x86, numa: Fake apicid and pxm mappings for NUMA emulation

This patch adds the equivalent of acpi_fake_nodes() for AMD Northbridge
platforms.  The goal is to fake the apicid-to-node mappings for NUMA
emulation so the physical topology of the machine is correctly maintained
within the kernel.

This change also fakes proximity domains for both ACPI and k8 code so the
physical distance between emulated nodes is maintained via
node_distance().  This exports the correct distances via
/sys/devices/system/node/.../distance based on the underlying topology.

A new helper function, fake_physnodes(), is introduced to correctly
invoke the correct NUMA code to fake these two mappings based on the
system type.  If there is no underlying NUMA configuration, all cpus are
mapped to node 0 for local distance.

Since acpi_fake_nodes() is no longer called with CONFIG_ACPI_NUMA, it's
prototype can be removed from the header file for such a configuration.

Signed-off-by: David Rientjes <rientjes@google.com>
LKML-Reference: <alpine.DEB.2.00.1012221701360.3701@chino.kir.corp.google.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

2 files changed, 1 insertions, 5 deletions

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index b326fa99db57..8288daf72dc9 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -193,11 +193,6 @@ extern int acpi_scan_nodes(unsigned long start, unsigned long end);
 extern void acpi_fake_nodes(const struct bootnode *fake_nodes,
                                    int num_nodes);
 #endif
-#else
-static inline void acpi_fake_nodes(const struct bootnode *fake_nodes,
-                                   int num_nodes)
-{
-}
 #endif /* CONFIG_ACPI_NUMA */
 
 #define acpi_unlazy_tlb(x)      leave_mm(x)
diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
index 9c16cde63f04..8f6192c1592c 100644
--- a/arch/x86/include/asm/amd_nb.h
+++ b/arch/x86/include/asm/amd_nb.h
@@ -13,6 +13,7 @@ extern int amd_numa_init(unsigned long start_pfn, unsigned long end_pfn);
 extern int amd_scan_nodes(void);
 
 #ifdef CONFIG_NUMA_EMU
+extern void amd_fake_nodes(const struct bootnode *nodes, int nr_nodes);
 extern int amd_get_nodes(struct bootnode *nodes);
 #endif