mm/cma: accept memory of CMA areas reserved at a fixed address

CMA areas allocated from memblock have their memory accepted by
memblock_alloc_range_nid(), but areas reserved at a fixed address with
memblock_reserve() are not.

If a fixed CMA area is requested by the cma=<size>@<base> command line
parameter, it may be in regular RAM and on TDX and SEV-SNP guests it
must be accepted.

Accept the memory of fixed CMA areas as well, so that all CMA areas are
accepted regardless of how they were reserved.

Link: https://lore.kernel.org/20261029-cma-multi-v1-2-2cbced8b5cb7@kernel.org
Fixes: 75d090fd16 ("x86/tdx: Add unaccepted memory support")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Tested-by: Pankaj Gupta <pankaj.gupta@amd.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>

mm/cma.c

@@ -381,6 +381,8 @@ static int __init cma_fixed_reserve(phys_addr_t base, phys_addr_t size)
 		return -EBUSY;
 	}
 
+	accept_memory(base, size);
+
 	return 0;
 }