v4.19.13 snapshot.
diff --git a/arch/x86/mm/amdtopology.c b/arch/x86/mm/amdtopology.c
new file mode 100644
index 0000000..048c761
--- /dev/null
+++ b/arch/x86/mm/amdtopology.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD NUMA support.
+ * Discover the memory map and associated nodes.
+ *
+ * This version reads it directly from the AMD northbridge.
+ *
+ * Copyright 2002,2003 Andi Kleen, SuSE Labs.
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/nodemask.h>
+#include <linux/memblock.h>
+#include <linux/bootmem.h>
+
+#include <asm/io.h>
+#include <linux/pci_ids.h>
+#include <linux/acpi.h>
+#include <asm/types.h>
+#include <asm/mmzone.h>
+#include <asm/proto.h>
+#include <asm/e820/api.h>
+#include <asm/pci-direct.h>
+#include <asm/numa.h>
+#include <asm/mpspec.h>
+#include <asm/apic.h>
+#include <asm/amd_nb.h>
+
+static unsigned char __initdata nodeids[8];
+
+static __init int find_northbridge(void)
+{
+	int num;
+
+	for (num = 0; num < 32; num++) {
+		u32 header;
+
+		header = read_pci_config(0, num, 0, 0x00);
+		if (header != (PCI_VENDOR_ID_AMD | (0x1100<<16)) &&
+			header != (PCI_VENDOR_ID_AMD | (0x1200<<16)) &&
+			header != (PCI_VENDOR_ID_AMD | (0x1300<<16)))
+			continue;
+
+		header = read_pci_config(0, num, 1, 0x00);
+		if (header != (PCI_VENDOR_ID_AMD | (0x1101<<16)) &&
+			header != (PCI_VENDOR_ID_AMD | (0x1201<<16)) &&
+			header != (PCI_VENDOR_ID_AMD | (0x1301<<16)))
+			continue;
+		return num;
+	}
+
+	return -ENOENT;
+}
+
+int __init amd_numa_init(void)
+{
+	u64 start = PFN_PHYS(0);
+	u64 end = PFN_PHYS(max_pfn);
+	unsigned numnodes;
+	u64 prevbase;
+	int i, j, nb;
+	u32 nodeid, reg;
+	unsigned int bits, cores, apicid_base;
+
+	if (!early_pci_allowed())
+		return -EINVAL;
+
+	nb = find_northbridge();
+	if (nb < 0)
+		return nb;
+
+	pr_info("Scanning NUMA topology in Northbridge %d\n", nb);
+
+	reg = read_pci_config(0, nb, 0, 0x60);
+	numnodes = ((reg >> 4) & 0xF) + 1;
+	if (numnodes <= 1)
+		return -ENOENT;
+
+	pr_info("Number of physical nodes %d\n", numnodes);
+
+	prevbase = 0;
+	for (i = 0; i < 8; i++) {
+		u64 base, limit;
+
+		base = read_pci_config(0, nb, 1, 0x40 + i*8);
+		limit = read_pci_config(0, nb, 1, 0x44 + i*8);
+
+		nodeids[i] = nodeid = limit & 7;
+		if ((base & 3) == 0) {
+			if (i < numnodes)
+				pr_info("Skipping disabled node %d\n", i);
+			continue;
+		}
+		if (nodeid >= numnodes) {
+			pr_info("Ignoring excess node %d (%Lx:%Lx)\n", nodeid,
+				base, limit);
+			continue;
+		}
+
+		if (!limit) {
+			pr_info("Skipping node entry %d (base %Lx)\n",
+				i, base);
+			continue;
+		}
+		if ((base >> 8) & 3 || (limit >> 8) & 3) {
+			pr_err("Node %d using interleaving mode %Lx/%Lx\n",
+			       nodeid, (base >> 8) & 3, (limit >> 8) & 3);
+			return -EINVAL;
+		}
+		if (node_isset(nodeid, numa_nodes_parsed)) {
+			pr_info("Node %d already present, skipping\n",
+				nodeid);
+			continue;
+		}
+
+		limit >>= 16;
+		limit++;
+		limit <<= 24;
+
+		if (limit > end)
+			limit = end;
+		if (limit <= base)
+			continue;
+
+		base >>= 16;
+		base <<= 24;
+
+		if (base < start)
+			base = start;
+		if (limit > end)
+			limit = end;
+		if (limit == base) {
+			pr_err("Empty node %d\n", nodeid);
+			continue;
+		}
+		if (limit < base) {
+			pr_err("Node %d bogus settings %Lx-%Lx.\n",
+			       nodeid, base, limit);
+			continue;
+		}
+
+		/* Could sort here, but pun for now. Should not happen anyroads. */
+		if (prevbase > base) {
+			pr_err("Node map not sorted %Lx,%Lx\n",
+			       prevbase, base);
+			return -EINVAL;
+		}
+
+		pr_info("Node %d MemBase %016Lx Limit %016Lx\n",
+			nodeid, base, limit);
+
+		prevbase = base;
+		numa_add_memblk(nodeid, base, limit);
+		node_set(nodeid, numa_nodes_parsed);
+	}
+
+	if (!nodes_weight(numa_nodes_parsed))
+		return -ENOENT;
+
+	/*
+	 * We seem to have valid NUMA configuration.  Map apicids to nodes
+	 * using the coreid bits from early_identify_cpu.
+	 */
+	bits = boot_cpu_data.x86_coreid_bits;
+	cores = 1 << bits;
+	apicid_base = 0;
+
+	/*
+	 * get boot-time SMP configuration:
+	 */
+	early_get_smp_config();
+
+	if (boot_cpu_physical_apicid > 0) {
+		pr_info("BSP APIC ID: %02x\n", boot_cpu_physical_apicid);
+		apicid_base = boot_cpu_physical_apicid;
+	}
+
+	for_each_node_mask(i, numa_nodes_parsed)
+		for (j = apicid_base; j < cores + apicid_base; j++)
+			set_apicid_to_node((i << bits) + j, i);
+
+	return 0;
+}