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-rw-r--r--include/linux/hmm.h125
1 files changed, 5 insertions, 120 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index ddf9f7144c43..7475051100c7 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -3,58 +3,8 @@
* Copyright 2013 Red Hat Inc.
*
* Authors: Jérôme Glisse <jglisse@redhat.com>
- */
-/*
- * Heterogeneous Memory Management (HMM)
- *
- * See Documentation/vm/hmm.rst for reasons and overview of what HMM is and it
- * is for. Here we focus on the HMM API description, with some explanation of
- * the underlying implementation.
- *
- * Short description: HMM provides a set of helpers to share a virtual address
- * space between CPU and a device, so that the device can access any valid
- * address of the process (while still obeying memory protection). HMM also
- * provides helpers to migrate process memory to device memory, and back. Each
- * set of functionality (address space mirroring, and migration to and from
- * device memory) can be used independently of the other.
- *
- *
- * HMM address space mirroring API:
- *
- * Use HMM address space mirroring if you want to mirror a range of the CPU
- * page tables of a process into a device page table. Here, "mirror" means "keep
- * synchronized". Prerequisites: the device must provide the ability to write-
- * protect its page tables (at PAGE_SIZE granularity), and must be able to
- * recover from the resulting potential page faults.
- *
- * HMM guarantees that at any point in time, a given virtual address points to
- * either the same memory in both CPU and device page tables (that is: CPU and
- * device page tables each point to the same pages), or that one page table (CPU
- * or device) points to no entry, while the other still points to the old page
- * for the address. The latter case happens when the CPU page table update
- * happens first, and then the update is mirrored over to the device page table.
- * This does not cause any issue, because the CPU page table cannot start
- * pointing to a new page until the device page table is invalidated.
- *
- * HMM uses mmu_notifiers to monitor the CPU page tables, and forwards any
- * updates to each device driver that has registered a mirror. It also provides
- * some API calls to help with taking a snapshot of the CPU page table, and to
- * synchronize with any updates that might happen concurrently.
*
- *
- * HMM migration to and from device memory:
- *
- * HMM provides a set of helpers to hotplug device memory as ZONE_DEVICE, with
- * a new MEMORY_DEVICE_PRIVATE type. This provides a struct page for each page
- * of the device memory, and allows the device driver to manage its memory
- * using those struct pages. Having struct pages for device memory makes
- * migration easier. Because that memory is not addressable by the CPU it must
- * never be pinned to the device; in other words, any CPU page fault can always
- * cause the device memory to be migrated (copied/moved) back to regular memory.
- *
- * A new migrate helper (migrate_vma()) has been added (see mm/migrate.c) that
- * allows use of a device DMA engine to perform the copy operation between
- * regular system memory and device memory.
+ * See Documentation/vm/hmm.rst for reasons and overview of what HMM is.
*/
#ifndef LINUX_HMM_H
#define LINUX_HMM_H
@@ -74,7 +24,6 @@
* 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 provides a flags array for mapping page protections to device
* PTE bits. If the driver valid bit for an entry is bit 3,
@@ -86,7 +35,6 @@
enum hmm_pfn_flag_e {
HMM_PFN_VALID = 0,
HMM_PFN_WRITE,
- HMM_PFN_DEVICE_PRIVATE,
HMM_PFN_FLAG_MAX
};
@@ -122,9 +70,6 @@ enum hmm_pfn_value_e {
*
* @notifier: a mmu_interval_notifier that includes the start/end
* @notifier_seq: result of mmu_interval_read_begin()
- * @hmm: the core HMM structure this range is active against
- * @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)
@@ -132,8 +77,8 @@ enum hmm_pfn_value_e {
* @values: pfn value for some special case (none, special, error, ...)
* @default_flags: default flags for the range (write, read, ... see hmm doc)
* @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
- * @pfn_shifts: pfn shift value (should be <= PAGE_SHIFT)
- * @valid: pfns array did not change since it has been fill by an HMM function
+ * @pfn_shift: pfn shift value (should be <= PAGE_SHIFT)
+ * @dev_private_owner: owner of device private pages
*/
struct hmm_range {
struct mmu_interval_notifier *notifier;
@@ -146,6 +91,7 @@ struct hmm_range {
uint64_t default_flags;
uint64_t pfn_flags_mask;
uint8_t pfn_shift;
+ void *dev_private_owner;
};
/*
@@ -172,70 +118,9 @@ static inline struct page *hmm_device_entry_to_page(const struct hmm_range *rang
}
/*
- * hmm_device_entry_to_pfn() - return pfn value store in a device entry
- * @range: range use to decode device entry value
- * @entry: device entry to extract pfn from
- * Return: pfn value if device entry is valid, -1UL otherwise
- */
-static inline unsigned long
-hmm_device_entry_to_pfn(const struct hmm_range *range, uint64_t pfn)
-{
- 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;
- if (!(pfn & range->flags[HMM_PFN_VALID]))
- return -1UL;
- return (pfn >> range->pfn_shift);
-}
-
-/*
- * hmm_device_entry_from_page() - create a valid device entry for a page
- * @range: range use to encode HMM pfn value
- * @page: page for which to create the device entry
- * Return: valid device entry for the page
- */
-static inline uint64_t hmm_device_entry_from_page(const struct hmm_range *range,
- struct page *page)
-{
- return (page_to_pfn(page) << range->pfn_shift) |
- range->flags[HMM_PFN_VALID];
-}
-
-/*
- * hmm_device_entry_from_pfn() - create a valid device entry value from pfn
- * @range: range use to encode HMM pfn value
- * @pfn: pfn value for which to create the device entry
- * Return: valid device entry for the pfn
- */
-static inline uint64_t hmm_device_entry_from_pfn(const struct hmm_range *range,
- unsigned long pfn)
-{
- return (pfn << range->pfn_shift) |
- range->flags[HMM_PFN_VALID];
-}
-
-/*
- * Retry fault if non-blocking, drop mmap_sem and return -EAGAIN in that case.
- */
-#define HMM_FAULT_ALLOW_RETRY (1 << 0)
-
-/* Don't fault in missing PTEs, just snapshot the current state. */
-#define HMM_FAULT_SNAPSHOT (1 << 1)
-
-#ifdef CONFIG_HMM_MIRROR
-/*
* Please see Documentation/vm/hmm.rst for how to use the range API.
*/
-long hmm_range_fault(struct hmm_range *range, unsigned int flags);
-#else
-static inline long hmm_range_fault(struct hmm_range *range, unsigned int flags)
-{
- return -EOPNOTSUPP;
-}
-#endif
+long hmm_range_fault(struct hmm_range *range);
/*
* HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range