ACPI, APEI: Fix BERT resources conflict with ACPI NVS area

From: Huang Ying <[email protected]>

It was reported that some firmware will use ACPI NVS area for BERT address range. This will cause resources conflict because the ACPI NVS area is marked as busy already. Fix this via excluding ACPI NVS area when requesting IO resources for BERT.

Reported-and-tested-by Hans Kristian Rosbach <[email protected]>

Signed-off-by "Huang, Ying" <[email protected]>

From: Huang Ying <[email protected]>

It was reported that some firmware will use ACPI NVS area for BERT address range. This will cause resources conflict because the ACPI NVS area is marked as busy already. Fix this via excluding ACPI NVS area when requesting IO resources for BERT.

Reported-and-tested-by Hans Kristian Rosbach <[email protected]>

Signed-off-by "Huang, Ying" <[email protected]>

---
 drivers/acpi/apei/bert.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

drivers/acpi/apei/bert.c +12 -8

index a05b5c0cf181..12771fcf0417 100644
@@ -97,6 +97,7 @@ static int __init bert_check_table(struct acpi_table_bert *bert_tab)
 
 static int __init bert_init(void)
 {
+	struct apei_resources bert_resources;
 	struct acpi_bert_region *boot_error_region;
 	struct acpi_table_bert *bert_tab;
 	unsigned int region_len;

@@ -127,13 +128,14 @@ static int __init bert_init(void)
 	}
 
 	region_len = bert_tab->region_length;
-	if (!request_mem_region(bert_tab->address, region_len, "APEI BERT")) {
-		pr_err("Can't request iomem region <%016llx-%016llx>.\n",
-		       (unsigned long long)bert_tab->address,
-		       (unsigned long long)bert_tab->address + region_len - 1);
-		return -EIO;
-	}
-
+	apei_resources_init(&bert_resources);
+	rc = apei_resources_add(&bert_resources, bert_tab->address,
+				region_len, true);
+	if (rc)
+		return rc;
+	rc = apei_resources_request(&bert_resources, "APEI BERT");
+	if (rc)
+		goto out_fini;
 	boot_error_region = ioremap_cache(bert_tab->address, region_len);
 	if (boot_error_region) {
 		bert_print_all(boot_error_region, region_len);

@@ -142,7 +144,9 @@ static int __init bert_init(void)
 		rc = -ENOMEM;
 	}
 
-	release_mem_region(bert_tab->address, region_len);
+	apei_resources_release(&bert_resources);
+out_fini:
+	apei_resources_fini(&bert_resources);
 
 	return rc;
 }

Quoted 7 lines · Ying

From: Huang Ying <[email protected]>

It was reported that some firmware will use ACPI NVS area for BERT address range. This will cause resources conflict because the ACPI NVS area is marked as busy already. Fix this via excluding ACPI NVS area when requesting IO resources for BERT.

Quoted 2 lines

Reported-and-tested-by Hans Kristian Rosbach <[email protected]>

Signed-off-by "Huang, Ying" <[email protected]>

Boris, what do you think?

Quoted 8 lines · Rafael J. Wysocki

Quoted 7 lines · Ying

From: Huang Ying <[email protected]>

It was reported that some firmware will use ACPI NVS area for BERT address range. This will cause resources conflict because the ACPI NVS area is marked as busy already. Fix this via excluding ACPI NVS area when requesting IO resources for BERT.

Quoted 4 lines

Quoted 2 lines

Reported-and-tested-by Hans Kristian Rosbach <[email protected]>

Signed-off-by "Huang, Ying" <[email protected]>

Boris, what do you think?

Lemme see, so the BERT is for hw errors which have happened during the previous boot and the machine couldn't handle them. So they do get saved in some mem in the fw for inspection during the next boot.

And "some firmware" has decided to write them into non-volatile storage
- because you should never ever forget those errors! :-)

And I don't understand the "fix" here: we're excluding the NVS area when mapping the BERT table but then how are we supposed to read those errors from there?

Or am I missing something obvious?

The NVS area is excluded when request the resources, because the NVS area has been marked as busy already. But the whole BERT memory area is mapped, so we can read from it.

Quoted 3 lines · Ying

The NVS area is excluded when request the resources, because the NVS area has been marked as busy already. But the whole BERT memory area is mapped, so we can read from it.

So you're saying the NVS area is part of the BERT area and we can access the whole range?

I am not sure whether the NVS area is a part of the BERT area, but apparently they are overlapped in some way. We will access the whole BERT area here via ioremap the whole range.

Quoted 3 lines · Ying

I am not sure whether the NVS area is a part of the BERT area, but apparently they are overlapped in some way. We will access the whole BERT area here via ioremap the whole range.

This is the part that was missing from the commit message - explaining *why* we need this fix.