mm/hugetlb: enable bootmem allocation from CMA areas

If hugetlb_cma_only is enabled, we know that hugetlb pages can only be
allocated from CMA.  Now that there is an interface to do early
reservations from a CMA area (returning memblock memory), it can be used
to allocate hugetlb pages from CMA.

This also allows for doing pre-HVO on these pages (if enabled).

Make sure to initialize the page structures and associated data correctly.
Create a flag to signal that a hugetlb page has been allocated from CMA
to make things a little easier.

Some configurations of powerpc have a special hugetlb bootmem allocator,
so introduce a boolean arch_specific_huge_bootmem_alloc that returns true
if such an allocator is present.  In that case, CMA bootmem allocations
can't be used, so check that function before trying.

Link: https://lkml.kernel.org/r/20250228182928.2645936-27-fvdl@google.com
Signed-off-by: Frank van der Linden <fvdl@google.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin (Cruise) <roman.gushchin@linux.dev>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index f6b82b0524ed..8f3ac832ee7f 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -591,6 +591,7 @@ enum hugetlb_page_flags {
 	HPG_freed,
 	HPG_vmemmap_optimized,
 	HPG_raw_hwp_unreliable,
+	HPG_cma,
 	__NR_HPAGEFLAGS,
 };
 
@@ -650,6 +651,7 @@ HPAGEFLAG(Temporary, temporary)
 HPAGEFLAG(Freed, freed)
 HPAGEFLAG(VmemmapOptimized, vmemmap_optimized)
 HPAGEFLAG(RawHwpUnreliable, raw_hwp_unreliable)
+HPAGEFLAG(Cma, cma)
 
 #ifdef CONFIG_HUGETLB_PAGE
 
@@ -678,14 +680,18 @@ struct hstate {
 	char name[HSTATE_NAME_LEN];
 };
 
+struct cma;
+
 struct huge_bootmem_page {
 	struct list_head list;
 	struct hstate *hstate;
 	unsigned long flags;
+	struct cma *cma;
 };
 
 #define HUGE_BOOTMEM_HVO		0x0001
 #define HUGE_BOOTMEM_ZONES_VALID	0x0002
+#define HUGE_BOOTMEM_CMA		0x0004
 
 bool hugetlb_bootmem_page_zones_valid(int nid, struct huge_bootmem_page *m);
 
@@ -824,6 +830,17 @@ static inline pte_t arch_make_huge_pte(pte_t entry, unsigned int shift,
 }
 #endif
 
+#ifndef arch_has_huge_bootmem_alloc
+/*
+ * Some architectures do their own bootmem allocation, so they can't use
+ * early CMA allocation.
+ */
+static inline bool arch_has_huge_bootmem_alloc(void)
+{
+	return false;
+}
+#endif
+
 static inline struct hstate *folio_hstate(struct folio *folio)
 {
 	VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio);