AMD Zen CPUs Get Linux Kernel Workaround for TLBI Erratum 1718 Stale Translation Entries Issue

The Linux 7.3-rc7 kernel release incorporates a software workaround for AMD TLBI Erratum 1718. This update provides a mitigation path for systems running affected Zen processors that have not yet received the necessary CPU microcode update.

What happened

AMD TLBI Erratum 1718 involves a defect in certain Zen processors regarding the Translation Lookaside Buffer Invalidate Instruction. According to Phoronix, this defect can lead to stale translation entries remaining in the buffer. The primary mitigation strategy has historically been a CPU microcode update provided by the hardware vendor. However, not all systems may have access to or have applied this specific microcode update.

To address this gap, the Linux kernel development team has introduced a workaround in the 7.3-rc7 release. This kernel-level fix allows operating systems to manage the erratum without relying solely on the hardware microcode. Phoronix reports that this workaround is designed specifically for those on affected AMD CPUs who are not running the updated microcode. The change ensures that the kernel can handle the translation entry issues safely.

Why it matters

Organisations relying on AMD Zen processors must ensure their systems are protected against this erratum. The presence of stale translation entries can potentially impact system stability and security. For IT managers, this kernel update offers a critical alternative if microcode updates are unavailable or delayed.

The Linux 7.3-rc7 inclusion demonstrates the importance of kernel-level mitigations in hardware security chains. Back-porting this fix to prior kernel versions will extend protection to older Linux distributions. This reduces the window of exposure for enterprise environments that cannot immediately upgrade to the latest kernel. It ensures a broader range of systems can mitigate the risk associated with Erratum 1718.

Next steps

• Review current Linux kernel versions on all AMD Zen systems.
• Verify whether the specific CPU microcode update for Erratum 1718 is installed.
• Plan to upgrade to Linux 7.3-rc7 or later stable releases containing the back-port.
• Monitor vendor advisories for further developments regarding this erratum.

What to do and how to stay safe: Linux

• Audit server inventories to identify systems running affected AMD Zen processors.
• Check current kernel versions to determine if they include the 1718 workaround.
• Verify if the latest CPU microcode is applied as the primary mitigation.
• Once the vendor provides an update for older kernels, schedule the patch deployment.

Step-by-step guide: Wifi router security: Stop hidden admin access from leaking data

General security guidance from the Packet Tribune newsroom. It is not confirmed advice from the organisations named in this story.

Frequently asked questions

Which Linux version includes the workaround for AMD TLBI Erratum 1718?

The Linux 7.3-rc7 kernel includes the initial workaround, with plans to back-port it.

What is the primary cause of AMD TLBI Erratum 1718?

It is a defect where the Translation Lookaside Buffer Invalidate Instruction leads to stale entries.

Is this fix available for older Linux kernel versions?

Yes, the workaround is scheduled to be back-ported to prior kernel versions.