[PATCH v4 2/4] EDAC/mce_amd: Extract node id from MCA_IPID

[Naveen Krishna Chatradhi <nchatrad@amd.com>]

On SMCA banks of the GPU nodes, the node id information is
available in register MCA_IPID[47:44](InstanceIdHi).

Convert the hardware node ID to a value used by Linux
where GPU nodes are sequencially after the CPU nodes.

Co-developed-by: Muralidhara M K <muralimk@amd.com>
Signed-off-by: Muralidhara M K <muralimk@amd.com>
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
Link: https://lkml.kernel.org/r/20210823185437.94417-3-nchatrad@amd.com
---
Changes since v3:
1. Use APIs from amd_nb to identify the gpu_node_start_id and cpu_node_count.
   Which is required to map the hardware node id to node id enumerated by Linux.

Changes since v2:
1. Modified subject and commit message
2. Added Reviewed by Yazen Ghannam

Changes since v1:
1. Modified the commit message
2. rearranged the conditions before calling decode_dram_ecc()

 drivers/edac/mce_amd.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/mce_amd.c b/drivers/edac/mce_amd.c
index 67dbf4c31271..af6caa76adc7 100644
--- a/drivers/edac/mce_amd.c
+++ b/drivers/edac/mce_amd.c
@@ -2,6 +2,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 
+#include <asm/amd_nb.h>
 #include <asm/cpu.h>
 
 #include "mce_amd.h"
@@ -1072,8 +1073,27 @@ static void decode_smca_error(struct mce *m)
 	if (xec < smca_mce_descs[bank_type].num_descs)
 		pr_cont(", %s.\n", smca_mce_descs[bank_type].descs[xec]);
 
-	if (bank_type == SMCA_UMC && xec == 0 && decode_dram_ecc)
-		decode_dram_ecc(topology_die_id(m->extcpu), m);
+	if (xec == 0 && decode_dram_ecc) {
+		int node_id = 0;
+
+		if (bank_type == SMCA_UMC) {
+			node_id = topology_die_id(m->extcpu);
+		} else if (bank_type == SMCA_UMC_V2) {
+			/*
+			 * SMCA_UMC_V2 exists on GPU nodes, extract the node id
+			 * from register MCA_IPID[47:44](InstanceIdHi).
+			 * The InstanceIdHi field represents the instance ID of the GPU.
+			 * Which needs to be mapped to a value used by Linux,
+			 * where GPU nodes are simply numerically after the CPU nodes.
+			 */
+			node_id = ((m->ipid >> 44) & 0xF) -
+				   amd_gpu_node_start_id() + amd_cpu_node_count();
+		} else {
+			return;
+		}
+
+		decode_dram_ecc(node_id, m);
+	}
 }
 
 static inline void amd_decode_err_code(u16 ec)
-- 
2.25.1