linux-kernel - [PATCH] x86/numa: Map NUMA node to CPUs as per DeviceTree

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Message-Id: <1710265404-23146-1-git-send-email-ssengar@linux.microsoft.com>
Date: Tue, 12 Mar 2024 10:43:24 -0700
From: Saurabh Sengar <ssengar@...ux.microsoft.com>
To: dave.hansen@...ux.intel.com,
	luto@...nel.org,
	peterz@...radead.org,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	x86@...nel.org,
	hpa@...or.com,
	linux-kernel@...r.kernel.org
Cc: ssengar@...rosoft.com,
	sgeorgejohn@...rosoft.com
Subject: [PATCH] x86/numa: 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 WARN
on a SMT enabled system like below:

[0.417551] ------------[ cut here ]------------
[0.417551] Saurabh sched: CPU #1's smt-sibling CPU #0 is not on the same node! [node: 1 != 0]. Ignoring dependency.
[0.417551] WARNING: CPU: 1 PID: 0 at topology_sane.isra.0+0x5c/0x6d
[0.417551] Modules linked in:
[0.417551] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.1.71-microsoft-hcl+ #4
[0.417551] RIP: 0010:topology_sane.isra.0+0x5c/0x6d
[0.417551] Code: 41 39 dc 74 27 80 3d 32 ae 2d 00 00 75 1e 41 89 d9 45 89 e0 44 89 d6 48 c7 c7 00 a6 4a 88 c6 05 19 ae 2d 00 01 e8 6e 1f cb ff <0f> 0b 41 39 dc 5b 41 5c 0f 94 c0 5d c3 cc cc cc cc 55 48 8b 05 05
[0.417551] RSP: 0000:ffffc9000013feb0 EFLAGS: 00010086
[0.417551] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[0.417551] RDX: 0000000000000003 RSI: 0000000000000086 RDI: 00000000ffffffff
[0.417551] RBP: ffffc9000013fec0 R08: ffffffff88778160 R09: ffffffff88778160
[0.417551] R10: ffff888227fe26da R11: ffff888227fe26c1 R12: 0000000000000001
[0.417551] R13: 0000000000000000 R14: ffff888216415040 R15: 0000000000000000
[0.417551] FS:  0000000000000000(0000) GS:ffff888216400000(0000) knlGS:0000000000000000
[0.417551] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[0.417551] CR2: 0000000000000000 CR3: 0000000208809001 CR4: 0000000000330ea0
[0.417551] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[0.417551] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[0.417551] Call Trace:
[0.417551]  <TASK>
[0.417551]  ? show_regs.cold+0x1a/0x1f
[0.417551]  ? __warn+0x6e/0xc0
[0.417551]  ? report_bug+0x101/0x1a0
[0.417551]  ? handle_bug+0x40/0x70
[0.417551]  ? exc_invalid_op+0x19/0x70
[0.417551]  ? asm_exc_invalid_op+0x1b/0x20
[0.417551]  ? topology_sane.isra.0+0x5c/0x6d
[0.417551]  match_smt+0xf6/0xfc
[0.417551]  set_cpu_sibling_map.cold+0x24f/0x512
[0.417551]  start_secondary+0x5c/0x110
[0.417551]  secondary_startup_64_no_verify+0xcd/0xdb
[0.417551]  </TASK>
[0.417551] ---[ end trace 0000000000000000 ]---

Add the correct mapping of CPUs to NUMA node as per DeviceTree to fix
this issue.

Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
---
 arch/x86/mm/numa.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 65e9a6e..9dacf60 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -601,6 +601,23 @@ static void __init numa_init_array(void)
 	}
 }
 
+static void __init of_parse_and_init_cpus(void)
+{
+	struct device_node *dn;
+	int cpuid = 0;
+	int nid;
+
+	for_each_of_cpu_node(dn) {
+		if (cpuid >= NR_CPUS) {
+			pr_warn("NR_CPUS too small for %d cpuid\n", cpuid);
+			return;
+		}
+		nid = of_node_to_nid(dn);
+		numa_set_node(cpuid, nid);
+		cpuid++;
+	}
+}
+
 static int __init numa_init(int (*init_func)(void))
 {
 	int i;
@@ -645,6 +662,9 @@ static int __init numa_init(int (*init_func)(void))
 	if (ret < 0)
 		return ret;
 
+	if (acpi_disabled)
+		of_parse_and_init_cpus();
+
 	for (i = 0; i < nr_cpu_ids; i++) {
 		int nid = early_cpu_to_node(i);
 
-- 
1.8.3.1