mm/cma: introduce a cma validate function

Define a function to check if a CMA area is valid, which means: do its
ranges not cross any zone boundaries.  Store the result in the newly
created flags for each CMA area, so that multiple calls are dealt with.

This allows for checking the validity of a CMA area early, which is needed
later in order to be able to allocate hugetlb bootmem pages from it with
pre-HVO.

Link: https://lkml.kernel.org/r/20250228182928.2645936-24-fvdl@google.com
Signed-off-by: Frank van der Linden <fvdl@google.com>
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: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
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, 7 insertions, 1 deletions

diff --git a/mm/cma.h b/mm/cma.h
index ff79dba5508c..bddc84b3cd96 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -49,11 +49,17 @@ struct cma {
 	/* kobject requires dynamic object */
 	struct cma_kobject *cma_kobj;
 #endif
-	bool reserve_pages_on_error;
+	unsigned long flags;
 	/* NUMA node (NUMA_NO_NODE if unspecified) */
 	int nid;
 };
 
+enum cma_flags {
+	CMA_RESERVE_PAGES_ON_ERROR,
+	CMA_ZONES_VALID,
+	CMA_ZONES_INVALID,
+};
+
 extern struct cma cma_areas[MAX_CMA_AREAS];
 extern unsigned int cma_area_count;