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Re: [XEN RFC PATCH 22/40] xen/arm: introduce a helper to parse device tree processor node

Hi Wei,

On 11/08/2021 11:24, Wei Chen wrote:
Processor NUMA ID information is stored in device tree's processor
node as "numa-node-id". We need a new helper to parse this ID from
processor node. If we get this ID from processor node, this ID's
validity still need to be checked. Once we got a invalid NUMA ID
from any processor node, the device tree will be marked as NUMA
information invalid.

Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
  xen/arch/arm/numa_device_tree.c | 41 +++++++++++++++++++++++++++++++--
  1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/numa_device_tree.c b/xen/arch/arm/numa_device_tree.c
index 1c74ad135d..37cc56acf3 100644
--- a/xen/arch/arm/numa_device_tree.c
+++ b/xen/arch/arm/numa_device_tree.c
@@ -20,16 +20,53 @@
  #include <xen/init.h>
  #include <xen/nodemask.h>
  #include <xen/numa.h>
+#include <xen/device_tree.h>
+#include <asm/setup.h>
s8 device_tree_numa = 0;
+static nodemask_t processor_nodes_parsed __initdata;
-int srat_disabled(void)
+static int srat_disabled(void)
      return numa_off || device_tree_numa < 0;
-void __init bad_srat(void)
+static __init void bad_srat(void)
      printk(KERN_ERR "DT: NUMA information is not used.\n");
      device_tree_numa = -1;
+/* Callback for device tree processor affinity */
+static int __init dtb_numa_processor_affinity_init(nodeid_t node)
+    if ( srat_disabled() )
+        return -EINVAL;
+    else if ( node == NUMA_NO_NODE || node >= MAX_NUMNODES ) {
+               bad_srat();
+               return -EINVAL;

You seem to have a mix of soft and hard tab in this file. Is there a lot of the code that was directly copied from Linux? If not, then the file should be using Xen coding style.

+       }
+    node_set(node, processor_nodes_parsed);
+    device_tree_numa = 1;
+    printk(KERN_INFO "DT: NUMA node %u processor parsed\n", node);
+    return 0;
+/* Parse CPU NUMA node info */
+int __init device_tree_parse_numa_cpu_node(const void *fdt, int node)

AFAICT, you are going to turn this helper static in a follow-up patch. This is a bad practice. Instead, the function should be static from the beginning. If it is not possible, then you should re-order the code.

In this case, I think you can add the boilerplate to parse the NUMA information (patch #25) here and then extend it in each patch.

+    uint32_t nid;
+    nid = device_tree_get_u32(fdt, node, "numa-node-id", MAX_NUMNODES);
+    printk(XENLOG_WARNING "CPU on NUMA node:%u\n", nid);
+    if ( nid >= MAX_NUMNODES )
+    {
+        printk(XENLOG_WARNING "Node id %u exceeds maximum value\n", nid);
+        return -EINVAL;
+    }
+    return dtb_numa_processor_affinity_init(nid);


Julien Grall



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