linux-kernel - [PATCH -v2] ACPI, APEI: Fix BERT resources conflict with ACPI NVS area

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Date:   Mon, 20 Feb 2017 09:12:58 +0800
From:   "Huang, Ying" <ying.huang@...el.com>
To:     "Rafael J . Wysocki" <rjw@...ysocki.net>
Cc:     Huang Ying <ying.huang@...el.com>, Len Brown <lenb@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        Tomasz Nowicki <tomasz.nowicki@...aro.org>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH -v2] ACPI, APEI: Fix BERT resources conflict with ACPI NVS area

From: Huang Ying <ying.huang@...el.com>

It was reported that on some machines, there is overlap between ACPI
NVS area and BERT address range.  This appears reasonable because BERT
contents need to be non-volatile across reboot.  But this will cause
resources conflict in current Linux kernel implementation because the
ACPI NVS area is marked as busy.  The resource conflict is fixed via
excluding the ACPI NVS area when requesting IO resources for BERT.
When accessing the BERT contents, the whole BERT address range will be
ioremapped and accessed.

Reported-and-tested-by: Hans Kristian Rosbach <hansr@...kesider.no>
Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
---
 drivers/acpi/apei/bert.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/apei/bert.c b/drivers/acpi/apei/bert.c
index a05b5c0cf181..12771fcf0417 100644
--- a/drivers/acpi/apei/bert.c
+++ b/drivers/acpi/apei/bert.c
@@ -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;
 }
-- 
2.11.0