@@ -157,6 +157,7 @@ config PPC
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select ARCH_KEEP_MEMBLOCK
+ select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE if PPC_RADIX_MMU
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_MIGHT_HAVE_PC_SERIO
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
@@ -161,6 +161,30 @@ static inline pgtable_t pmd_pgtable(pmd_t pmd)
int __meminit vmemmap_populated(unsigned long vmemmap_addr, int vmemmap_map_size);
bool altmap_cross_boundary(struct vmem_altmap *altmap, unsigned long start,
unsigned long page_size);
+/*
+ * mm/memory_hotplug.c:mhp_supports_memmap_on_memory goes into details
+ * some of the restrictions. We don't check for PMD_SIZE because our
+ * vmemmap allocation code can fallback correctly. The pageblock
+ * alignment requirement is met using altmap->reserve blocks.
+ */
+#define arch_supports_memmap_on_memory arch_supports_memmap_on_memory
+static inline bool arch_supports_memmap_on_memory(unsigned long size)
+{
+ unsigned long nr_pages = size >> PAGE_SHIFT;
+ unsigned long vmemmap_size = nr_pages * sizeof(struct page);
+
+ if (!radix_enabled())
+ return false;
+ /*
+ * With 4K page size and 2M PMD_SIZE, we can align
+ * things better with memory block size value
+ * starting from 128MB. Hence align things with PMD_SIZE.
+ */
+ if (IS_ENABLED(CONFIG_PPC_4K_PAGES))
+ return IS_ALIGNED(vmemmap_size, PMD_SIZE);
+ return true;
+}
+
#endif /* CONFIG_PPC64 */
#endif /* __ASSEMBLY__ */
@@ -617,6 +617,7 @@ static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index)
static int dlpar_add_lmb(struct drmem_lmb *lmb)
{
+ mhp_t mhp_flags = MHP_NONE | MHP_MEMMAP_ON_MEMORY;
unsigned long block_sz;
int nid, rc;
@@ -637,7 +638,7 @@ static int dlpar_add_lmb(struct drmem_lmb *lmb)
nid = first_online_node;
/* Add the memory */
- rc = __add_memory(nid, lmb->base_addr, block_sz, MHP_NONE);
+ rc = __add_memory(nid, lmb->base_addr, block_sz, mhp_flags);
if (rc) {
invalidate_lmb_associativity_index(lmb);
return rc;
Radix vmemmap mapping can map things correctly at the PMD level or PTE level based on different device boundary checks. Hence we skip the restrictions w.r.t vmemmap size to be multiple of PMD_SIZE. This also makes the feature widely useful because to use PMD_SIZE vmemmap area we require a memory block size of 2GiB We can also use MHP_RESERVE_PAGES_MEMMAP_ON_MEMORY to that the feature can work with a memory block size of 256MB. Using altmap.reserve feature to align things correctly at pageblock granularity. We can end up losing some pages in memory with this. For ex: with a 256MiB memory block size, we require 4 pages to map vmemmap pages, In order to align things correctly we end up adding a reserve of 28 pages. ie, for every 4096 pages 28 pages get reserved. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> --- arch/powerpc/Kconfig | 1 + arch/powerpc/include/asm/pgtable.h | 24 +++++++++++++++++++ .../platforms/pseries/hotplug-memory.c | 3 ++- 3 files changed, 27 insertions(+), 1 deletion(-)