x86/numa_emu: use a helper function to get MAX_DMA32_PFN

This is required to make numa emulation code architecture independent so
that it can be moved to generic code in following commits.

Link: https://lkml.kernel.org/r/20240807064110.1003856-16-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Zi Yan <ziy@nvidia.com> # for x86_64 and arm64
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> [arm64 + CXL via QEMU]
Acked-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Samuel Holland <samuel.holland@sifive.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/x86/include/asm/numa.h

@@ -74,6 +74,7 @@ void debug_cpumask_set_cpu(int cpu, int node, bool enable);
 int numa_emu_cmdline(char *str);
 void __init numa_emu_update_cpu_to_node(int *emu_nid_to_phys,
 					unsigned int nr_emu_nids);
+u64 __init numa_emu_dma_end(void);
 #else /* CONFIG_NUMA_EMU */
 static inline int numa_emu_cmdline(char *str)
 {

arch/x86/mm/numa.c

@@ -872,6 +872,11 @@ void __init numa_emu_update_cpu_to_node(int *emu_nid_to_phys,
 		__apicid_to_node[i] = j < nr_emu_nids ? j : 0;
 	}
 }
+
+u64 __init numa_emu_dma_end(void)
+{
+	return PFN_PHYS(MAX_DMA32_PFN);
+}
 #endif /* CONFIG_NUMA_EMU */
 
 #ifdef CONFIG_NUMA_KEEP_MEMINFO

arch/x86/mm/numa_emulation.c

@@ -128,7 +128,7 @@ static int __init split_nodes_interleave(struct numa_meminfo *ei,
 	 */
 	while (!nodes_empty(physnode_mask)) {
 		for_each_node_mask(i, physnode_mask) {
-			u64 dma32_end = PFN_PHYS(MAX_DMA32_PFN);
+			u64 dma32_end = numa_emu_dma_end();
 			u64 start, limit, end;
 			int phys_blk;
 
@@ -275,7 +275,7 @@ static int __init split_nodes_size_interleave_uniform(struct numa_meminfo *ei,
 	 */
 	while (!nodes_empty(physnode_mask)) {
 		for_each_node_mask(i, physnode_mask) {
-			u64 dma32_end = PFN_PHYS(MAX_DMA32_PFN);
+			u64 dma32_end = numa_emu_dma_end();
 			u64 start, limit, end;
 			int phys_blk;