[PATCH] iommu/amd: Fix get_acpihid_device_id

Raul E Rangel rrangel at chromium.org
Fri May 8 22:48:30 UTC 2020

acpi_dev_hid_uid_match expects a null pointer for UID if it doesn't
exist. The acpihid_map_entry contains a char buffer for holding the
UID. If no UID was provided in the IVRS table, this buffer will be
zeroed. If we pass in a null string, acpi_dev_hid_uid_match will return
false because it will try and match an empty string to the ACPI UID of
the device.

Fixes: ae5e6c6439c3 ("iommu/amd: Switch to use acpi_dev_hid_uid_match()")
Signed-off-by: Raul E Rangel <rrangel at chromium.org>

 drivers/iommu/amd_iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 20cce366e951..06f603366cb1 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -125,7 +125,8 @@ static inline int get_acpihid_device_id(struct device *dev,
 		return -ENODEV;
 	list_for_each_entry(p, &acpihid_map, list) {
-		if (acpi_dev_hid_uid_match(adev, p->hid, p->uid)) {
+		if (acpi_dev_hid_uid_match(adev, p->hid,
+					   p->uid[0] ? p->uid : NULL)) {
 			if (entry)
 				*entry = p;
 			return p->devid;

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