Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 614 insertions, 0 deletions

diff --git a/mm/hmm.c b/mm/hmm.c
new file mode 100644
index 0000000000..277ddcab49
--- /dev/null
+++ b/mm/hmm.c
@@ -0,0 +1,614 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2013 Red Hat Inc.
+ *
+ * Authors: Jérôme Glisse <jglisse@redhat.com>
+ */
+/*
+ * Refer to include/linux/hmm.h for information about heterogeneous memory
+ * management or HMM for short.
+ */
+#include <linux/pagewalk.h>
+#include <linux/hmm.h>
+#include <linux/init.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/mmzone.h>
+#include <linux/pagemap.h>
+#include <linux/swapops.h>
+#include <linux/hugetlb.h>
+#include <linux/memremap.h>
+#include <linux/sched/mm.h>
+#include <linux/jump_label.h>
+#include <linux/dma-mapping.h>
+#include <linux/mmu_notifier.h>
+#include <linux/memory_hotplug.h>
+
+#include "internal.h"
+
+struct hmm_vma_walk {
+	struct hmm_range	*range;
+	unsigned long		last;
+};
+
+enum {
+	HMM_NEED_FAULT = 1 << 0,
+	HMM_NEED_WRITE_FAULT = 1 << 1,
+	HMM_NEED_ALL_BITS = HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT,
+};
+
+static int hmm_pfns_fill(unsigned long addr, unsigned long end,
+			 struct hmm_range *range, unsigned long cpu_flags)
+{
+	unsigned long i = (addr - range->start) >> PAGE_SHIFT;
+
+	for (; addr < end; addr += PAGE_SIZE, i++)
+		range->hmm_pfns[i] = cpu_flags;
+	return 0;
+}
+
+/*
+ * hmm_vma_fault() - fault in a range lacking valid pmd or pte(s)
+ * @addr: range virtual start address (inclusive)
+ * @end: range virtual end address (exclusive)
+ * @required_fault: HMM_NEED_* flags
+ * @walk: mm_walk structure
+ * Return: -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.
+ */
+static int hmm_vma_fault(unsigned long addr, unsigned long end,
+			 unsigned int required_fault, struct mm_walk *walk)
+{
+	struct hmm_vma_walk *hmm_vma_walk = walk->private;
+	struct vm_area_struct *vma = walk->vma;
+	unsigned int fault_flags = FAULT_FLAG_REMOTE;
+
+	WARN_ON_ONCE(!required_fault);
+	hmm_vma_walk->last = addr;
+
+	if (required_fault & HMM_NEED_WRITE_FAULT) {
+		if (!(vma->vm_flags & VM_WRITE))
+			return -EPERM;
+		fault_flags |= FAULT_FLAG_WRITE;
+	}
+
+	for (; addr < end; addr += PAGE_SIZE)
+		if (handle_mm_fault(vma, addr, fault_flags, NULL) &
+		    VM_FAULT_ERROR)
+			return -EFAULT;
+	return -EBUSY;
+}
+
+static unsigned int hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
+				       unsigned long pfn_req_flags,
+				       unsigned long cpu_flags)
+{
+	struct hmm_range *range = hmm_vma_walk->range;
+
+	/*
+	 * So we not only consider the individual per page request we also
+	 * consider the default flags requested for the range. The API can
+	 * be used 2 ways. The first one where the HMM user coalesces
+	 * multiple page faults into one request and sets flags per pfn for
+	 * those faults. The second one where the HMM user wants 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.
+	 */
+	pfn_req_flags &= range->pfn_flags_mask;
+	pfn_req_flags |= range->default_flags;
+
+	/* We aren't ask to do anything ... */
+	if (!(pfn_req_flags & HMM_PFN_REQ_FAULT))
+		return 0;
+
+	/* Need to write fault ? */
+	if ((pfn_req_flags & HMM_PFN_REQ_WRITE) &&
+	    !(cpu_flags & HMM_PFN_WRITE))
+		return HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT;
+
+	/* If CPU page table is not valid then we need to fault */
+	if (!(cpu_flags & HMM_PFN_VALID))
+		return HMM_NEED_FAULT;
+	return 0;
+}
+
+static unsigned int
+hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
+		     const unsigned long hmm_pfns[], unsigned long npages,
+		     unsigned long cpu_flags)
+{
+	struct hmm_range *range = hmm_vma_walk->range;
+	unsigned int required_fault = 0;
+	unsigned long i;
+
+	/*
+	 * If the default flags do not request to fault pages, and the mask does
+	 * not allow for individual pages to be faulted, then
+	 * hmm_pte_need_fault() will always return 0.
+	 */
+	if (!((range->default_flags | range->pfn_flags_mask) &
+	      HMM_PFN_REQ_FAULT))
+		return 0;
+
+	for (i = 0; i < npages; ++i) {
+		required_fault |= hmm_pte_need_fault(hmm_vma_walk, hmm_pfns[i],
+						     cpu_flags);
+		if (required_fault == HMM_NEED_ALL_BITS)
+			return required_fault;
+	}
+	return required_fault;
+}
+
+static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
+			     __always_unused int depth, struct mm_walk *walk)
+{
+	struct hmm_vma_walk *hmm_vma_walk = walk->private;
+	struct hmm_range *range = hmm_vma_walk->range;
+	unsigned int required_fault;
+	unsigned long i, npages;
+	unsigned long *hmm_pfns;
+
+	i = (addr - range->start) >> PAGE_SHIFT;
+	npages = (end - addr) >> PAGE_SHIFT;
+	hmm_pfns = &range->hmm_pfns[i];
+	required_fault =
+		hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0);
+	if (!walk->vma) {
+		if (required_fault)
+			return -EFAULT;
+		return hmm_pfns_fill(addr, end, range, HMM_PFN_ERROR);
+	}
+	if (required_fault)
+		return hmm_vma_fault(addr, end, required_fault, walk);
+	return hmm_pfns_fill(addr, end, range, 0);
+}
+
+static inline unsigned long hmm_pfn_flags_order(unsigned long order)
+{
+	return order << HMM_PFN_ORDER_SHIFT;
+}
+
+static inline unsigned long pmd_to_hmm_pfn_flags(struct hmm_range *range,
+						 pmd_t pmd)
+{
+	if (pmd_protnone(pmd))
+		return 0;
+	return (pmd_write(pmd) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
+				 HMM_PFN_VALID) |
+	       hmm_pfn_flags_order(PMD_SHIFT - PAGE_SHIFT);
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
+			      unsigned long end, unsigned long hmm_pfns[],
+			      pmd_t pmd)
+{
+	struct hmm_vma_walk *hmm_vma_walk = walk->private;
+	struct hmm_range *range = hmm_vma_walk->range;
+	unsigned long pfn, npages, i;
+	unsigned int required_fault;
+	unsigned long cpu_flags;
+
+	npages = (end - addr) >> PAGE_SHIFT;
+	cpu_flags = pmd_to_hmm_pfn_flags(range, pmd);
+	required_fault =
+		hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, cpu_flags);
+	if (required_fault)
+		return hmm_vma_fault(addr, end, required_fault, walk);
+
+	pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
+		hmm_pfns[i] = pfn | cpu_flags;
+	return 0;
+}
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+/* stub to allow the code below to compile */
+int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
+		unsigned long end, unsigned long hmm_pfns[], pmd_t pmd);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+static inline unsigned long pte_to_hmm_pfn_flags(struct hmm_range *range,
+						 pte_t pte)
+{
+	if (pte_none(pte) || !pte_present(pte) || pte_protnone(pte))
+		return 0;
+	return pte_write(pte) ? (HMM_PFN_VALID | HMM_PFN_WRITE) : HMM_PFN_VALID;
+}
+
+static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
+			      unsigned long end, pmd_t *pmdp, pte_t *ptep,
+			      unsigned long *hmm_pfn)
+{
+	struct hmm_vma_walk *hmm_vma_walk = walk->private;
+	struct hmm_range *range = hmm_vma_walk->range;
+	unsigned int required_fault;
+	unsigned long cpu_flags;
+	pte_t pte = ptep_get(ptep);
+	uint64_t pfn_req_flags = *hmm_pfn;
+
+	if (pte_none_mostly(pte)) {
+		required_fault =
+			hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
+		if (required_fault)
+			goto fault;
+		*hmm_pfn = 0;
+		return 0;
+	}
+
+	if (!pte_present(pte)) {
+		swp_entry_t entry = pte_to_swp_entry(pte);
+
+		/*
+		 * Don't fault in device private pages owned by the caller,
+		 * just report the PFN.
+		 */
+		if (is_device_private_entry(entry) &&
+		    pfn_swap_entry_to_page(entry)->pgmap->owner ==
+		    range->dev_private_owner) {
+			cpu_flags = HMM_PFN_VALID;
+			if (is_writable_device_private_entry(entry))
+				cpu_flags |= HMM_PFN_WRITE;
+			*hmm_pfn = swp_offset_pfn(entry) | cpu_flags;
+			return 0;
+		}
+
+		required_fault =
+			hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
+		if (!required_fault) {
+			*hmm_pfn = 0;
+			return 0;
+		}
+
+		if (!non_swap_entry(entry))
+			goto fault;
+
+		if (is_device_private_entry(entry))
+			goto fault;
+
+		if (is_device_exclusive_entry(entry))
+			goto fault;
+
+		if (is_migration_entry(entry)) {
+			pte_unmap(ptep);
+			hmm_vma_walk->last = addr;
+			migration_entry_wait(walk->mm, pmdp, addr);
+			return -EBUSY;
+		}
+
+		/* Report error for everything else */
+		pte_unmap(ptep);
+		return -EFAULT;
+	}
+
+	cpu_flags = pte_to_hmm_pfn_flags(range, pte);
+	required_fault =
+		hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, cpu_flags);
+	if (required_fault)
+		goto fault;
+
+	/*
+	 * Bypass devmap pte such as DAX page when all pfn requested
+	 * flags(pfn_req_flags) are fulfilled.
+	 * Since each architecture defines a struct page for the zero page, just
+	 * fall through and treat it like a normal page.
+	 */
+	if (!vm_normal_page(walk->vma, addr, pte) &&
+	    !pte_devmap(pte) &&
+	    !is_zero_pfn(pte_pfn(pte))) {
+		if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) {
+			pte_unmap(ptep);
+			return -EFAULT;
+		}
+		*hmm_pfn = HMM_PFN_ERROR;
+		return 0;
+	}
+
+	*hmm_pfn = pte_pfn(pte) | cpu_flags;
+	return 0;
+
+fault:
+	pte_unmap(ptep);
+	/* Fault any virtual address we were asked to fault */
+	return hmm_vma_fault(addr, end, required_fault, walk);
+}
+
+static int hmm_vma_walk_pmd(pmd_t *pmdp,
+			    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 *hmm_pfns =
+		&range->hmm_pfns[(start - range->start) >> PAGE_SHIFT];
+	unsigned long npages = (end - start) >> PAGE_SHIFT;
+	unsigned long addr = start;
+	pte_t *ptep;
+	pmd_t pmd;
+
+again:
+	pmd = pmdp_get_lockless(pmdp);
+	if (pmd_none(pmd))
+		return hmm_vma_walk_hole(start, end, -1, walk);
+
+	if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
+		if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0)) {
+			hmm_vma_walk->last = addr;
+			pmd_migration_entry_wait(walk->mm, pmdp);
+			return -EBUSY;
+		}
+		return hmm_pfns_fill(start, end, range, 0);
+	}
+
+	if (!pmd_present(pmd)) {
+		if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0))
+			return -EFAULT;
+		return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
+	}
+
+	if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) {
+		/*
+		 * No need to take pmd_lock here, even if some other thread
+		 * is splitting the huge pmd we will get that event through
+		 * mmu_notifier callback.
+		 *
+		 * So just read pmd value and check again it's a transparent
+		 * huge or device mapping one and compute corresponding pfn
+		 * values.
+		 */
+		pmd = pmdp_get_lockless(pmdp);
+		if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
+			goto again;
+
+		return hmm_vma_handle_pmd(walk, addr, end, hmm_pfns, pmd);
+	}
+
+	/*
+	 * We have handled all the valid cases above ie either none, migration,
+	 * huge or transparent huge. At this point either it is a valid pmd
+	 * entry pointing to pte directory or it is a bad pmd that will not
+	 * recover.
+	 */
+	if (pmd_bad(pmd)) {
+		if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0))
+			return -EFAULT;
+		return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
+	}
+
+	ptep = pte_offset_map(pmdp, addr);
+	if (!ptep)
+		goto again;
+	for (; addr < end; addr += PAGE_SIZE, ptep++, hmm_pfns++) {
+		int r;
+
+		r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, hmm_pfns);
+		if (r) {
+			/* hmm_vma_handle_pte() did pte_unmap() */
+			return r;
+		}
+	}
+	pte_unmap(ptep - 1);
+	return 0;
+}
+
+#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && \
+    defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
+static inline unsigned long pud_to_hmm_pfn_flags(struct hmm_range *range,
+						 pud_t pud)
+{
+	if (!pud_present(pud))
+		return 0;
+	return (pud_write(pud) ? (HMM_PFN_VALID | HMM_PFN_WRITE) :
+				 HMM_PFN_VALID) |
+	       hmm_pfn_flags_order(PUD_SHIFT - PAGE_SHIFT);
+}
+
+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;
+	pud_t pud;
+	spinlock_t *ptl = pud_trans_huge_lock(pudp, walk->vma);
+
+	if (!ptl)
+		return 0;
+
+	/* Normally we don't want to split the huge page */
+	walk->action = ACTION_CONTINUE;
+
+	pud = READ_ONCE(*pudp);
+	if (pud_none(pud)) {
+		spin_unlock(ptl);
+		return hmm_vma_walk_hole(start, end, -1, walk);
+	}
+
+	if (pud_huge(pud) && pud_devmap(pud)) {
+		unsigned long i, npages, pfn;
+		unsigned int required_fault;
+		unsigned long *hmm_pfns;
+		unsigned long cpu_flags;
+
+		if (!pud_present(pud)) {
+			spin_unlock(ptl);
+			return hmm_vma_walk_hole(start, end, -1, walk);
+		}
+
+		i = (addr - range->start) >> PAGE_SHIFT;
+		npages = (end - addr) >> PAGE_SHIFT;
+		hmm_pfns = &range->hmm_pfns[i];
+
+		cpu_flags = pud_to_hmm_pfn_flags(range, pud);
+		required_fault = hmm_range_need_fault(hmm_vma_walk, hmm_pfns,
+						      npages, cpu_flags);
+		if (required_fault) {
+			spin_unlock(ptl);
+			return hmm_vma_fault(addr, end, required_fault, walk);
+		}
+
+		pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+		for (i = 0; i < npages; ++i, ++pfn)
+			hmm_pfns[i] = pfn | cpu_flags;
+		goto out_unlock;
+	}
+
+	/* Ask for the PUD to be split */
+	walk->action = ACTION_SUBTREE;
+
+out_unlock:
+	spin_unlock(ptl);
+	return 0;
+}
+#else
+#define hmm_vma_walk_pud	NULL
+#endif
+
+#ifdef CONFIG_HUGETLB_PAGE
+static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
+				      unsigned long start, unsigned long end,
+				      struct mm_walk *walk)
+{
+	unsigned long addr = start, i, pfn;
+	struct hmm_vma_walk *hmm_vma_walk = walk->private;
+	struct hmm_range *range = hmm_vma_walk->range;
+	struct vm_area_struct *vma = walk->vma;
+	unsigned int required_fault;
+	unsigned long pfn_req_flags;
+	unsigned long cpu_flags;
+	spinlock_t *ptl;
+	pte_t entry;
+
+	ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte);
+	entry = huge_ptep_get(pte);
+
+	i = (start - range->start) >> PAGE_SHIFT;
+	pfn_req_flags = range->hmm_pfns[i];
+	cpu_flags = pte_to_hmm_pfn_flags(range, entry) |
+		    hmm_pfn_flags_order(huge_page_order(hstate_vma(vma)));
+	required_fault =
+		hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, cpu_flags);
+	if (required_fault) {
+		int ret;
+
+		spin_unlock(ptl);
+		hugetlb_vma_unlock_read(vma);
+		/*
+		 * Avoid deadlock: drop the vma lock before calling
+		 * hmm_vma_fault(), which will itself potentially take and
+		 * drop the vma lock. This is also correct from a
+		 * protection point of view, because there is no further
+		 * use here of either pte or ptl after dropping the vma
+		 * lock.
+		 */
+		ret = hmm_vma_fault(addr, end, required_fault, walk);
+		hugetlb_vma_lock_read(vma);
+		return ret;
+	}
+
+	pfn = pte_pfn(entry) + ((start & ~hmask) >> PAGE_SHIFT);
+	for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
+		range->hmm_pfns[i] = pfn | cpu_flags;
+
+	spin_unlock(ptl);
+	return 0;
+}
+#else
+#define hmm_vma_walk_hugetlb_entry NULL
+#endif /* CONFIG_HUGETLB_PAGE */
+
+static int hmm_vma_walk_test(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;
+	struct vm_area_struct *vma = walk->vma;
+
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)) &&
+	    vma->vm_flags & VM_READ)
+		return 0;
+
+	/*
+	 * vma ranges that don't have struct page backing them or map I/O
+	 * devices directly cannot be handled by hmm_range_fault().
+	 *
+	 * If the vma does not allow read access, then assume that it does not
+	 * allow write access either. HMM does not support architectures that
+	 * allow write without read.
+	 *
+	 * If a fault is requested for an unsupported range then it is a hard
+	 * failure.
+	 */
+	if (hmm_range_need_fault(hmm_vma_walk,
+				 range->hmm_pfns +
+					 ((start - range->start) >> PAGE_SHIFT),
+				 (end - start) >> PAGE_SHIFT, 0))
+		return -EFAULT;
+
+	hmm_pfns_fill(start, end, range, HMM_PFN_ERROR);
+
+	/* Skip this vma and continue processing the next vma. */
+	return 1;
+}
+
+static const struct mm_walk_ops hmm_walk_ops = {
+	.pud_entry	= hmm_vma_walk_pud,
+	.pmd_entry	= hmm_vma_walk_pmd,
+	.pte_hole	= hmm_vma_walk_hole,
+	.hugetlb_entry	= hmm_vma_walk_hugetlb_entry,
+	.test_walk	= hmm_vma_walk_test,
+	.walk_lock	= PGWALK_RDLOCK,
+};
+
+/**
+ * hmm_range_fault - try to fault some address in a virtual address range
+ * @range:	argument structure
+ *
+ * Returns 0 on success or one of the following error codes:
+ *
+ * -EINVAL:	Invalid arguments or mm or virtual address is in an invalid vma
+ *		(e.g., device file vma).
+ * -ENOMEM:	Out of memory.
+ * -EPERM:	Invalid permission (e.g., asking for write and range is read
+ *		only).
+ * -EBUSY:	The range has been invalidated and the caller needs to wait for
+ *		the invalidation to finish.
+ * -EFAULT:     A page was requested to be valid and could not be made valid
+ *              ie it has no backing VMA or it is illegal to access
+ *
+ * This is similar to get_user_pages(), except that it can read the page tables
+ * without mutating them (ie causing faults).
+ */
+int hmm_range_fault(struct hmm_range *range)
+{
+	struct hmm_vma_walk hmm_vma_walk = {
+		.range = range,
+		.last = range->start,
+	};
+	struct mm_struct *mm = range->notifier->mm;
+	int ret;
+
+	mmap_assert_locked(mm);
+
+	do {
+		/* If range is no longer valid force retry. */
+		if (mmu_interval_check_retry(range->notifier,
+					     range->notifier_seq))
+			return -EBUSY;
+		ret = walk_page_range(mm, hmm_vma_walk.last, range->end,
+				      &hmm_walk_ops, &hmm_vma_walk);
+		/*
+		 * When -EBUSY is returned the loop restarts with
+		 * hmm_vma_walk.last set to an address that has not been stored
+		 * in pfns. All entries < last in the pfn array are set to their
+		 * output, and all >= are still at their input values.
+		 */
+	} while (ret == -EBUSY);
+	return ret;
+}
+EXPORT_SYMBOL(hmm_range_fault);