Currently for DeviceTree bootup, x86 code does the default mapping of
CPUs to NUMA, which is wrong. This can cause incorrect mapping and WARN
on a SMT enabled systems like below:

CPU #1's smt-sibling CPU #0 is not on the same node! [node: 1 != 0]. Ignoring dependency.
WARNING: CPU: 1 PID: 0 at topology_sane.isra.0+0x5c/0x6d
match_smt+0xf6/0xfc
set_cpu_sibling_map.cold+0x24f/0x512
start_secondary+0x5c/0x110

Add the set_apicid_to_node() function in dtb_cpu_setup() for allowing
the NUMA to CPU mapping for DeviceTree platforms.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
---
 arch/x86/kernel/devicetree.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 0d3a50e8395d..b93ce8a39ff7 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -24,6 +24,7 @@
 #include <asm/pci_x86.h>
 #include <asm/setup.h>
 #include <asm/i8259.h>
+#include <asm/numa.h>
 #include <asm/prom.h>
 
 __initdata u64 initial_dtb;
@@ -137,6 +138,7 @@ static void __init dtb_cpu_setup(void)
 			continue;
 		}
 		topology_register_apic(apic_id, CPU_ACPIID_INVALID, true);
+		set_apicid_to_node(apic_id, of_node_to_nid(dn));
 	}
 }
 
-- 
2.34.1

The following commit has been merged into the x86/platform branch of tip:

Commit-ID:     85900d061884de85f557a06cf56ff69dfae07e26
Gitweb:        https://git.kernel.org/tip/85900d061884de85f557a06cf56ff69dfae07e26
Author:        Saurabh Sengar <ssengar@linux.microsoft.com>
AuthorDate:    Tue, 02 Apr 2024 07:40:29 -07:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 03 Apr 2024 08:49:15 +02:00

x86/of: Map NUMA node to CPUs as per DeviceTree

Currently for DeviceTree bootup, x86 code does the default mapping of
CPUs to NUMA, which is wrong. This can cause incorrect mapping and WARNs
on SMT enabled systems:

  CPU #1's smt-sibling CPU #0 is not on the same node! [node: 1 != 0]. Ignoring dependency.
  WARNING: CPU: 1 PID: 0 at topology_sane.isra.0+0x5c/0x6d
  match_smt+0xf6/0xfc
  set_cpu_sibling_map.cold+0x24f/0x512
  start_secondary+0x5c/0x110

Call the set_apicid_to_node() function in dtb_cpu_setup() for setting
the NUMA to CPU mapping for DeviceTree platforms.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/1712068830-4513-4-git-send-email-ssengar@linux.microsoft.com
---
 arch/x86/kernel/devicetree.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 0d3a50e..b93ce8a 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -24,6 +24,7 @@
 #include <asm/pci_x86.h>
 #include <asm/setup.h>
 #include <asm/i8259.h>
+#include <asm/numa.h>
 #include <asm/prom.h>
 
 __initdata u64 initial_dtb;
@@ -137,6 +138,7 @@ static void __init dtb_cpu_setup(void)
 			continue;
 		}
 		topology_register_apic(apic_id, CPU_ACPIID_INVALID, true);
+		set_apicid_to_node(apic_id, of_node_to_nid(dn));
 	}
 }