diff options
Diffstat (limited to 'mm/hmm.c')
| -rw-r--r-- | mm/hmm.c | 24 |
1 files changed, 17 insertions, 7 deletions
@@ -38,6 +38,18 @@ enum { HMM_NEED_ALL_BITS = HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT, }; +/* + * 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 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]; +} + static int hmm_pfns_fill(unsigned long addr, unsigned long end, struct hmm_range *range, enum hmm_pfn_value_e value) { @@ -544,7 +556,7 @@ static const struct mm_walk_ops hmm_walk_ops = { /** * hmm_range_fault - try to fault some address in a virtual address range - * @range: range being faulted + * @range: argument structure * @flags: HMM_FAULT_* flags * * Return: the number of valid pages in range->pfns[] (from range start @@ -558,13 +570,11 @@ static const struct mm_walk_ops hmm_walk_ops = { * only). * -EBUSY: The range has been invalidated and the caller needs to wait for * the invalidation to finish. - * -EFAULT: Invalid (i.e., either no valid vma or it is illegal to access - * that range) number of valid pages in range->pfns[] (from - * range start address). + * -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 a regular CPU page fault except that it will not trigger - * any memory migration if the memory being faulted is not accessible by CPUs - * and caller does not ask for migration. + * This is similar to get_user_pages(), except that it can read the page tables + * without mutating them (ie causing faults). * * On error, for one virtual address in the range, the function will mark the * corresponding HMM pfn entry with an error flag. |