write_fault))
+ if ((*write_fault))
return;
}
}
range->flags[HMM_PFN_VALID];
}
+static inline uint64_t pud_to_hmm_pfn_flags(struct hmm_range *range, pud_t pud)
+{
+ if (!pud_present(pud))
+ return 0;
+ return pud_write(pud) ? range->flags[HMM_PFN_VALID] |
+ range->flags[HMM_PFN_WRITE] :
+ range->flags[HMM_PFN_VALID];
+}
+
static int hmm_vma_handle_pmd(struct mm_walk *walk,
unsigned long addr,
unsigned long end,
uint64_t *pfns,
pmd_t pmd)
{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
unsigned long pfn, npages, i;
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
pfn = pmd_pfn(pmd) + pte_index(addr);
- for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
- pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags;
+ for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) {
+ if (pmd_devmap(pmd)) {
+ hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
+ hmm_vma_walk->pgmap);
+ if (unlikely(!hmm_vma_walk->pgmap))
+ return -EBUSY;
+ }
+ pfns[i] = hmm_device_entry_from_pfn(range, pfn) | cpu_flags;
+ }
+ if (hmm_vma_walk->pgmap) {
+ put_dev_pagemap(hmm_vma_walk->pgmap);
+ hmm_vma_walk->pgmap = NULL;
+ }
hmm_vma_walk->last = end;
return 0;
+#else
+ /* If THP is not enabled then we should never reach that code ! */
+ return -EINVAL;
+#endif
}
static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
uint64_t orig_pfn = *pfn;
*pfn = range->values[HMM_PFN_NONE];
- cpu_flags = pte_to_hmm_pfn_flags(range, pte);
- hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
- &fault, &write_fault);
+ fault = write_fault = false;
if (pte_none(pte)) {
+ hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0,
+ &fault, &write_fault);
if (fault || write_fault)
goto fault;
return 0;
&fault, &write_fault);
if (fault || write_fault)
goto fault;
- *pfn = hmm_pfn_from_pfn(range, swp_offset(entry));
+ *pfn = hmm_device_entry_from_pfn(range,
+ swp_offset(entry));
*pfn |= cpu_flags;
return 0;
}
hmm_vma_walk->last = addr;
migration_entry_wait(vma->vm_mm,
pmdp, addr);
- return -EAGAIN;
+ return -EBUSY;
}
return 0;
}
/* Report error for everything else */
*pfn = range->values[HMM_PFN_ERROR];
return -EFAULT;
+ } else {
+ cpu_flags = pte_to_hmm_pfn_flags(range, pte);
+ hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
+ &fault, &write_fault);
}
if (fault || write_fault)
goto fault;
- *pfn = hmm_pfn_from_pfn(range, pte_pfn(pte)) | cpu_flags;
+ if (pte_devmap(pte)) {
+ hmm_vma_walk->pgmap = get_dev_pagemap(pte_pfn(pte),
+ hmm_vma_walk->pgmap);
+ if (unlikely(!hmm_vma_walk->pgmap))
+ return -EBUSY;
+ } else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) {
+ *pfn = range->values[HMM_PFN_SPECIAL];
+ return -EFAULT;
+ }
+
+ *pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags;
return 0;
fault:
+ if (hmm_vma_walk->pgmap) {
+ put_dev_pagemap(hmm_vma_walk->pgmap);
+ hmm_vma_walk->pgmap = NULL;
+ }
pte_unmap(ptep);
/* Fault any virtual address we were asked to fault */
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
if (fault || write_fault) {
hmm_vma_walk->last = addr;
pmd_migration_entry_wait(vma->vm_mm, pmdp);
- return -EAGAIN;
+ return -EBUSY;
}
return 0;
} else if (!pmd_present(pmd))
return r;
}
}
+ if (hmm_vma_walk->pgmap) {
+ /*
+ * We do put_dev_pagemap() here and not in hmm_vma_handle_pte()
+ * so that we can leverage get_dev_pagemap() optimization which
+ * will not re-take a reference on a pgmap if we already have
+ * one.
+ */
+ put_dev_pagemap(hmm_vma_walk->pgmap);
+ hmm_vma_walk->pgmap = NULL;
+ }
pte_unmap(ptep - 1);
hmm_vma_walk->last = addr;
return 0;
}
+static int hmm_vma_walk_pud(pud_t *pudp,
+ unsigned long start,
+ unsigned long end,
+ struct mm_walk *walk)
+{
+ struct hmm_vma_walk *hmm_vma_walk = walk->private;
+ struct hmm_range *range = hmm_vma_walk->range;
+ unsigned long addr = start, next;
+ pmd_t *pmdp;
+ pud_t pud;
+ int ret;
+
+again:
+ pud = READ_ONCE(*pudp);
+ if (pud_none(pud))
+ return hmm_vma_walk_hole(start, end, walk);
+
+ if (pud_huge(pud) && pud_devmap(pud)) {
+ unsigned long i, npages, pfn;
+ uint64_t *pfns, cpu_flags;
+ bool fault, write_fault;
+
+ if (!pud_present(pud))
+ return hmm_vma_walk_hole(start, end, walk);
+
+ i = (addr - range->start) >> PAGE_SHIFT;
+ npages = (end - addr) >> PAGE_SHIFT;
+ pfns = &range->pfns[i];
+
+ cpu_flags = pud_to_hmm_pfn_flags(range, pud);
+ hmm_range_need_fault(hmm_vma_walk, pfns, npages,
+ cpu_flags, &fault, &write_fault);
+ if (fault || write_fault)
+ return hmm_vma_walk_hole_(addr, end, fault,
+ write_fault, walk);
+
+#ifdef CONFIG_HUGETLB_PAGE
+ pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+ for (i = 0; i < npages; ++i, ++pfn) {
+ hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
+ hmm_vma_walk->pgmap);
+ if (unlikely(!hmm_vma_walk->pgmap))
+ return -EBUSY;
+ pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
+ cpu_flags;
+ }
+ if (hmm_vma_walk->pgmap) {
+ put_dev_pagemap(hmm_vma_walk->pgmap);
+ hmm_vma_walk->pgmap = NULL;
+ }
+ hmm_vma_walk->last = end;
+ return 0;
+#else
+ return -EINVAL;
+#endif
+ }
+
+ split_huge_pud(walk->vma, pudp, addr);
+ if (pud_none(*pudp))
+ goto again;
+
+ pmdp = pmd_offset(pudp, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ ret = hmm_vma_walk_pmd(pmdp, addr, next, walk);
+ if (ret)
+ return ret;
+ } while (pmdp++, addr = next, addr != end);
+
+ return 0;
+}
+
+static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
+ unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+#ifdef CONFIG_HUGETLB_PAGE
+ unsigned long addr = start, i, pfn, mask, size, pfn_inc;
+ struct hmm_vma_walk *hmm_vma_walk = walk->private;
+ struct hmm_range *range = hmm_vma_walk->range;
+ struct vm_area_struct *vma = walk->vma;
+ struct hstate *h = hstate_vma(vma);
+ uint64_t orig_pfn, cpu_flags;
+ bool fault, write_fault;
+ spinlock_t *ptl;
+ pte_t entry;
+ int ret = 0;
+
+ size = 1UL << huge_page_shift(h);
+ mask = size - 1;
+ if (range->page_shift != PAGE_SHIFT) {
+ /* Make sure we are looking at 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(walk->vma), walk->mm, pte);
+ entry = huge_ptep_get(pte);
+
+ i = (start - range->start) >> range->page_shift;
+ orig_pfn = range->pfns[i];
+ range->pfns[i] = range->values[HMM_PFN_NONE];
+ cpu_flags = pte_to_hmm_pfn_flags(range, entry);
+ fault = write_fault = false;
+ hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
+ &fault, &write_fault);
+ if (fault || write_fault) {
+ ret = -ENOENT;
+ goto unlock;
+ }
+
+ pfn = pte_pfn(entry) + ((start & mask) >> range->page_shift);
+ for (; addr < end; addr += size, i++, pfn += pfn_inc)
+ range->pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
+ cpu_flags;
+ hmm_vma_walk->last = end;
+
+unlock:
+ spin_unlock(ptl);
+
+ if (ret == -ENOENT)
+ return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
+
+ return ret;
+#else /* CONFIG_HUGETLB_PAGE */
+ return -EINVAL;
+#endif
+}
+
static void hmm_pfns_clear(struct hmm_range *range,
uint64_t *pfns,
unsigned long addr,
*pfns = range->values[HMM_PFN_NONE];
}
-static void hmm_pfns_special(struct hmm_range *range)
-{
- unsigned long addr = range->start, i = 0;
-
- for (; addr < range->end; addr += PAGE_SIZE, i++)
- range->pfns[i] = range->values[HMM_PFN_SPECIAL];
-}
-
/*
- * 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
- *
- * 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.
+ * hmm_range_register() - start tracking change to CPU page table over a range
+ * @range: range
+ * @mm: the mm struct for the range of virtual address
+ * @start: start virtual address (inclusive)
+ * @end: end virtual address (exclusive)
+ * @page_shift: expect page shift for the range
+ * Returns 0 on success, -EFAULT if the address space is no longer valid
*
- * NOT CALLING hmm_vma_range_done() IF FUNCTION RETURNS 0 WILL LEAD TO SERIOUS
- * MEMORY CORRUPTION ! YOU HAVE BEEN WARNED !
+ * Track updates to the CPU page table see include/linux/hmm.h
*/
-int hmm_vma_get_pfns(struct hmm_range *range)
+int hmm_range_register(struct hmm_range *range,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long end,
+ unsigned page_shift)
{
- struct vm_area_struct *vma = range->vma;
- struct hmm_vma_walk hmm_vma_walk;
- struct mm_walk mm_walk;
- struct hmm *hmm;
+ unsigned long mask = ((1UL << page_shift) - 1UL);
+
+ range->valid = false;
+ range->hmm = NULL;
- /* Sanity check, this really should not happen ! */
- if (range->start < vma->vm_start || range->start >= vma->vm_end)
+ if ((start & mask) || (end & mask))
return -EINVAL;
- if (range->end < vma->vm_start || range->end > vma->vm_end)
+ if (start >= end)
return -EINVAL;
- hmm = hmm_register(vma->vm_mm);
- if (!hmm)
- return -ENOMEM;
- /* Caller must have registered a mirror, via hmm_mirror_register() ! */
- if (!hmm->mmu_notifier.ops)
- return -EINVAL;
+ range->page_shift = page_shift;
+ range->start = start;
+ range->end = end;
- /* FIXME support hugetlb fs */
- if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL) ||
- vma_is_dax(vma)) {
- hmm_pfns_special(range);
- return -EINVAL;
- }
+ range->hmm = hmm_get_or_create(mm);
+ if (!range->hmm)
+ return -EFAULT;
- if (!(vma->vm_flags & VM_READ)) {
- /*
- * If vma do not allow read access, then assume that it does
- * not allow write access, either. Architecture that allow
- * write without read access are not supported by HMM, because
- * operations such has atomic access would not work.
- */
- hmm_pfns_clear(range, range->pfns, range->start, range->end);
- return -EPERM;
+ /* Check if hmm_mm_destroy() was call. */
+ if (range->hmm->mm == NULL || range->hmm->dead) {
+ hmm_put(range->hmm);
+ return -EFAULT;
}
/* Initialize range to track CPU page table update */
- spin_lock(&hmm->lock);
- range->valid = true;
- list_add_rcu(&range->list, &hmm->ranges);
- spin_unlock(&hmm->lock);
-
- hmm_vma_walk.fault = false;
- hmm_vma_walk.range = range;
- mm_walk.private = &hmm_vma_walk;
-
- mm_walk.vma = vma;
- mm_walk.mm = vma->vm_mm;
- mm_walk.pte_entry = NULL;
- mm_walk.test_walk = NULL;
- mm_walk.hugetlb_entry = NULL;
- mm_walk.pmd_entry = hmm_vma_walk_pmd;
- mm_walk.pte_hole = hmm_vma_walk_hole;
-
- walk_page_range(range->start, range->end, &mm_walk);
+ mutex_lock(&range->hmm->lock);
+
+ list_add_rcu(&range->list, &range->hmm->ranges);
+
+ /*
+ * If there are any concurrent notifiers we have to wait for them for
+ * the range to be valid (see hmm_range_wait_until_valid()).
+ */
+ if (!range->hmm->notifiers)
+ range->valid = true;
+ mutex_unlock(&range->hmm->lock);
+
return 0;
}
-EXPORT_SYMBOL(hmm_vma_get_pfns);
+EXPORT_SYMBOL(hmm_range_register);
/*
- * hmm_vma_range_done() - stop tracking change to CPU page table over a range
- * @range: range being tracked
- * Returns: false if range data has been invalidated, true otherwise
+ * hmm_range_unregister() - stop tracking change to CPU page table over a range
+ * @range: range
*
* Range struct is used to track updates to the CPU page table after a call to
- * either hmm_vma_get_pfns() or hmm_vma_fault(). Once the device driver is done
- * using the data, or wants to lock updates to the data it got from those
- * functions, it must call the hmm_vma_range_done() function, which will then
- * stop tracking CPU page table updates.
- *
- * Note that device driver must still implement general CPU page table update
- * tracking either by using hmm_mirror (see hmm_mirror_register()) or by using
- * the mmu_notifier API directly.
- *
- * CPU page table update tracking done through hmm_range is only temporary and
- * to be used while trying to duplicate CPU page table contents for a range of
- * virtual addresses.
- *
- * There are two ways to use this :
- * again:
- * hmm_vma_get_pfns(range); or hmm_vma_fault(...);
- * trans = device_build_page_table_update_transaction(pfns);
- * device_page_table_lock();
- * if (!hmm_vma_range_done(range)) {
- * device_page_table_unlock();
- * goto again;
- * }
- * device_commit_transaction(trans);
- * device_page_table_unlock();
+ * hmm_range_register(). See include/linux/hmm.h for how to use it.
+ */
+void hmm_range_unregister(struct hmm_range *range)
+{
+ /* Sanity check this really should not happen. */
+ if (range->hmm == NULL || range->end <= range->start)
+ return;
+
+ mutex_lock(&range->hmm->lock);
+ list_del_rcu(&range->list);
+ mutex_unlock(&range->hmm->lock);
+
+ /* Drop reference taken by hmm_range_register() */
+ range->valid = false;
+ hmm_put(range->hmm);
+ range->hmm = NULL;
+}
+EXPORT_SYMBOL(hmm_range_unregister);
+
+/*
+ * hmm_range_snapshot() - snapshot CPU page table for a range
+ * @range: range
+ * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid
+ * permission (for instance asking for write and range is read only),
+ * -EAGAIN if you need to retry, -EFAULT invalid (ie either no valid
+ * vma or it is illegal to access that range), number of valid pages
+ * in range->pfns[] (from range start address).
*
- * Or:
- * hmm_vma_get_pfns(range); or hmm_vma_fault(...);
- * device_page_table_lock();
- * hmm_vma_range_done(range);
- * device_update_page_table(range->pfns);
- * device_page_table_unlock();
+ * This snapshots the CPU page table for a range of virtual addresses. Snapshot
+ * validity is tracked by range struct. See in include/linux/hmm.h for example
+ * on how to use.
*/
-bool hmm_vma_range_done(struct hmm_range *range)
+long hmm_range_snapshot(struct hmm_range *range)
{
- unsigned long npages = (range->end - range->start) >> PAGE_SHIFT;
- struct hmm *hmm;
+ const unsigned long device_vma = VM_IO | VM_PFNMAP | VM_MIXEDMAP;
+ unsigned long start = range->start, end;
+ struct hmm_vma_walk hmm_vma_walk;
+ struct hmm *hmm = range->hmm;
+ struct vm_area_struct *vma;
+ struct mm_walk mm_walk;
- if (range->end <= range->start) {
- BUG();
- return false;
- }
+ /* Check if hmm_mm_destroy() was call. */
+ if (hmm->mm == NULL || hmm->dead)
+ return -EFAULT;
- hmm = hmm_register(range->vma->vm_mm);
- if (!hmm) {
- memset(range->pfns, 0, sizeof(*range->pfns) * npages);
- return false;
- }
+ do {
+ /* If range is no longer valid force retry. */
+ if (!range->valid)
+ return -EAGAIN;
- spin_lock(&hmm->lock);
- list_del_rcu(&range->list);
- spin_unlock(&hmm->lock);
+ vma = find_vma(hmm->mm, start);
+ if (vma == NULL || (vma->vm_flags & device_vma))
+ return -EFAULT;
+
+ if (is_vm_hugetlb_page(vma)) {
+ struct hstate *h = hstate_vma(vma);
- return range->valid;
+ if (huge_page_shift(h) != 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
+ * does not allow write access, either. HMM does not
+ * support architecture that allow write without read.
+ */
+ hmm_pfns_clear(range, range->pfns,
+ range->start, range->end);
+ return -EPERM;
+ }
+
+ range->vma = vma;
+ hmm_vma_walk.pgmap = NULL;
+ hmm_vma_walk.last = start;
+ hmm_vma_walk.fault = false;
+ hmm_vma_walk.range = range;
+ mm_walk.private = &hmm_vma_walk;
+ end = min(range->end, vma->vm_end);
+
+ mm_walk.vma = vma;
+ mm_walk.mm = vma->vm_mm;
+ mm_walk.pte_entry = NULL;
+ mm_walk.test_walk = NULL;
+ mm_walk.hugetlb_entry = NULL;
+ mm_walk.pud_entry = hmm_vma_walk_pud;
+ mm_walk.pmd_entry = hmm_vma_walk_pmd;
+ mm_walk.pte_hole = hmm_vma_walk_hole;
+ mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry;
+
+ walk_page_range(start, end, &mm_walk);
+ start = end;
+ } while (start < range->end);
+
+ return (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
}
-EXPORT_SYMBOL(hmm_vma_range_done);
+EXPORT_SYMBOL(hmm_range_snapshot);
/*
- * hmm_vma_fault() - try to fault some address in a virtual address range
+ * hmm_range_fault() - try to fault some address in a virtual address range
* @range: range being faulted
* @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem)
- * Returns: 0 success, error otherwise (-EAGAIN means mmap_sem have been drop)
+ * 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 (for instance device file vma).
+ * -ENOMEM: Out of memory.
+ * -EPERM: Invalid permission (for instance asking for write and
+ * range is read only).
+ * -EAGAIN: If you need to retry and mmap_sem was drop. This can only
+ * happens if block argument is false.
+ * -EBUSY: If the the range is being invalidated and you should wait
+ * for invalidation to finish.
+ * -EFAULT: Invalid (ie either no valid vma or it is illegal to access
+ * that range), number of valid pages in range->pfns[] (from
+ * range start address).
*
* This is similar to a regular CPU page fault except that it will not trigger
- * any memory migration if the memory being faulted is not accessible by CPUs.
+ * any memory migration if the memory being faulted is not accessible by CPUs
+ * and caller does not ask for migration.
*
* On error, for one virtual address in the range, the function will mark the
* corresponding HMM pfn entry with an error flag.
- *
- * Expected use pattern:
- * retry:
- * down_read(&mm->mmap_sem);
- * // Find vma and address device wants to fault, initialize hmm_pfn_t
- * // array accordingly
- * ret = hmm_vma_fault(range, write, block);
- * switch (ret) {
- * case -EAGAIN:
- * hmm_vma_range_done(range);
- * // You might want to rate limit or yield to play nicely, you may
- * // also commit any valid pfn in the array assuming that you are
- * // getting true from hmm_vma_range_monitor_end()
- * goto retry;
- * case 0:
- * break;
- * case -ENOMEM:
- * case -EINVAL:
- * case -EPERM:
- * default:
- * // Handle error !
- * up_read(&mm->mmap_sem)
- * return;
- * }
- * // Take device driver lock that serialize device page table update
- * driver_lock_device_page_table_update();
- * hmm_vma_range_done(range);
- * // Commit pfns we got from hmm_vma_fault()
- * driver_unlock_device_page_table_update();
- * up_read(&mm->mmap_sem)
- *
- * YOU MUST CALL hmm_vma_range_done() AFTER THIS FUNCTION RETURN SUCCESS (0)
- * BEFORE FREEING THE range struct OR YOU WILL HAVE SERIOUS MEMORY CORRUPTION !
- *
- * YOU HAVE BEEN WARNED !
*/
-int hmm_vma_fault(struct hmm_range *range, bool block)
+long hmm_range_fault(struct hmm_range *range, bool block)
{
- struct vm_area_struct *vma = range->vma;
- unsigned long start = range->start;
+ const unsigned long device_vma = VM_IO | VM_PFNMAP | VM_MIXEDMAP;
+ unsigned long start = range->start, end;
struct hmm_vma_walk hmm_vma_walk;
+ struct hmm *hmm = range->hmm;
+ struct vm_area_struct *vma;
struct mm_walk mm_walk;
- struct hmm *hmm;
int ret;
- /* Sanity check, this really should not happen ! */
- if (range->start < vma->vm_start || range->start >= vma->vm_end)
- return -EINVAL;
- if (range->end < vma->vm_start || range->end > vma->vm_end)
- return -EINVAL;
+ /* Check if hmm_mm_destroy() was call. */
+ if (hmm->mm == NULL || hmm->dead)
+ return -EFAULT;
- hmm = hmm_register(vma->vm_mm);
- if (!hmm) {
- hmm_pfns_clear(range, range->pfns, range->start, range->end);
- return -ENOMEM;
- }
- /* Caller must have registered a mirror using hmm_mirror_register() */
- if (!hmm->mmu_notifier.ops)
- return -EINVAL;
+ do {
+ /* If range is no longer valid force retry. */
+ if (!range->valid) {
+ up_read(&hmm->mm->mmap_sem);
+ return -EAGAIN;
+ }
- /* FIXME support hugetlb fs */
- if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL) ||
- vma_is_dax(vma)) {
- hmm_pfns_special(range);
- return -EINVAL;
- }
+ vma = find_vma(hmm->mm, start);
+ 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
+ * does not allow write access, either. HMM does not
+ * support architecture that allow write without read.
+ */
+ hmm_pfns_clear(range, range->pfns,
+ range->start, range->end);
+ return -EPERM;
+ }
+
+ range->vma = vma;
+ hmm_vma_walk.pgmap = NULL;
+ hmm_vma_walk.last = start;
+ hmm_vma_walk.fault = true;
+ hmm_vma_walk.block = block;
+ hmm_vma_walk.range = range;
+ mm_walk.private = &hmm_vma_walk;
+ end = min(range->end, vma->vm_end);
+
+ mm_walk.vma = vma;
+ mm_walk.mm = vma->vm_mm;
+ mm_walk.pte_entry = NULL;
+ mm_walk.test_walk = NULL;
+ mm_walk.hugetlb_entry = NULL;
+ mm_walk.pud_entry = hmm_vma_walk_pud;
+ mm_walk.pmd_entry = hmm_vma_walk_pmd;
+ mm_walk.pte_hole = hmm_vma_walk_hole;
+ mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry;
+
+ do {
+ ret = walk_page_range(start, end, &mm_walk);
+ start = hmm_vma_walk.last;
+
+ /* Keep trying while the range is valid. */
+ } while (ret == -EBUSY && range->valid);
+
+ if (ret) {
+ unsigned long i;
+
+ i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
+ hmm_pfns_clear(range, &range->pfns[i],
+ hmm_vma_walk.last, range->end);
+ return ret;
+ }
+ start = end;
+
+ } while (start < range->end);
+
+ return (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
+}
+EXPORT_SYMBOL(hmm_range_fault);
+
+/**
+ * hmm_range_dma_map() - hmm_range_fault() and dma map page all in one.
+ * @range: range being faulted
+ * @device: device against to dma map page to
+ * @daddrs: dma address of mapped pages
+ * @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem)
+ * Returns: number of pages mapped on success, -EAGAIN if mmap_sem have been
+ * drop and you need to try again, some other error value otherwise
+ *
+ * Note same usage pattern as hmm_range_fault().
+ */
+long hmm_range_dma_map(struct hmm_range *range,
+ struct device *device,
+ dma_addr_t *daddrs,
+ bool block)
+{
+ unsigned long i, npages, mapped;
+ long ret;
+
+ ret = hmm_range_fault(range, block);
+ if (ret <= 0)
+ return ret ? ret : -EBUSY;
+
+ npages = (range->end - range->start) >> PAGE_SHIFT;
+ for (i = 0, mapped = 0; i < npages; ++i) {
+ enum dma_data_direction dir = DMA_TO_DEVICE;
+ struct page *page;
- if (!(vma->vm_flags & VM_READ)) {
/*
- * If vma do not allow read access, then assume that it does
- * not allow write access, either. Architecture that allow
- * write without read access are not supported by HMM, because
- * operations such has atomic access would not work.
+ * FIXME need to update DMA API to provide invalid DMA address
+ * value instead of a function to test dma address value. This
+ * would remove lot of dumb code duplicated accross many arch.
+ *
+ * For now setting it to 0 here is good enough as the pfns[]
+ * value is what is use to check what is valid and what isn't.
*/
- hmm_pfns_clear(range, range->pfns, range->start, range->end);
- return -EPERM;
+ daddrs[i] = 0;
+
+ page = hmm_device_entry_to_page(range, range->pfns[i]);
+ if (page == NULL)
+ continue;
+
+ /* Check if range is being invalidated */
+ if (!range->valid) {
+ ret = -EBUSY;
+ goto unmap;
+ }
+
+ /* If it is read and write than map bi-directional. */
+ if (range->pfns[i] & range->flags[HMM_PFN_WRITE])
+ dir = DMA_BIDIRECTIONAL;
+
+ daddrs[i] = dma_map_page(device, page, 0, PAGE_SIZE, dir);
+ if (dma_mapping_error(device, daddrs[i])) {
+ ret = -EFAULT;
+ goto unmap;
+ }
+
+ mapped++;
}
- /* Initialize range to track CPU page table update */
- spin_lock(&hmm->lock);
- range->valid = true;
- list_add_rcu(&range->list, &hmm->ranges);
- spin_unlock(&hmm->lock);
-
- hmm_vma_walk.fault = true;
- hmm_vma_walk.block = block;
- 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;
- mm_walk.pte_entry = NULL;
- mm_walk.test_walk = NULL;
- mm_walk.hugetlb_entry = NULL;
- mm_walk.pmd_entry = hmm_vma_walk_pmd;
- mm_walk.pte_hole = hmm_vma_walk_hole;
+ return mapped;
- do {
- ret = walk_page_range(start, range->end, &mm_walk);
- start = hmm_vma_walk.last;
- } while (ret == -EAGAIN);
+unmap:
+ for (npages = i, i = 0; (i < npages) && mapped; ++i) {
+ enum dma_data_direction dir = DMA_TO_DEVICE;
+ struct page *page;
- if (ret) {
- unsigned long i;
+ page = hmm_device_entry_to_page(range, range->pfns[i]);
+ if (page == NULL)
+ continue;
+
+ if (dma_mapping_error(device, daddrs[i]))
+ continue;
- i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
- hmm_pfns_clear(range, &range->pfns[i], hmm_vma_walk.last,
- range->end);
- hmm_vma_range_done(range);
+ /* If it is read and write than map bi-directional. */
+ if (range->pfns[i] & range->flags[HMM_PFN_WRITE])
+ dir = DMA_BIDIRECTIONAL;
+
+ dma_unmap_page(device, daddrs[i], PAGE_SIZE, dir);
+ mapped--;
}
+
return ret;
}
-EXPORT_SYMBOL(hmm_vma_fault);
+EXPORT_SYMBOL(hmm_range_dma_map);
+
+/**
+ * hmm_range_dma_unmap() - unmap range of that was map with hmm_range_dma_map()
+ * @range: range being unmapped
+ * @vma: the vma against which the range (optional)
+ * @device: device against which dma map was done
+ * @daddrs: dma address of mapped pages
+ * @dirty: dirty page if it had the write flag set
+ * Returns: number of page unmapped on success, -EINVAL otherwise
+ *
+ * Note that caller MUST abide by mmu notifier or use HMM mirror and abide
+ * to the sync_cpu_device_pagetables() callback so that it is safe here to
+ * call set_page_dirty(). Caller must also take appropriate locks to avoid
+ * concurrent mmu notifier or sync_cpu_device_pagetables() to make progress.
+ */
+long hmm_range_dma_unmap(struct hmm_range *range,
+ struct vm_area_struct *vma,
+ struct device *device,
+ dma_addr_t *daddrs,
+ bool dirty)
+{
+ unsigned long i, npages;
+ long cpages = 0;
+
+ /* Sanity check. */
+ if (range->end <= range->start)
+ return -EINVAL;
+ if (!daddrs)
+ return -EINVAL;
+ if (!range->pfns)
+ return -EINVAL;
+
+ npages = (range->end - range->start) >> PAGE_SHIFT;
+ for (i = 0; i < npages; ++i) {
+ enum dma_data_direction dir = DMA_TO_DEVICE;
+ struct page *page;
+
+ page = hmm_device_entry_to_page(range, range->pfns[i]);
+ if (page == NULL)
+ continue;
+
+ /* If it is read and write than map bi-directional. */
+ if (range->pfns[i] & range->flags[HMM_PFN_WRITE]) {
+ dir = DMA_BIDIRECTIONAL;
+
+ /*
+ * See comments in function description on why it is
+ * safe here to call set_page_dirty()
+ */
+ if (dirty)
+ set_page_dirty(page);
+ }
+
+ /* Unmap and clear pfns/dma address */
+ dma_unmap_page(device, daddrs[i], PAGE_SIZE, dir);
+ range->pfns[i] = range->values[HMM_PFN_NONE];
+ /* FIXME see comments in hmm_vma_dma_map() */
+ daddrs[i] = 0;
+ cpages++;
+ }
+
+ return cpages;
+}
+EXPORT_SYMBOL(hmm_range_dma_unmap);
#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
projects / linux.git / blobdiff