2ec282b8ea
Add following bits related Speculative Return Stack Overflow (SRSO). Guests can make use of these bits if supported. These bits are reported via CPUID Fn8000_0021_EAX. =================================================================== Bit Feature Description =================================================================== 27 SBPB Indicates support for the Selective Branch Predictor Barrier. 28 IBPB_BRTYPE MSR_PRED_CMD[IBPB] flushes all branch type predictions. 29 SRSO_NO Not vulnerable to SRSO. 30 SRSO_USER_KERNEL_NO Not vulnerable to SRSO at the user-kernel boundary. =================================================================== Link: https://www.amd.com/content/dam/amd/en/documents/corporate/cr/speculative-return-stack-overflow-whitepaper.pdf Link: https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/programmer-references/57238.zip Signed-off-by: Babu Moger <babu.moger@amd.com> Link: https://lore.kernel.org/r/dadbd70c38f4e165418d193918a3747bd715c5f4.1729807947.git.babu.moger@amd.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>