Keeping last-level mappings is interesting on some architectures as it allows mapping/unmapping pages from the kernel direct map without the risk of splitting blocks which, under the break-before-make rule, may trigger page-faults the kernel can't handle.
However, mapping the entire direct map at PTE-level is costly. So instead, create a new memblock flag MEMBLOCK_LLMAP to enable the system to decide which region must be covered by mappings up to the last-level.
Signed-off-by: Vincent Donnefort vdonnefort@google.com
diff --git a/include/linux/memblock.h b/include/linux/memblock.h index d62db9e776cf..d40a5ded188d 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -52,6 +52,7 @@ extern unsigned long long max_possible_pfn; * kernel that we know is good to use. It is the only memory that * allocations may happen from in this phase. * @MEMBLOCK_RSRV_HUGETLB: memory is reserved for hugetlb pages + * @MEMBLOCK_LLMAP: memory region to be mapped using last-level mapping */ enum memblock_flags { MEMBLOCK_NONE = 0x0, /* No special request */ @@ -63,6 +64,7 @@ enum memblock_flags { MEMBLOCK_RSRV_KERN = 0x20, /* memory reserved for kernel use */ MEMBLOCK_KHO_SCRATCH = 0x40, /* scratch memory for kexec handover */ MEMBLOCK_RSRV_HUGETLB = 0x80, /* memory reserved for hugetlb pages */ + MEMBLOCK_LLMAP = 0x100,/* last-level mapping */ };
/** @@ -160,6 +162,8 @@ int memblock_reserved_mark_noinit(phys_addr_t base, phys_addr_t size); int memblock_reserved_mark_kern(phys_addr_t base, phys_addr_t size); int memblock_mark_kho_scratch(phys_addr_t base, phys_addr_t size); int memblock_clear_kho_scratch(phys_addr_t base, phys_addr_t size); +int memblock_mark_llmap(phys_addr_t base, phys_addr_t size); +int memblock_clear_llmap(phys_addr_t base, phys_addr_t size);
void memblock_free(void *ptr, size_t size); void reset_all_zones_managed_pages(void); @@ -306,6 +310,11 @@ static inline bool memblock_is_kho_scratch(struct memblock_region *m) return m->flags & MEMBLOCK_KHO_SCRATCH; }
+static inline bool memblock_is_llmap(struct memblock_region *m) +{ + return m->flags & MEMBLOCK_LLMAP; +} + int memblock_search_pfn_nid(unsigned long pfn, unsigned long *start_pfn, unsigned long *end_pfn); void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn, diff --git a/mm/memblock.c b/mm/memblock.c index 9ce86349a29f..1591b50503ed 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1119,6 +1119,16 @@ int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size) */ int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size) { + struct memblock_region *r; + + memblock_cap_size(base, &size); + + for_each_mem_region(r) { + if (memblock_is_llmap(r) && + memblock_addrs_overlap(base, size, r->base, r->size)) + return -EINVAL; + } + return memblock_setclr_flag(&memblock.memory, base, size, 1, MEMBLOCK_NOMAP); }
@@ -1204,6 +1214,45 @@ __init int memblock_clear_kho_scratch(phys_addr_t base, phys_addr_t size) MEMBLOCK_KHO_SCRATCH); }
+/** + * memblock_mark_llmap - Mark a memory region with flag MEMBLOCK_LLMAP. + * @base: the base phys addr of the region + * @size: the size of the region + * + * If supported by the architecture, such region is mapped at the last-level in + * the kernel direct map. + * + * Return: 0 on success, -errno on failure. + */ +int __init_memblock memblock_mark_llmap(phys_addr_t base, phys_addr_t size) +{ + struct memblock_region *r; + + memblock_cap_size(base, &size); + + for_each_mem_region(r) { + if (memblock_is_nomap(r) && + memblock_addrs_overlap(base, size, r->base, r->size)) + return -EINVAL; + } + + return memblock_setclr_flag(&memblock.memory, base, size, 1, + MEMBLOCK_LLMAP); +} + +/** + * memblock_clear_llmap - Clear flag MEMBLOCK_LLMAP for a specified region. + * @base: the base phys addr of the region + * @size: the size of the region + * + * Return: 0 on success, -errno on failure. + */ +int __init_memblock memblock_clear_llmap(phys_addr_t base, phys_addr_t size) +{ + return memblock_setclr_flag(&memblock.memory, base, size, 0, + MEMBLOCK_LLMAP); +} + static bool should_skip_region(struct memblock_type *type, struct memblock_region *m, int nid, int flags) @@ -2886,6 +2935,7 @@ static const char * const flagname[] = { [ilog2(MEMBLOCK_RSRV_NOINIT)] = "RSV_NIT", [ilog2(MEMBLOCK_RSRV_KERN)] = "RSV_KERN", [ilog2(MEMBLOCK_KHO_SCRATCH)] = "KHO_SCRATCH", + [ilog2(MEMBLOCK_LLMAP)] = "LLMAP", };
static int memblock_debug_show(struct seq_file *m, void *private)