[PATCH 1/2] iommu/amd: Fix ivrs_acpihid cmdline parsing code

[Kim Phillips <kim.phillips@amd.com>]

The second (UID) strcmp in acpi_dev_hid_uid_match considers
"0" and "00" different, which can prevent device registration.

Have the AMD IOMMU driver's ivrs_acpihid parsing code remove
any leading zeroes to make the UID strcmp succeed.  Now users
can safely specify "AMDxxxxx:00" or "AMDxxxxx:0" and expect
the same behaviour.

Fixes: ca3bf5d47cec ("iommu/amd: Introduces ivrs_acpihid kernel parameter")
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Cc: stable@vger.kernel.org
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Cc: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd/init.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index fdc642362c14..ef0e1a4b5a11 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3471,6 +3471,13 @@ static int __init parse_ivrs_acpihid(char *str)
 		return 1;
 	}
 
+	/*
+	 * Ignore leading zeroes after ':', so e.g., AMDI0095:00
+	 * will match AMDI0095:0 in the second strcmp in acpi_dev_hid_uid_match
+	 */
+	while (*uid == '0' && *(uid + 1))
+		uid++;
+
 	i = early_acpihid_map_size++;
 	memcpy(early_acpihid_map[i].hid, hid, strlen(hid));
 	memcpy(early_acpihid_map[i].uid, uid, strlen(uid));
-- 
2.34.1