mhp_supports_memmap_on_memory is meant to be used by the caller prior to hot-adding memory in order to figure out whether it can enable MHP_MEMMAP_ON_MEMORY or not.
Enabling MHP_MEMMAP_ON_MEMORY requires: - CONFIG_SPARSEMEM_VMEMMAP - architecture support for altmap - hot-added range spans a single memory block At the moment, only three architectures support passing altmap when building the page tables: x86, POWERPC and ARM. Define an arch_support_memmap_on_memory function on those architectures that returns true, and define a __weak variant of it that will be used on the others. Signed-off-by: Oscar Salvador <[email protected]> --- arch/arm64/mm/mmu.c | 5 +++++ arch/powerpc/mm/mem.c | 5 +++++ arch/x86/mm/init_64.c | 5 +++++ mm/memory_hotplug.c | 24 ++++++++++++++++++++++++ 4 files changed, 39 insertions(+) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index ca692a815731..0da4e4f8794f 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1456,6 +1456,11 @@ static bool inside_linear_region(u64 start, u64 size) (start + size - 1) <= __pa(PAGE_END - 1); } +bool arch_support_memmap_on_memory(void) +{ + return true; +} + int arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) { diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 3fc325bebe4d..18e7e28fe713 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -121,6 +121,11 @@ static void flush_dcache_range_chunked(unsigned long start, unsigned long stop, } } +bool arch_support_memmap_on_memory(void) +{ + return true; +} + int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) { diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index b5a3fa4033d3..ffb9d87c77e8 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -860,6 +860,11 @@ int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages, return ret; } +bool arch_support_memmap_on_memory(void) +{ + return true; +} + int arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) { diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 87fbc2cc0d90..10255606ff85 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1028,6 +1028,20 @@ static int online_memory_block(struct memory_block *mem, void *arg) return device_online(&mem->dev); } +bool __weak arch_support_memmap_on_memory(void) +{ + return false; +} + +bool mhp_supports_memmap_on_memory(unsigned long size) +{ + if (!arch_support_memmap_on_memory() || + !IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP) || + size > memory_block_size_bytes()) + return false; + return true; +} + /* * NOTE: The caller must call lock_device_hotplug() to serialize hotplug * and online/offline operations (triggered e.g. by sysfs). @@ -1064,6 +1078,16 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) goto error; new_node = ret; + /* + * Return -EINVAL if caller specified MHP_MEMMAP_ON_MEMORY and we do + * not support it. + */ + if ((mhp_flags & MHP_MEMMAP_ON_MEMORY) && + !mhp_supports_memmap_on_memory(size)) { + ret = -EINVAL; + goto error; + } + /* * Self hosted memmap array */ -- 2.26.2
