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Diffstat (limited to 'mm/hmm.c')
| -rw-r--r-- | mm/hmm.c | 895 |
1 files changed, 895 insertions, 0 deletions
diff --git a/mm/hmm.c b/mm/hmm.c new file mode 100644 index 000000000000..4ec74c18bef6 --- /dev/null +++ b/mm/hmm.c @@ -0,0 +1,895 @@ +// 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/hmm-dma.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/leafops.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/pci-p2pdma.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, +}; + +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_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; +} + +#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_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] &= 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_vma_fault(addr, end, required_fault, walk); +} + +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION +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_vma_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_ENABLE_THP_MIGRATION */ + +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_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] &= 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) { + 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] &= 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_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); + +/** + * 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; +#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 = kvcalloc(nr_entries, sizeof(*map->dma_list), + 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 = 0; + 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 = 0; + + 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); |