KVM: Disable AVIC IPI Virtualization on Hygon CPUs to Fix VCPU Hang
CVE-2026-64172 Published on July 19, 2026
KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)
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.
Products Associated with CVE-2026-64172
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Affected Versions
Linux:- Version 8de4a1c8164e5b2e40d1df764840a31de983f40b and below 94ade38f317ea086a181db0e6b69c574b3b70a5e is affected.
- Version 8de4a1c8164e5b2e40d1df764840a31de983f40b and below 9560e6fee887a9594a89fa265b5b9c79b1591803 is affected.
- Version 8de4a1c8164e5b2e40d1df764840a31de983f40b and below 9a12fa5213cfc391e0eed63902d3be98f0913765 is affected.
- Version 6.17 is affected.
- Before 6.17 is unaffected.
- Version 6.18.34, <= 6.18.* is unaffected.
- Version 7.0.11, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.