Linux Kernel PHY State Management Vulnerability in AMD Display Driver on DCN35

A vulnerability exists in the Linux kernel's AMD display driver for the DCN35 architecture. The issue arises from improper management of the PHY state when disabling TMDS output, leading to a condition where the OTG remains stuck. This can disrupt the DCHVM's ability to acknowledge invalidations, causing synchronization issues. The vulnerability has been addressed by backporting a fix from the DCN401 implementation, ensuring that the transition to enabling the PHY PLL is handled atomically to prevent timing out issues with the IOMMU watchdog.

Impact

The vulnerability can cause a hang in the DCHVM's ability to acknowledge invalidations, disrupting synchronization processes and potentially leading to broader system performance issues.

Remediation

Users can apply the patch available in the Linux kernel stable tree to address this vulnerability. The patch can be downloaded as part of the Linux kernel snapshot corresponding to the commit ID 'd1f7ceb00e8956ff6d183b7b45ef4e73c96f4c51'.