mm/hmm: use device driver encoding for HMM pfn (f88a1e90) · Commits · 戴 / test

include/linux/hmm.h

+94 −36

Original line number	Diff line number	Diff line
		@@ -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];
		}


		@@ -263,25 +340,6 @@ int hmm_mirror_register(struct hmm_mirror mirror, struct mm_struct mm);
		void hmm_mirror_unregister(struct hmm_mirror *mirror);


		/*
		* 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

mm/hmm.c

+58 −41

Original line number	Diff line number	Diff line
		@@ -306,6 +306,7 @@ static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
		{
		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_walk *walk, unsigned long addr,
		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 addr,

		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 long addr, unsigned long end,
		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(const struct hmm_vma_walk *hmm_vma_walk,
		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 long addr, unsigned long end,
		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_walk *walk,
		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_walk *walk,
		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_walk *walk, unsigned long addr,
		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_walk *walk, unsigned long addr,
		* 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_walk *walk, unsigned long addr,
		}

		/* 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_range *range)
		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 *range)
		* 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 *range, bool block)

		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 *range, bool block)
		* 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 *range, bool block)
		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;

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