Secure TSC for AMD SEVSNP guests
summary
SEV‑SNP exposes secure TSC so guests can run RDTSC/RDTSCP without trusting the hypervisor: the TSC scale and offset live in the encrypted VMSA, and the AMD security processor supplies per‑CPU TSC scale/offset via SNP guest messages. A v5 patch exists; live migration logic to recalculate ratio+offset is proposed but not implemented. Tried lowering KVM clock rating as a workaround; team notes five prior migration attempts that all failed, so correctness is nontrivial.
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chapters (8)
- 0:00Introduction to TSC
- 1:49Secure TSC in SEV-SNP
- 3:12Live migration challenges
- 4:41Secure TSC boot flow
- 6:36Clock source integration
- 7:18Guest feature detection
- 9:52Performance and paravisor concerns
- 10:39VMPL transition optimization
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