rr (http://rr-project.org/), a userspace record-and-replay reverse- execution debugger, would like to trap and emulate the CPUID instruction. This would allow us to a) mask away certain hardware features that rr does not support (e.g. RDRAND) and b) enable trace portability across machines by providing constant results. Newer Intel CPUs (Ivy Bridge and later) can fault when CPUID is executed at CPL > 0. Expose this capability to userspace as a new pair of arch_prctls, ARCH_GET_CPUID and ARCH_SET_CPUID, with two values, ARCH_CPUID_ENABLE and ARCH_CPUID_SIGSEGV. Since v9: Patch 7: KVM: x86: virtualize cpuid faulting - Fixed wrong condition when testing for a hypervisor disabling cpuid faulting while it is active. - Now stores MSRs as u64 for future extensibility. - Added cpuid_fault_enabled and supports_cpuid_fault helper functions. - Style nits. -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
