x86/numa: Add Devicetree support

Hyper-V has usecases where it needs to fetch NUMA information from
Devicetree. Currently, it is not possible to extract the NUMA information
from Devicetree for the x86 arch.

Add support for Devicetree in the x86_numa_init() function, allowing the
retrieval of NUMA node information from the Devicetree.
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/1692949657-16446-2-git-send-email-ssengar@linux.microsoft.com

arch/x86/Kconfig

@@ -1534,6 +1534,7 @@ config NUMA
 	depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
 	default y if X86_BIGSMP
 	select USE_PERCPU_NUMA_NODE_ID
+	select OF_NUMA if OF
 	help
 	  Enable NUMA (Non-Uniform Memory Access) support.
 

arch/x86/mm/numa.c

@@ -3,6 +3,7 @@
 #include <linux/acpi.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
+#include <linux/of.h>
 #include <linux/string.h>
 #include <linux/init.h>
 #include <linux/memblock.h>
@@ -733,6 +734,8 @@ void __init x86_numa_init(void)
 		if (!numa_init(amd_numa_init))
 			return;
 #endif
+		if (acpi_disabled && !numa_init(of_numa_init))
+			return;
 	}
 
 	numa_init(dummy_numa_init);