linux-kernel - [PATCH V2] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug

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Date:   Wed, 26 Jul 2017 22:31:08 -0400
From:   Song liwei <liwei.song@...driver.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>
CC:     linux-acpi <linux-acpi@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        LiweiSong <liwei.song@...driver.com>
Subject: [PATCH V2] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug

From: Liwei Song <liwei.song@...driver.com>

This is a follow up to commit f712c71f7b2b ("ACPI, APEI: Fixup common
access width firmware bug") fix the following firmware bug:

[Firmware Bug]: APEI: Invalid bit width + offset in GAR [0xb2/16/0/1/1]

This is due to an 8-bit access width is specified for a 16-bit register,
Rearrange the condition and add 8-bit width check.

Signed-off-by: Liwei Song <liwei.song@...driver.com>
---
 drivers/acpi/apei/apei-base.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
index da370e1..eca3d7a 100644
--- a/drivers/acpi/apei/apei-base.c
+++ b/drivers/acpi/apei/apei-base.c
@@ -604,12 +604,12 @@ static int apei_check_gar(struct acpi_generic_address *reg, u64 *paddr,
 	*access_bit_width = 1UL << (access_size_code + 2);
 
 	/* Fixup common BIOS bug */
-	if (bit_width == 32 && bit_offset == 0 && (*paddr & 0x03) == 0 &&
-	    *access_bit_width < 32)
-		*access_bit_width = 32;
-	else if (bit_width == 64 && bit_offset == 0 && (*paddr & 0x07) == 0 &&
-	    *access_bit_width < 64)
-		*access_bit_width = 64;
+	if (*access_bit_width < bit_width && bit_offset == 0) {
+		if ((bit_width == 16 && (*paddr & 0x01) == 0) ||
+		    (bit_width == 32 && (*paddr & 0x03) == 0) ||
+		    (bit_width == 64 && (*paddr & 0x07) == 0))
+			*access_bit_width = bit_width;
+	}
 
 	if ((bit_width + bit_offset) > *access_bit_width) {
 		pr_warning(FW_BUG APEI_PFX
-- 
2.7.4