[PATCH] iommu/amd: Fix get_acpihid_device_id

From: Raul E Rangel
Date: Fri May 08 2020 - 18:48:38 EST


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@xxxxxxxxxxxx>
---

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;
--
2.26.2.645.ge9eca65c58-goog