x86/numa: Fix SRAT lookup of CFMWS ranges with numa_fill_memblks()

For configurations that have the kconfig option NUMA_KEEP_MEMINFO
disabled, numa_fill_memblks() only returns with NUMA_NO_MEMBLK (-1).
SRAT lookup fails then because an existing SRAT memory range cannot be
found for a CFMWS address range. This causes the addition of a
duplicate numa_memblk with a different node id and a subsequent page
fault and kernel crash during boot.

Fix this by making numa_fill_memblks() always available regardless of
NUMA_KEEP_MEMINFO.

As Dan suggested, the fix is implemented to remove numa_fill_memblks()
from sparsemem.h and alos using __weak for the function.

Note that the issue was initially introduced with [1]. But since
phys_to_target_node() was originally used that returned the valid node
0, an additional numa_memblk was not added. Though, the node id was
wrong too, a message is seen then in the logs:

 kernel/numa.c:  pr_info_once("Unknown target node for memory at 0x%llx, assuming node 0\n",

[1] commit fd49f99c18 ("ACPI: NUMA: Add a node and memblk for each
    CFMWS not in SRAT")

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/all/66271b0072317_69102944c@dwillia2-xfh.jf.intel.com.notmuch/
Fixes: 8f10046799 ("ACPI/NUMA: Apply SRAT proximity domain to entire CFMWS window")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/x86/include/asm/sparsemem.h

@@ -37,8 +37,6 @@ extern int phys_to_target_node(phys_addr_t start);
 #define phys_to_target_node phys_to_target_node
 extern int memory_add_physaddr_to_nid(u64 start);
 #define memory_add_physaddr_to_nid memory_add_physaddr_to_nid
-extern int numa_fill_memblks(u64 start, u64 end);
-#define numa_fill_memblks numa_fill_memblks
 #endif
 #endif /* __ASSEMBLY__ */
 

arch/x86/mm/numa.c

@@ -929,6 +929,8 @@ int memory_add_physaddr_to_nid(u64 start)
 }
 EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 
+#endif
+
 static int __init cmp_memblk(const void *a, const void *b)
 {
 	const struct numa_memblk *ma = *(const struct numa_memblk **)a;
@@ -1001,5 +1003,3 @@ int __init numa_fill_memblks(u64 start, u64 end)
 	}
 	return 0;
 }
-
-#endif

drivers/acpi/numa/srat.c

@@ -208,6 +208,11 @@ int __init srat_disabled(void)
 	return acpi_numa < 0;
 }
 
+__weak int __init numa_fill_memblks(u64 start, u64 end)
+{
+	return NUMA_NO_MEMBLK;
+}
+
 #if defined(CONFIG_X86) || defined(CONFIG_ARM64) || defined(CONFIG_LOONGARCH)
 /*
  * Callback for SLIT parsing.  pxm_to_node() returns NUMA_NO_NODE for

include/linux/numa.h

@@ -36,12 +36,7 @@ int memory_add_physaddr_to_nid(u64 start);
 int phys_to_target_node(u64 start);
 #endif
 
-#ifndef numa_fill_memblks
+int numa_fill_memblks(u64 start, u64 end);
-static inline int __init numa_fill_memblks(u64 start, u64 end)
-{
-	return NUMA_NO_MEMBLK;
-}
-#endif
 
 #else /* !CONFIG_NUMA */
 static inline int numa_nearest_node(int node, unsigned int state)