Database/Kernel, userspace & hypervisor
Linux kernel (arch/x86/kvm/svm): VMLOAD/VMSAVE executed by an L2 guest and not intercepted by L1 were emulated against
Impact
VMLOAD/VMSAVE executed by an L2 guest and not intercepted by L1 were emulated against vmcb02 instead of vmcb01, so the nested guest reads and overwrites the wrong control block - segment bases, TR/LDTR, and the SYSCALL/SYSENTER MSR state belonging to the other level. A workload inside a nested guest can harvest or corrupt its hypervisor's saved state in host-managed pages.
Who can reach it
Guest-driven: requires nested SVM exposed to the tenant (AMD host, kvm_amd nested=1) and an L2 running with virtual VMLOAD/VMSAVE not intercepted by L1. The instruction is executed directly by guest code - no ioctl, no host privilege.
What to do
Update to a stable kernel with the linked fix (no fixed release enumerated; take the branch carrying commit 3880e331b0b3). Interim control: withhold nested virtualization from tenant guests (kvm_amd.nested=0) or disable virtual VMLOAD/VMSAVE so the instructions always trap.
References
Related entries
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This entry is curated: imported from vendor advisories with machine assistance, not yet individually verified. Confirm against your vendor's advisory before acting, and report anything wrong.