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From:   Yazen Ghannam <yazen.ghannam@amd.com>
To:     <bp@alien8.de>, <linux-edac@vger.kernel.org>
CC:     <linux-kernel@vger.kernel.org>, <muralidhara.mk@amd.com>,
        <naveenkrishna.chatradhi@amd.com>,
        Yazen Ghannam <yazen.ghannam@amd.com>
Subject: [PATCH v2 22/22] EDAC/amd64: Add get_err_info() to pvt->ops
Date:   Fri, 27 Jan 2023 17:04:19 +0000
Message-ID: <20230127170419.1824692-23-yazen.ghannam@amd.com>
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From: Muralidhara M K <muralidhara.mk@amd.com>

GPU Nodes will use a different method to determine the chip select
and channel of an error. A function pointer should be used rather
than introduce another branching condition.

Prepare for this by adding get_err_info() to pvt->ops. This function is
only called from the modern code path, so a legacy function is not
defined.

Make sure to call this after MCA_STATUS[SyndV] is checked, since the
csrow value is found in MCA_SYND.

Signed-off-by: Muralidhara M K <muralidhara.mk@amd.com>
Co-developed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
[Rebased/reworked patch and reworded commit message]
Co-developed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
Link:
https://lore.kernel.org/r/20220509145534.44912-19-yazen.ghannam@amd.com

v1->v2:
* Drop a redundant line in code comment.

 drivers/edac/amd64_edac.c | 13 ++++++++-----
 drivers/edac/amd64_edac.h |  1 +
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index 6b450544a892..ee291859cee3 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -2974,10 +2974,14 @@ static inline void decode_bus_error(int node_id, struct mce *m)
  * Currently, we can derive the channel number by looking at the 6th nibble in
  * the instance_id. For example, instance_id=0xYXXXXX where Y is the channel
  * number.
+ *
+ * For DRAM ECC errors, the Chip Select number is given in bits [2:0] of
+ * the MCA_SYND[ErrorInformation] field.
  */
-static int find_umc_channel(struct mce *m)
+static void umc_get_err_info(struct mce *m, struct err_info *err)
 {
-	return (m->ipid & GENMASK(31, 0)) >> 20;
+	err->channel = (m->ipid & GENMASK(31, 0)) >> 20;
+	err->csrow = m->synd & 0x7;
 }
 
 static void decode_umc_error(int node_id, struct mce *m)
@@ -2999,8 +3003,6 @@ static void decode_umc_error(int node_id, struct mce *m)
 	if (m->status & MCI_STATUS_DEFERRED)
 		ecc_type = 3;
 
-	err.channel = find_umc_channel(m);
-
 	if (!(m->status & MCI_STATUS_SYNDV)) {
 		err.err_code = ERR_SYND;
 		goto log_error;
@@ -3015,7 +3017,7 @@ static void decode_umc_error(int node_id, struct mce *m)
 			err.err_code = ERR_CHANNEL;
 	}
 
-	err.csrow = m->synd & 0x7;
+	pvt->ops->get_err_info(m, &err);
 
 	if (umc_normaddr_to_sysaddr(m->addr, pvt->mc_node_id, err.channel, &sys_addr)) {
 		err.err_code = ERR_NORM_ADDR;
@@ -3685,6 +3687,7 @@ static struct low_ops umc_ops = {
 	.ecc_enabled			= umc_ecc_enabled,
 	.setup_mci_misc_attrs		= umc_setup_mci_misc_attrs,
 	.dump_misc_regs			= umc_dump_misc_regs,
+	.get_err_info			= umc_get_err_info,
 };
 
 /* Use Family 16h versions for defaults and adjust as needed below. */
diff --git a/drivers/edac/amd64_edac.h b/drivers/edac/amd64_edac.h
index 1c64fd4a14b1..e84fe0d4120a 100644
--- a/drivers/edac/amd64_edac.h
+++ b/drivers/edac/amd64_edac.h
@@ -470,6 +470,7 @@ struct low_ops {
 	bool (*ecc_enabled)(struct amd64_pvt *pvt);
 	void (*setup_mci_misc_attrs)(struct mem_ctl_info *mci);
 	void (*dump_misc_regs)(struct amd64_pvt *pvt);
+	void (*get_err_info)(struct mce *m, struct err_info *err);
 };
 
 int __amd64_read_pci_cfg_dword(struct pci_dev *pdev, int offset,
-- 
2.25.1