From: Jérôme Glisse <jglisse@xxxxxxxxxx> Subject: mm/hmm: use device driver encoding for HMM pfn Users of hmm_vma_fault() and hmm_vma_get_pfns() provide a flags array and pfn shift value allowing them to define their own encoding for HMM pfn that are fill inside the pfns array of the hmm_range struct. With this device driver can get pfn that match their own private encoding out of HMM without having to do any conversion. [rcampbell@xxxxxxxxxx: don't ignore specific pte fault flag in hmm_vma_fault()] Link: http://lkml.kernel.org/r/20180326213009.2460-2-jglisse@xxxxxxxxxx [rcampbell@xxxxxxxxxx: clarify fault logic for device private memory] Link: http://lkml.kernel.org/r/20180326213009.2460-3-jglisse@xxxxxxxxxx Link: http://lkml.kernel.org/r/20180323005527.758-16-jglisse@xxxxxxxxxx Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx> Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx> Cc: Evgeny Baskakov <ebaskakov@xxxxxxxxxx> Cc: Ralph Campbell <rcampbell@xxxxxxxxxx> Cc: Mark Hairgrove <mhairgrove@xxxxxxxxxx> Cc: John Hubbard <jhubbard@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/hmm.h | 130 ++++++++++++++++++++++++++++++------------ mm/hmm.c | 99 ++++++++++++++++++------------- 2 files changed, 152 insertions(+), 77 deletions(-) diff -puN include/linux/hmm.h~mm-hmm-use-device-driver-encoding-for-hmm-pfn-v2 include/linux/hmm.h --- a/include/linux/hmm.h~mm-hmm-use-device-driver-encoding-for-hmm-pfn-v2 +++ a/include/linux/hmm.h @@ -80,68 +80,145 @@ struct hmm; /* + * hmm_pfn_flag_e - HMM flag enums + * * Flags: * HMM_PFN_VALID: pfn is valid. It has, at least, read permission. * HMM_PFN_WRITE: CPU page table has write permission set + * HMM_PFN_DEVICE_PRIVATE: private device memory (ZONE_DEVICE) + * + * The driver provide a flags array, if driver valid bit for an entry is bit + * 3 ie (entry & (1 << 3)) is true if entry is valid then driver must provide + * an array in hmm_range.flags with hmm_range.flags[HMM_PFN_VALID] == 1 << 3. + * Same logic apply to all flags. This is same idea as vm_page_prot in vma + * except that this is per device driver rather than per architecture. + */ +enum hmm_pfn_flag_e { + HMM_PFN_VALID = 0, + HMM_PFN_WRITE, + HMM_PFN_DEVICE_PRIVATE, + HMM_PFN_FLAG_MAX +}; + +/* + * hmm_pfn_value_e - HMM pfn special value + * + * Flags: * HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory + * HMM_PFN_NONE: corresponding CPU page table entry is pte_none() * HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the * result of vm_insert_pfn() or vm_insert_page(). Therefore, it should not * be mirrored by a device, because the entry will never have HMM_PFN_VALID * set and the pfn value is undefined. - * HMM_PFN_DEVICE_PRIVATE: unaddressable device memory (ZONE_DEVICE) + * + * Driver provide entry value for none entry, error entry and special entry, + * driver can alias (ie use same value for error and special for instance). It + * should not alias none and error or special. + * + * HMM pfn value returned by hmm_vma_get_pfns() or hmm_vma_fault() will be: + * hmm_range.values[HMM_PFN_ERROR] if CPU page table entry is poisonous, + * hmm_range.values[HMM_PFN_NONE] if there is no CPU page table + * hmm_range.values[HMM_PFN_SPECIAL] if CPU page table entry is a special one */ -#define HMM_PFN_VALID (1 << 0) -#define HMM_PFN_WRITE (1 << 1) -#define HMM_PFN_ERROR (1 << 2) -#define HMM_PFN_SPECIAL (1 << 3) -#define HMM_PFN_DEVICE_PRIVATE (1 << 4) -#define HMM_PFN_SHIFT 5 +enum hmm_pfn_value_e { + HMM_PFN_ERROR, + HMM_PFN_NONE, + HMM_PFN_SPECIAL, + HMM_PFN_VALUE_MAX +}; + +/* + * struct hmm_range - track invalidation lock on virtual address range + * + * @vma: the vm area struct for the range + * @list: all range lock are on a list + * @start: range virtual start address (inclusive) + * @end: range virtual end address (exclusive) + * @pfns: array of pfns (big enough for the range) + * @flags: pfn flags to match device driver page table + * @values: pfn value for some special case (none, special, error, ...) + * @pfn_shifts: pfn shift value (should be <= PAGE_SHIFT) + * @valid: pfns array did not change since it has been fill by an HMM function + */ +struct hmm_range { + struct vm_area_struct *vma; + struct list_head list; + unsigned long start; + unsigned long end; + uint64_t *pfns; + const uint64_t *flags; + const uint64_t *values; + uint8_t pfn_shift; + bool valid; +}; /* * hmm_pfn_to_page() - return struct page pointed to by a valid HMM pfn + * @range: range use to decode HMM pfn value * @pfn: HMM pfn value to get corresponding struct page from * Returns: struct page pointer if pfn is a valid HMM pfn, NULL otherwise * * If the HMM pfn is valid (ie valid flag set) then return the struct page * matching the pfn value stored in the HMM pfn. Otherwise return NULL. */ -static inline struct page *hmm_pfn_to_page(uint64_t pfn) +static inline struct page *hmm_pfn_to_page(const struct hmm_range *range, + uint64_t pfn) { - if (!(pfn & HMM_PFN_VALID)) + if (pfn == range->values[HMM_PFN_NONE]) + return NULL; + if (pfn == range->values[HMM_PFN_ERROR]) + return NULL; + if (pfn == range->values[HMM_PFN_SPECIAL]) return NULL; - return pfn_to_page(pfn >> HMM_PFN_SHIFT); + if (!(pfn & range->flags[HMM_PFN_VALID])) + return NULL; + return pfn_to_page(pfn >> range->pfn_shift); } /* * hmm_pfn_to_pfn() - return pfn value store in a HMM pfn + * @range: range use to decode HMM pfn value * @pfn: HMM pfn value to extract pfn from * Returns: pfn value if HMM pfn is valid, -1UL otherwise */ -static inline unsigned long hmm_pfn_to_pfn(uint64_t pfn) +static inline unsigned long hmm_pfn_to_pfn(const struct hmm_range *range, + uint64_t pfn) { - if (!(pfn & HMM_PFN_VALID)) + if (pfn == range->values[HMM_PFN_NONE]) + return -1UL; + if (pfn == range->values[HMM_PFN_ERROR]) + return -1UL; + if (pfn == range->values[HMM_PFN_SPECIAL]) return -1UL; - return (pfn >> HMM_PFN_SHIFT); + if (!(pfn & range->flags[HMM_PFN_VALID])) + return -1UL; + return (pfn >> range->pfn_shift); } /* * hmm_pfn_from_page() - create a valid HMM pfn value from struct page + * @range: range use to encode HMM pfn value * @page: struct page pointer for which to create the HMM pfn * Returns: valid HMM pfn for the page */ -static inline uint64_t hmm_pfn_from_page(struct page *page) +static inline uint64_t hmm_pfn_from_page(const struct hmm_range *range, + struct page *page) { - return (page_to_pfn(page) << HMM_PFN_SHIFT) | HMM_PFN_VALID; + return (page_to_pfn(page) << range->pfn_shift) | + range->flags[HMM_PFN_VALID]; } /* * hmm_pfn_from_pfn() - create a valid HMM pfn value from pfn + * @range: range use to encode HMM pfn value * @pfn: pfn value for which to create the HMM pfn * Returns: valid HMM pfn for the pfn */ -static inline uint64_t hmm_pfn_from_pfn(unsigned long pfn) +static inline uint64_t hmm_pfn_from_pfn(const struct hmm_range *range, + unsigned long pfn) { - return (pfn << HMM_PFN_SHIFT) | HMM_PFN_VALID; + return (pfn << range->pfn_shift) | + range->flags[HMM_PFN_VALID]; } @@ -264,25 +341,6 @@ void hmm_mirror_unregister(struct hmm_mi /* - * struct hmm_range - track invalidation lock on virtual address range - * - * @vma: the vm area struct for the range - * @list: all range lock are on a list - * @start: range virtual start address (inclusive) - * @end: range virtual end address (exclusive) - * @pfns: array of pfns (big enough for the range) - * @valid: pfns array did not change since it has been fill by an HMM function - */ -struct hmm_range { - struct vm_area_struct *vma; - struct list_head list; - unsigned long start; - unsigned long end; - uint64_t *pfns; - bool valid; -}; - -/* * To snapshot the CPU page table, call hmm_vma_get_pfns(), then take a device * driver lock that serializes device page table updates, then call * hmm_vma_range_done(), to check if the snapshot is still valid. The same diff -puN mm/hmm.c~mm-hmm-use-device-driver-encoding-for-hmm-pfn-v2 mm/hmm.c --- a/mm/hmm.c~mm-hmm-use-device-driver-encoding-for-hmm-pfn-v2 +++ a/mm/hmm.c @@ -306,6 +306,7 @@ static int hmm_vma_do_fault(struct mm_wa { unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_REMOTE; struct hmm_vma_walk *hmm_vma_walk = walk->private; + struct hmm_range *range = hmm_vma_walk->range; struct vm_area_struct *vma = walk->vma; int r; @@ -315,7 +316,7 @@ static int hmm_vma_do_fault(struct mm_wa if (r & VM_FAULT_RETRY) return -EBUSY; if (r & VM_FAULT_ERROR) { - *pfn = HMM_PFN_ERROR; + *pfn = range->values[HMM_PFN_ERROR]; return -EFAULT; } @@ -333,7 +334,7 @@ static int hmm_pfns_bad(unsigned long ad i = (addr - range->start) >> PAGE_SHIFT; for (; addr < end; addr += PAGE_SIZE, i++) - pfns[i] = HMM_PFN_ERROR; + pfns[i] = range->values[HMM_PFN_ERROR]; return 0; } @@ -362,7 +363,7 @@ static int hmm_vma_walk_hole_(unsigned l hmm_vma_walk->last = addr; i = (addr - range->start) >> PAGE_SHIFT; for (; addr < end; addr += PAGE_SIZE, i++) { - pfns[i] = 0; + pfns[i] = range->values[HMM_PFN_NONE]; if (fault || write_fault) { int ret; @@ -380,24 +381,31 @@ static inline void hmm_pte_need_fault(co uint64_t pfns, uint64_t cpu_flags, bool *fault, bool *write_fault) { + struct hmm_range *range = hmm_vma_walk->range; + *fault = *write_fault = false; if (!hmm_vma_walk->fault) return; /* We aren't ask to do anything ... */ - if (!(pfns & HMM_PFN_VALID)) + if (!(pfns & range->flags[HMM_PFN_VALID])) return; - /* If CPU page table is not valid then we need to fault */ - *fault = cpu_flags & HMM_PFN_VALID; - /* Need to write fault ? */ - if ((pfns & HMM_PFN_WRITE) && !(cpu_flags & HMM_PFN_WRITE)) { - *fault = *write_fault = false; + /* If this is device memory than only fault if explicitly requested */ + if ((cpu_flags & range->flags[HMM_PFN_DEVICE_PRIVATE])) { + /* Do we fault on device memory ? */ + if (pfns & range->flags[HMM_PFN_DEVICE_PRIVATE]) { + *write_fault = pfns & range->flags[HMM_PFN_WRITE]; + *fault = true; + } return; } - /* Do we fault on device memory ? */ - if ((pfns & HMM_PFN_DEVICE_PRIVATE) && - (cpu_flags & HMM_PFN_DEVICE_PRIVATE)) { - *write_fault = pfns & HMM_PFN_WRITE; + + /* If CPU page table is not valid then we need to fault */ + *fault = !(cpu_flags & range->flags[HMM_PFN_VALID]); + /* Need to write fault ? */ + if ((pfns & range->flags[HMM_PFN_WRITE]) && + !(cpu_flags & range->flags[HMM_PFN_WRITE])) { + *write_fault = true; *fault = true; } } @@ -439,13 +447,13 @@ static int hmm_vma_walk_hole(unsigned lo return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk); } -static inline uint64_t pmd_to_hmm_pfn_flags(pmd_t pmd) +static inline uint64_t 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; + return pmd_write(pmd) ? 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, @@ -455,12 +463,13 @@ static int hmm_vma_handle_pmd(struct mm_ 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; - uint64_t flag = 0, cpu_flags; bool fault, write_fault; + uint64_t cpu_flags; npages = (end - addr) >> PAGE_SHIFT; - cpu_flags = pmd_to_hmm_pfn_flags(pmd); + cpu_flags = pmd_to_hmm_pfn_flags(range, pmd); hmm_range_need_fault(hmm_vma_walk, pfns, npages, cpu_flags, &fault, &write_fault); @@ -468,20 +477,19 @@ static int hmm_vma_handle_pmd(struct mm_ return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk); pfn = pmd_pfn(pmd) + pte_index(addr); - flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0; for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) - pfns[i] = hmm_pfn_from_pfn(pfn) | flag; + pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags; hmm_vma_walk->last = end; return 0; } -static inline uint64_t pte_to_hmm_pfn_flags(pte_t pte) +static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte) { if (pte_none(pte) || !pte_present(pte)) return 0; - return pte_write(pte) ? HMM_PFN_VALID | - HMM_PFN_WRITE : - HMM_PFN_VALID; + return pte_write(pte) ? range->flags[HMM_PFN_VALID] | + range->flags[HMM_PFN_WRITE] : + range->flags[HMM_PFN_VALID]; } static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, @@ -489,14 +497,16 @@ static int hmm_vma_handle_pte(struct mm_ uint64_t *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; bool fault, write_fault; uint64_t cpu_flags; pte_t pte = *ptep; + uint64_t orig_pfn = *pfn; - *pfn = 0; - cpu_flags = pte_to_hmm_pfn_flags(pte); - hmm_pte_need_fault(hmm_vma_walk, *pfn, cpu_flags, + *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); if (pte_none(pte)) { @@ -519,11 +529,16 @@ static int hmm_vma_handle_pte(struct mm_ * device and report anything else as error. */ if (is_device_private_entry(entry)) { - cpu_flags = HMM_PFN_VALID | HMM_PFN_DEVICE_PRIVATE; + cpu_flags = range->flags[HMM_PFN_VALID] | + range->flags[HMM_PFN_DEVICE_PRIVATE]; cpu_flags |= is_write_device_private_entry(entry) ? - HMM_PFN_WRITE : 0; - *pfn = hmm_pfn_from_pfn(swp_offset(entry)); - *pfn |= HMM_PFN_DEVICE_PRIVATE; + range->flags[HMM_PFN_WRITE] : 0; + 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, swp_offset(entry)); + *pfn |= cpu_flags; return 0; } @@ -539,14 +554,14 @@ static int hmm_vma_handle_pte(struct mm_ } /* Report error for everything else */ - *pfn = HMM_PFN_ERROR; + *pfn = range->values[HMM_PFN_ERROR]; return -EFAULT; } if (fault || write_fault) goto fault; - *pfn = hmm_pfn_from_pfn(pte_pfn(pte)) | cpu_flags; + *pfn = hmm_pfn_from_pfn(range, pte_pfn(pte)) | cpu_flags; return 0; fault: @@ -615,12 +630,13 @@ again: return 0; } -static void hmm_pfns_clear(uint64_t *pfns, +static void hmm_pfns_clear(struct hmm_range *range, + uint64_t *pfns, unsigned long addr, unsigned long end) { for (; addr < end; addr += PAGE_SIZE, pfns++) - *pfns = 0; + *pfns = range->values[HMM_PFN_NONE]; } static void hmm_pfns_special(struct hmm_range *range) @@ -628,7 +644,7 @@ static void hmm_pfns_special(struct hmm_ unsigned long addr = range->start, i = 0; for (; addr < range->end; addr += PAGE_SIZE, i++) - range->pfns[i] = HMM_PFN_SPECIAL; + range->pfns[i] = range->values[HMM_PFN_SPECIAL]; } /* @@ -681,7 +697,7 @@ int hmm_vma_get_pfns(struct hmm_range *r * write without read access are not supported by HMM, because * operations such has atomic access would not work. */ - hmm_pfns_clear(range->pfns, range->start, range->end); + hmm_pfns_clear(range, range->pfns, range->start, range->end); return -EPERM; } @@ -834,7 +850,7 @@ int hmm_vma_fault(struct hmm_range *rang hmm = hmm_register(vma->vm_mm); if (!hmm) { - hmm_pfns_clear(range->pfns, range->start, range->end); + hmm_pfns_clear(range, range->pfns, range->start, range->end); return -ENOMEM; } /* Caller must have registered a mirror using hmm_mirror_register() */ @@ -854,7 +870,7 @@ int hmm_vma_fault(struct hmm_range *rang * write without read access are not supported by HMM, because * operations such has atomic access would not work. */ - hmm_pfns_clear(range->pfns, range->start, range->end); + hmm_pfns_clear(range, range->pfns, range->start, range->end); return -EPERM; } @@ -887,7 +903,8 @@ int hmm_vma_fault(struct hmm_range *rang unsigned long i; i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT; - hmm_pfns_clear(&range->pfns[i], hmm_vma_walk.last, range->end); + hmm_pfns_clear(range, &range->pfns[i], hmm_vma_walk.last, + range->end); hmm_vma_range_done(range); } return ret; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
