[PATCH] hw/arm/virt: Prevent CPUs in one socket to span mutiple NUMA nodes

[Gavin Shan]

Linux kernel guest reports warning when two CPUs in one socket have
been associated with different NUMA nodes, using the following command
lines.

  -smp 6,maxcpus=6,sockets=2,clusters=1,cores=3,threads=1 \
  -numa node,nodeid=0,cpus=0-1,memdev=ram0                \
  -numa node,nodeid=1,cpus=2-3,memdev=ram1                \
  -numa node,nodeid=2,cpus=4-5,memdev=ram2                \

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 1 at kernel/sched/topology.c:2271 
build_sched_domains+0x284/0x910
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0-268.el9.aarch64 #1
  pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc : build_sched_domains+0x284/0x910
  lr : build_sched_domains+0x184/0x910
  sp : ffff80000804bd50
  x29: ffff80000804bd50 x28: 0000000000000002 x27: 0000000000000000
  x26: ffff800009cf9a80 x25: 0000000000000000 x24: ffff800009cbf840
  x23: ffff000080325000 x22: ffff0000005df800 x21: ffff80000a4ce508
  x20: 0000000000000000 x19: ffff000080324440 x18: 0000000000000014
  x17: 00000000388925c0 x16: 000000005386a066 x15: 000000009c10cc2e
  x14: 00000000000001c0 x13: 0000000000000001 x12: ffff00007fffb1a0
  x11: ffff00007fffb180 x10: ffff80000a4ce508 x9 : 0000000000000041
  x8 : ffff80000a4ce500 x7 : ffff80000a4cf920 x6 : 0000000000000001
  x5 : 0000000000000001 x4 : 0000000000000007 x3 : 0000000000000002
  x2 : 0000000000001000 x1 : ffff80000a4cf928 x0 : 0000000000000001
  Call trace:
   build_sched_domains+0x284/0x910
   sched_init_domains+0xac/0xe0
   sched_init_smp+0x48/0xc8
   kernel_init_freeable+0x140/0x1ac
   kernel_init+0x28/0x140
   ret_from_fork+0x10/0x20

Fix it by preventing mutiple CPUs in one socket to be associated with
different NUMA nodes.

Reported-by: Yihuang Yu <yihyu@redhat.com>
Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 hw/arm/virt.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index ac626b3bef..e0af267c77 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -230,6 +230,39 @@ static bool cpu_type_valid(const char *cpu)
     return false;
 }
 
+static bool numa_state_valid(MachineState *ms)
+{
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
+    NumaState *state = ms->numa_state;
+    const CPUArchIdList *possible_cpus = mc->possible_cpu_arch_ids(ms);
+    const CPUArchId *cpus = possible_cpus->cpus;
+    int len = possible_cpus->len, i, j;
+
+    if (!state || state->num_nodes <= 1 || len <= 1) {
+        return true;
+    }
+
+    for (i = 0; i < len; i++) {
+        for (j = i + 1; j < len; j++) {
+            if (cpus[i].props.has_socket_id &&
+                cpus[i].props.has_node_id &&
+                cpus[j].props.has_socket_id &&
+                cpus[j].props.has_node_id &&
+                cpus[i].props.socket_id == cpus[j].props.socket_id &&
+                cpus[i].props.node_id != cpus[j].props.node_id) {
+                error_report("CPU-%d and CPU-%d in socket-%ld have been "
+                             "associated with node-%ld and node-%ld",
+                             i, j, cpus[i].props.socket_id,
+                             cpus[i].props.node_id,
+                             cpus[j].props.node_id);
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
 static void create_randomness(MachineState *ms, const char *node)
 {
     struct {
@@ -2040,6 +2073,10 @@ static void machvirt_init(MachineState *machine)
         exit(1);
     }
 
+    if (!numa_state_valid(machine)) {
+        exit(1);
+    }
+
     possible_cpus = mc->possible_cpu_arch_ids(machine);
 
     /*
-- 
2.23.0