CVE-2026-64172

Summary

In the Linux kernel, the following vulnerability has been resolved:

KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)

Hygon Family 18h CPUs are derived from AMD Family 17h (Zen1) silicon and share the same erratum #1235: hardware may read a stale IsRunning=1 bit during ICR write emulation and silently fail to generate an AVIC_IPI_FAILURE_TARGET_NOT_RUNNING VM-Exit on the sending vCPU.

The absence of the VM-Exit causes KVM to miss the required wakeup of blocking target vCPUs, leading to hung vCPUs and unbounded delays in guest execution.

Extend the existing AMD Family 17h erratum #1235 workaround to also cover Hygon Family 18h. With IPI virtualization disabled, KVM never sets IsRunning=1 in the Physical ID table, so every non-self IPI generates a VM-Exit and is correctly emulated.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux8de4a1c8164e5b2e40d1df764840a31de983f40b < 94ade38f317ea086a181db0e6b69c574b3b70a5eaffected
LinuxLinux8de4a1c8164e5b2e40d1df764840a31de983f40b < 9560e6fee887a9594a89fa265b5b9c79b1591803affected
LinuxLinux8de4a1c8164e5b2e40d1df764840a31de983f40b < 9a12fa5213cfc391e0eed63902d3be98f0913765affected
LinuxLinux6.17affected
LinuxLinux0 < 6.17unaffected
LinuxLinux6.18.34 <= 6.18.*unaffected
LinuxLinux7.0.11 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References