linux-kernel - Re: [PATCH v2 2/3] RAS/AMD/FMPM: Save SPA values

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Date: Fri, 1 Mar 2024 16:50:34 +0100
From: Borislav Petkov <bp@...en8.de>
To: Yazen Ghannam <yazen.ghannam@....com>
Cc: tony.luck@...el.com, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org, avadhut.naik@....com,
	john.allen@....com, muralidhara.mk@....com, sathyapriya.k@....com,
	naveenkrishna.chatradhi@....com
Subject: Re: [PATCH v2 2/3] RAS/AMD/FMPM: Save SPA values

On Fri, Mar 01, 2024 at 08:37:47AM -0600, Yazen Ghannam wrote:
> The system physical address (SPA) of an error is not a stable value. It
> will change depending on the location of the memory: parts can be
> swapped. And it will change depending on memory topology: NUMA nodes
> and/or interleaving can be adjusted.
> 
> Therefore, the SPA value is not part of the "FRU Memory Poison" record
> format. And it will not be saved to persistent storage.
> 
> However, the SPA values can be helpful during debug and for system
> admins during run time.
> 
> Save the SPA values in a separate structure. This is updated when
> records are restored and when new errors are saved.
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> ---
> Link:
> https://lore.kernel.org/r/20240226152941.2615007-3-yazen.ghannam@amd.com
> 
> v1->v2:
> * Changed variable names to remove "sys_" prefix. (Boris)
> * Used "spa_" prefix to highlight that these are for SPA values. (Yazen)
> * Added warning to "index out-of-bound" condition. (Boris)
> * Reworked save_spa() flow to get a valid array position before saving
>   SPA value (Yazen).
> 
>  drivers/ras/amd/fmpm.c | 68 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 68 insertions(+)

Fixups ontop:

---

diff --git a/drivers/ras/amd/fmpm.c b/drivers/ras/amd/fmpm.c
index a7bb36eb60cb..8c3188488673 100644
--- a/drivers/ras/amd/fmpm.c
+++ b/drivers/ras/amd/fmpm.c
@@ -125,7 +125,7 @@ static u64 *spa_entries;
 		  0x12, 0x0a, 0x44, 0x58)
 
 /**
- * DOC: fru_poison_entries (byte)
+ * DOC: max_nr_entries (byte)
  * Maximum number of descriptor entries possible for each FRU.
  *
  * Values between '1' and '255' are valid.
@@ -285,10 +285,12 @@ static void save_spa(struct fru_rec *rec, unsigned int entry,
 	unsigned long spa;
 
 	if (entry >= max_nr_entries) {
-		pr_warn_once("entry out-of-bounds\n");
+		pr_warn_once("FRU descriptor entry %d out-of-bounds (max: %d)\n",
+			     entry, max_nr_entries);
 		return;
 	}
 
+	/* spa_nr_entries is always multiple of max_nr_entries */
 	for (i = 0; i < spa_nr_entries; i += max_nr_entries) {
 		fru_idx = i / max_nr_entries;
 		if (fru_records[fru_idx] == rec)
@@ -296,7 +298,7 @@ static void save_spa(struct fru_rec *rec, unsigned int entry,
 	}
 
 	if (i >= spa_nr_entries) {
-		pr_warn_once("record not found");
+		pr_warn_once("FRU record %d not found\n", i);
 		return;
 	}
 
-- 
Regards/Gruss,
    Boris.

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