// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright 2013 Red Hat Inc. * * Authors: Jérôme Glisse */ /* * Refer to include/linux/hmm.h for information about heterogeneous memory * management or HMM for short. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" struct hmm_vma_walk { struct hmm_range *range; bool *locked; unsigned long last; unsigned long end; unsigned int required_fault; }; /* * Internal sentinel returned by walk callbacks when they need a page fault. * The callback stores end/required_fault in hmm_vma_walk; the outer loop * consumes the sentinel and never propagates it to the caller. */ #define HMM_FAULT_PENDING -EAGAIN /* * Internal sentinel returned by hmm_do_fault() when handle_mm_fault() * completes a page fault with the mmap lock dropped. hmm_do_fault() sets * *locked = false; the outer loop consumes the sentinel and never propagates * it to the caller. */ #define HMM_FAULT_UNLOCKED -ENOLCK enum { HMM_NEED_FAULT = 1 << 0, HMM_NEED_WRITE_FAULT = 1 << 1, HMM_NEED_ALL_BITS = HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT, }; enum { /* These flags are carried from input-to-output */ HMM_PFN_INOUT_FLAGS = HMM_PFN_DMA_MAPPED | HMM_PFN_P2PDMA | HMM_PFN_P2PDMA_BUS, }; 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] &= HMM_PFN_INOUT_FLAGS; range->hmm_pfns[i] |= cpu_flags; } return 0; } /* * hmm_record_fault() - record a range that needs to be faulted in * * Called by the walk callbacks when they discover that part of the range * needs a page fault. The callback records what to fault and returns * HMM_FAULT_PENDING; the outer loop in hmm_range_fault_locked() drops * back out of walk_page_range() and invokes handle_mm_fault() from a context * where no page-table or hugetlb_vma_lock is held. */ static int hmm_record_fault(unsigned long addr, unsigned long end, unsigned int required_fault, struct mm_walk *walk) { struct hmm_vma_walk *hmm_vma_walk = walk->private; WARN_ON_ONCE(!required_fault); hmm_vma_walk->last = addr; hmm_vma_walk->end = end; hmm_vma_walk->required_fault = required_fault; return HMM_FAULT_PENDING; } 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_record_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; } #ifdef CONFIG_TRANSPARENT_HUGEPAGE 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); } 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_record_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] &= HMM_PFN_INOUT_FLAGS; 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; uint64_t new_pfn_flags = 0; /* * Any other marker than a UFFD WP marker will result in a fault error * that will be correctly handled, so we need only check for UFFD WP * here. */ if (pte_none(pte) || pte_is_uffd_wp_marker(pte)) { required_fault = hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0); if (required_fault) goto fault; goto out; } if (!pte_present(pte)) { const softleaf_t entry = softleaf_from_pte(pte); /* * Don't fault in device private pages owned by the caller, * just report the PFN. */ if (softleaf_is_device_private(entry) && page_pgmap(softleaf_to_page(entry))->owner == range->dev_private_owner) { cpu_flags = HMM_PFN_VALID; if (softleaf_is_device_private_write(entry)) cpu_flags |= HMM_PFN_WRITE; new_pfn_flags = softleaf_to_pfn(entry) | cpu_flags; goto out; } required_fault = hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0); if (!required_fault) goto out; if (softleaf_is_swap(entry)) goto fault; if (softleaf_is_device_private(entry)) goto fault; if (softleaf_is_device_exclusive(entry)) goto fault; if (softleaf_is_migration(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; /* * 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) && !is_zero_pfn(pte_pfn(pte))) { if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) { pte_unmap(ptep); return -EFAULT; } new_pfn_flags = HMM_PFN_ERROR; goto out; } new_pfn_flags = pte_pfn(pte) | cpu_flags; out: *hmm_pfn = (*hmm_pfn & HMM_PFN_INOUT_FLAGS) | new_pfn_flags; return 0; fault: pte_unmap(ptep); /* Fault any virtual address we were asked to fault */ return hmm_record_fault(addr, end, required_fault, walk); } #ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES static int hmm_vma_handle_absent_pmd(struct mm_walk *walk, unsigned long start, 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 npages = (end - start) >> PAGE_SHIFT; const softleaf_t entry = softleaf_from_pmd(pmd); unsigned long addr = start; unsigned int required_fault; if (softleaf_is_device_private(entry) && softleaf_to_folio(entry)->pgmap->owner == range->dev_private_owner) { unsigned long cpu_flags = HMM_PFN_VALID | hmm_pfn_flags_order(PMD_SHIFT - PAGE_SHIFT); unsigned long pfn = softleaf_to_pfn(entry); unsigned long i; if (softleaf_is_device_private_write(entry)) cpu_flags |= HMM_PFN_WRITE; /* * Fully populate the PFN list though subsequent PFNs could be * inferred, because drivers which are not yet aware of large * folios probably do not support sparsely populated PFN lists. */ for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) { hmm_pfns[i] &= HMM_PFN_INOUT_FLAGS; hmm_pfns[i] |= pfn | cpu_flags; } return 0; } required_fault = hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0); if (required_fault) { if (softleaf_is_device_private(entry)) return hmm_record_fault(addr, end, required_fault, walk); else return -EFAULT; } return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR); } #else static int hmm_vma_handle_absent_pmd(struct mm_walk *walk, unsigned long start, 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 npages = (end - start) >> PAGE_SHIFT; if (hmm_range_need_fault(hmm_vma_walk, hmm_pfns, npages, 0)) return -EFAULT; return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR); } #endif /* CONFIG_ARCH_HAS_PMD_SOFTLEAVES */ 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() && pmd_is_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)) return hmm_vma_handle_absent_pmd(walk, start, end, hmm_pfns, pmd); if (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_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_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 = pudp_get(pudp); if (!pud_present(pud)) { spin_unlock(ptl); return hmm_vma_walk_hole(start, end, -1, walk); } if (pud_leaf(pud)) { unsigned long i, npages, pfn; unsigned int required_fault; unsigned long *hmm_pfns; unsigned long cpu_flags; 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_record_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] &= HMM_PFN_INOUT_FLAGS; 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(walk->mm, addr, 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) { spin_unlock(ptl); return hmm_record_fault(addr, end, required_fault, walk); } pfn = pte_pfn(entry) + ((start & ~hmask) >> PAGE_SHIFT); for (; addr < end; addr += PAGE_SIZE, i++, pfn++) { range->hmm_pfns[i] &= HMM_PFN_INOUT_FLAGS; 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_do_fault - fault in a range recorded by a walk callback * * Called from the outer loop in hmm_range_fault_locked() after a callback * returned HMM_FAULT_PENDING. At this point we hold only mmap_lock; * the page-table spinlock and any hugetlb_vma_lock acquired by the walk * framework have already been released by the unwind. * * Returns -EBUSY on success (all pages faulted, caller should re-walk). * Returns a negative errno on failure. */ static int hmm_do_fault(struct mm_struct *mm, struct hmm_vma_walk *hmm_vma_walk) { unsigned long addr = hmm_vma_walk->last; unsigned long end = hmm_vma_walk->end; unsigned int required_fault = hmm_vma_walk->required_fault; unsigned int fault_flags = FAULT_FLAG_REMOTE; struct vm_area_struct *vma; if (hmm_vma_walk->locked) fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; vma = vma_lookup(mm, addr); if (!vma) return -EFAULT; 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) { vm_fault_t ret; ret = handle_mm_fault(vma, addr, fault_flags, NULL); if (ret & (VM_FAULT_COMPLETED | VM_FAULT_RETRY)) { if (hmm_vma_walk->locked) /* needed by sparse */ *hmm_vma_walk->locked = false; else WARN_ON_ONCE(1); /* broken fault handler */ return HMM_FAULT_UNLOCKED; } if (ret & VM_FAULT_ERROR) { int err = vm_fault_to_errno(ret, 0); if (WARN_ON(!err)) err = -EINVAL; return err; } } return -EBUSY; } static int hmm_range_fault_locked(struct hmm_range *range, bool *locked) { struct hmm_vma_walk hmm_vma_walk = { .range = range, .locked = locked, .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 HMM_FAULT_PENDING is returned a walk callback * recorded a range that needs handle_mm_fault(); * hmm_do_fault() runs the fault outside walk_page_range() * (so no page-table or hugetlb_vma_lock is held) and * returns -EBUSY so the loop re-walks and picks up the * now-present entries. */ if (ret == HMM_FAULT_PENDING) { ret = hmm_do_fault(mm, &hmm_vma_walk); if (ret == HMM_FAULT_UNLOCKED) { if (fatal_signal_pending(current)) return -EINTR; return -EBUSY; } } /* * 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; } /** * 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). * * The mmap lock must be held by the caller and will remain held on return. * New users should prefer hmm_range_fault_unlocked_timeout() unless they * specifically need to keep the mmap lock held across the call. This helper * cannot support VMAs whose fault handlers need to drop the mmap lock. */ int hmm_range_fault(struct hmm_range *range) { return hmm_range_fault_locked(range, NULL); } EXPORT_SYMBOL(hmm_range_fault); /** * hmm_range_fault_unlocked_timeout - fault in a range with a retry timeout * @range: argument structure * @timeout: timeout in jiffies for internal -EBUSY retries, or 0 to retry * indefinitely * * The caller must not hold the mmap lock. The function takes the mmap read * lock internally and allows handle_mm_fault() to drop it during faults. If * the mmap lock is dropped or the range is invalidated, the function refreshes * range->notifier_seq and restarts the walk internally. * * Passing 0 for @timeout retries indefinitely. A non-zero @timeout is a caller * policy limit for repeated mmu-notifier invalidation retries. HMM does not * interrupt page fault handling when the timeout expires, but returns -EBUSY * if the retry budget is exhausted before a stable range is obtained. * * Returns 0 on success or one of the error codes documented for * hmm_range_fault(). -EINTR is returned if mmap_lock acquisition is * interrupted or a fatal signal is pending during retry handling. */ int hmm_range_fault_unlocked_timeout(struct hmm_range *range, unsigned long timeout) { struct mm_struct *mm = range->notifier->mm; unsigned long deadline = 0; bool locked = false; int ret; do { /* * If the previous fault dropped mmap_lock, then the fault * handler made progress. Restart the retry timeout in that * case, but keep the existing deadline for ordinary -EBUSY * retries. */ if (timeout && !locked) deadline = jiffies + timeout; range->notifier_seq = mmu_interval_read_begin(range->notifier); ret = mmap_read_lock_killable(mm); if (ret) return ret; if (check_stable_address_space(mm)) { mmap_read_unlock(mm); return -EFAULT; } if (timeout && time_after(jiffies, deadline)) { mmap_read_unlock(mm); return -EBUSY; } locked = true; ret = hmm_range_fault_locked(range, &locked); if (locked) mmap_read_unlock(mm); } while (ret == -EBUSY); return ret; } EXPORT_SYMBOL(hmm_range_fault_unlocked_timeout); /** * hmm_dma_map_alloc - Allocate HMM map structure * @dev: device to allocate structure for * @map: HMM map to allocate * @nr_entries: number of entries in the map * @dma_entry_size: size of the DMA entry in the map * * Allocate the HMM map structure and all the lists it contains. * Return 0 on success, -ENOMEM on failure. */ int hmm_dma_map_alloc(struct device *dev, struct hmm_dma_map *map, size_t nr_entries, size_t dma_entry_size) { bool dma_need_sync = false; bool use_iova; WARN_ON_ONCE(!(nr_entries * PAGE_SIZE / dma_entry_size)); /* * The HMM API violates our normal DMA buffer ownership rules and can't * transfer buffer ownership. The dma_addressing_limited() check is a * best approximation to ensure no swiotlb buffering happens. */ #ifdef CONFIG_DMA_NEED_SYNC dma_need_sync = !dev_dma_skip_sync(dev); #endif /* CONFIG_DMA_NEED_SYNC */ if (dma_need_sync || dma_addressing_limited(dev)) return -EOPNOTSUPP; map->dma_entry_size = dma_entry_size; map->pfn_list = kvcalloc(nr_entries, sizeof(*map->pfn_list), GFP_KERNEL | __GFP_NOWARN); if (!map->pfn_list) return -ENOMEM; use_iova = dma_iova_try_alloc(dev, &map->state, 0, nr_entries * PAGE_SIZE); if (!use_iova && dma_need_unmap(dev)) { map->dma_list = kvzalloc_objs(*map->dma_list, nr_entries, GFP_KERNEL | __GFP_NOWARN); if (!map->dma_list) goto err_dma; } return 0; err_dma: kvfree(map->pfn_list); return -ENOMEM; } EXPORT_SYMBOL_GPL(hmm_dma_map_alloc); /** * hmm_dma_map_free - iFree HMM map structure * @dev: device to free structure from * @map: HMM map containing the various lists and state * * Free the HMM map structure and all the lists it contains. */ void hmm_dma_map_free(struct device *dev, struct hmm_dma_map *map) { if (dma_use_iova(&map->state)) dma_iova_free(dev, &map->state); kvfree(map->pfn_list); kvfree(map->dma_list); } EXPORT_SYMBOL_GPL(hmm_dma_map_free); /** * hmm_dma_map_pfn - Map a physical HMM page to DMA address * @dev: Device to map the page for * @map: HMM map * @idx: Index into the PFN and dma address arrays * @p2pdma_state: PCI P2P state. * * dma_alloc_iova() allocates IOVA based on the size specified by their use in * iova->size. Call this function after IOVA allocation to link whole @page * to get the DMA address. Note that very first call to this function * will have @offset set to 0 in the IOVA space allocated from * dma_alloc_iova(). For subsequent calls to this function on same @iova, * @offset needs to be advanced by the caller with the size of previous * page that was linked + DMA address returned for the previous page that was * linked by this function. */ dma_addr_t hmm_dma_map_pfn(struct device *dev, struct hmm_dma_map *map, size_t idx, struct pci_p2pdma_map_state *p2pdma_state) { struct dma_iova_state *state = &map->state; dma_addr_t *dma_addrs = map->dma_list; unsigned long *pfns = map->pfn_list; struct page *page = hmm_pfn_to_page(pfns[idx]); phys_addr_t paddr = hmm_pfn_to_phys(pfns[idx]); size_t offset = idx * map->dma_entry_size; unsigned long attrs = DMA_ATTR_REQUIRE_COHERENT; dma_addr_t dma_addr; int ret; if ((pfns[idx] & HMM_PFN_DMA_MAPPED) && !(pfns[idx] & HMM_PFN_P2PDMA_BUS)) { /* * We are in this flow when there is a need to resync flags, * for example when page was already linked in prefetch call * with READ flag and now we need to add WRITE flag * * This page was already programmed to HW and we don't want/need * to unlink and link it again just to resync flags. */ if (dma_use_iova(state)) return state->addr + offset; /* * Without dma_need_unmap, the dma_addrs array is NULL, thus we * need to regenerate the address below even if there already * was a mapping. But !dma_need_unmap implies that the * mapping stateless, so this is fine. */ if (dma_need_unmap(dev)) return dma_addrs[idx]; /* Continue to remapping */ } switch (pci_p2pdma_state(p2pdma_state, dev, page)) { case PCI_P2PDMA_MAP_NONE: break; case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: attrs |= DMA_ATTR_MMIO; pfns[idx] |= HMM_PFN_P2PDMA; break; case PCI_P2PDMA_MAP_BUS_ADDR: pfns[idx] |= HMM_PFN_P2PDMA_BUS | HMM_PFN_DMA_MAPPED; return pci_p2pdma_bus_addr_map(p2pdma_state->mem, paddr); default: return DMA_MAPPING_ERROR; } if (dma_use_iova(state)) { ret = dma_iova_link(dev, state, paddr, offset, map->dma_entry_size, DMA_BIDIRECTIONAL, attrs); if (ret) goto error; ret = dma_iova_sync(dev, state, offset, map->dma_entry_size); if (ret) { dma_iova_unlink(dev, state, offset, map->dma_entry_size, DMA_BIDIRECTIONAL, attrs); goto error; } dma_addr = state->addr + offset; } else { if (WARN_ON_ONCE(dma_need_unmap(dev) && !dma_addrs)) goto error; dma_addr = dma_map_phys(dev, paddr, map->dma_entry_size, DMA_BIDIRECTIONAL, attrs); if (dma_mapping_error(dev, dma_addr)) goto error; if (dma_need_unmap(dev)) dma_addrs[idx] = dma_addr; } pfns[idx] |= HMM_PFN_DMA_MAPPED; return dma_addr; error: pfns[idx] &= ~HMM_PFN_P2PDMA; return DMA_MAPPING_ERROR; } EXPORT_SYMBOL_GPL(hmm_dma_map_pfn); /** * hmm_dma_unmap_pfn - Unmap a physical HMM page from DMA address * @dev: Device to unmap the page from * @map: HMM map * @idx: Index of the PFN to unmap * * Returns true if the PFN was mapped and has been unmapped, false otherwise. */ bool hmm_dma_unmap_pfn(struct device *dev, struct hmm_dma_map *map, size_t idx) { const unsigned long valid_dma = HMM_PFN_VALID | HMM_PFN_DMA_MAPPED; struct dma_iova_state *state = &map->state; dma_addr_t *dma_addrs = map->dma_list; unsigned long *pfns = map->pfn_list; unsigned long attrs = DMA_ATTR_REQUIRE_COHERENT; if ((pfns[idx] & valid_dma) != valid_dma) return false; if (pfns[idx] & HMM_PFN_P2PDMA) attrs |= DMA_ATTR_MMIO; if (pfns[idx] & HMM_PFN_P2PDMA_BUS) ; /* no need to unmap bus address P2P mappings */ else if (dma_use_iova(state)) dma_iova_unlink(dev, state, idx * map->dma_entry_size, map->dma_entry_size, DMA_BIDIRECTIONAL, attrs); else if (dma_need_unmap(dev)) dma_unmap_phys(dev, dma_addrs[idx], map->dma_entry_size, DMA_BIDIRECTIONAL, attrs); pfns[idx] &= ~(HMM_PFN_DMA_MAPPED | HMM_PFN_P2PDMA | HMM_PFN_P2PDMA_BUS); return true; } EXPORT_SYMBOL_GPL(hmm_dma_unmap_pfn);