On 08/20/2020 12:48 AM, Atish Patra wrote:

On Tue, Aug 18, 2020 at 8:19 PM Anshuman Khandual
[off-list ref] wrote:

quoted

On 08/15/2020 03:17 AM, Atish Patra wrote:

quoted

ARM64 numa implementation is generic enough that RISC-V can reuse that
implementation with very minor cosmetic changes. This will help both
ARM64 and RISC-V in terms of maintanace and feature improvement

Move the numa implementation code to common directory so that both ISAs
can reuse this. This doesn't introduce any function changes for ARM64.

Signed-off-by: Atish Patra <redacted>
---
 arch/arm64/Kconfig                            |  1 +
 arch/arm64/include/asm/numa.h                 | 45 +---------------
 arch/arm64/mm/Makefile                        |  1 -
 drivers/base/Kconfig                          |  6 +++
 drivers/base/Makefile                         |  1 +
 .../mm/numa.c => drivers/base/arch_numa.c     |  0
 include/asm-generic/numa.h                    | 51 +++++++++++++++++++
 7 files changed, 60 insertions(+), 45 deletions(-)
 rename arch/arm64/mm/numa.c => drivers/base/arch_numa.c (100%)
 create mode 100644 include/asm-generic/numa.h

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d232837cbee..955a0cf75b16 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -960,6 +960,7 @@ config HOTPLUG_CPU
 # Common NUMA Features
 config NUMA
      bool "NUMA Memory Allocation and Scheduler Support"
+     select GENERIC_ARCH_NUMA

So this introduces a generic NUMA framework selectable with GENERIC_ARCH_NUMA.

quoted

      select ACPI_NUMA if ACPI
      select OF_NUMA
      help

diff --git a/arch/arm64/include/asm/numa.h b/arch/arm64/include/asm/numa.h
index 626ad01e83bf..8c8cf4297cc3 100644
--- a/arch/arm64/include/asm/numa.h
+++ b/arch/arm64/include/asm/numa.h

@@ -3,49 +3,6 @@
 #define __ASM_NUMA_H

 #include <asm/topology.h>
-
-#ifdef CONFIG_NUMA
-
-#define NR_NODE_MEMBLKS              (MAX_NUMNODES * 2)
-
-int __node_distance(int from, int to);
-#define node_distance(a, b) __node_distance(a, b)
-
-extern nodemask_t numa_nodes_parsed __initdata;
-
-extern bool numa_off;
-
-/* Mappings between node number and cpus on that node. */
-extern cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
-void numa_clear_node(unsigned int cpu);
-
-#ifdef CONFIG_DEBUG_PER_CPU_MAPS
-const struct cpumask *cpumask_of_node(int node);
-#else
-/* Returns a pointer to the cpumask of CPUs on Node 'node'. */
-static inline const struct cpumask *cpumask_of_node(int node)
-{
-     return node_to_cpumask_map[node];
-}
-#endif
-
-void __init arm64_numa_init(void);
-int __init numa_add_memblk(int nodeid, u64 start, u64 end);
-void __init numa_set_distance(int from, int to, int distance);
-void __init numa_free_distance(void);
-void __init early_map_cpu_to_node(unsigned int cpu, int nid);
-void numa_store_cpu_info(unsigned int cpu);
-void numa_add_cpu(unsigned int cpu);
-void numa_remove_cpu(unsigned int cpu);
-
-#else        /* CONFIG_NUMA */
-
-static inline void numa_store_cpu_info(unsigned int cpu) { }
-static inline void numa_add_cpu(unsigned int cpu) { }
-static inline void numa_remove_cpu(unsigned int cpu) { }
-static inline void arm64_numa_init(void) { }
-static inline void early_map_cpu_to_node(unsigned int cpu, int nid) { }
-
-#endif       /* CONFIG_NUMA */
+#include <asm-generic/numa.h>

 #endif       /* __ASM_NUMA_H */

diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index d91030f0ffee..928c308b044b 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile

@@ -6,7 +6,6 @@ obj-y                         := dma-mapping.o extable.o fault.o init.o \
 obj-$(CONFIG_HUGETLB_PAGE)   += hugetlbpage.o
 obj-$(CONFIG_PTDUMP_CORE)    += dump.o
 obj-$(CONFIG_PTDUMP_DEBUGFS) += ptdump_debugfs.o
-obj-$(CONFIG_NUMA)           += numa.o
 obj-$(CONFIG_DEBUG_VIRTUAL)  += physaddr.o
 KASAN_SANITIZE_physaddr.o    += n

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 8d7001712062..73c2151de194 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig

@@ -210,4 +210,10 @@ config GENERIC_ARCH_TOPOLOGY
        appropriate scaling, sysfs interface for reading capacity values at
        runtime.

+config GENERIC_ARCH_NUMA
+     bool
+     help
+       Enable support for generic numa implementation. Currently, RISC-V
+       and ARM64 uses it.
+
 endmenu

diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 157452080f3d..c3d02c644222 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile

@@ -23,6 +23,7 @@ obj-$(CONFIG_PINCTRL) += pinctrl.o
 obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
 obj-$(CONFIG_GENERIC_MSI_IRQ_DOMAIN) += platform-msi.o
 obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY) += arch_topology.o
+obj-$(CONFIG_GENERIC_ARCH_NUMA) += arch_numa.o

 obj-y                        += test/

diff --git a/arch/arm64/mm/numa.c b/drivers/base/arch_numa.c
similarity index 100%
rename from arch/arm64/mm/numa.c
rename to drivers/base/arch_numa.c

drivers/base/ does not seem right place to host generic NUMA code.

I chose drivers/base because the common topology code is also present there.
drivers/base/arch_topology.c under GENERIC_ARCH_TOPOLOGY
The idea is to keep all common arch(at least between RISC-V & ARM64)
related code at one place.

quoted

Probably it should be either mm/ or kernel/. The other question here

I am fine with mm/arch_numa.c as well if that is preferred over driver/base.

GENERIC_ARCH_NUMA being near other shared code such as GENERIC_ARCH_TOPOLOGY
do make sense. That being said, its a small nit and can be figured out later.

quoted

would be if existing arm64 NUMA implementation is sufficient enough
for generic NUMA. I would expect any platform selecting this config
should get some NUMA enabled, will be that be true with present code ?

It is for RISC-V. Here is the RISC-V support patch (last patch in the series)

http://lists.infradead.org/pipermail/linux-riscv/2020-August/001659.html

+ Jonathan Cameron [off-list ref]

There is another patch/discussion which is trying to unify ARM64 NUMA init
code with X86 (https://patchwork.kernel.org/patch/11651437/). I am wondering
if all three platforms could use GENERIC_ARCH_NUMA.
 

quoted

Otherwise it will be difficult to name it as GENERIC_ARCH_NUMA.

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