On Mon, Oct 07, 2019 at 07:11:24PM +0200, Paolo Bonzini wrote: > On 04/10/19 23:56, Sean Christopherson wrote: > > + /* > > + * The high bits contain the allowed-1 settings, i.e. features that can > > + * be turned on. The low bits contain the allowed-0 settings, i.e. > > + * features that can be turned off. Ignore the allowed-0 settings, > > + * if a feature can be turned on then it's supported. > > + */ > > + rdmsr(MSR_IA32_VMX_PINBASED_CTLS, ign, supported); > > For QEMU, we're defining a feature as supported if a feature can be > turned both on and off. Since msr_low and msr_high can be defined > respectively as must-be-one and can-be-one, the features become > "msr_high & ~msr_low". That makes sense for Qemu, but I don't think it's appropriate for this type of reporting. E.g. if EPT and Unrestricted Guest are must-be-one on a hypothetical (virtual) CPU, it'd be odd to not list them as a supported feature. For actual hardware (well, Intel hardware), as proposed it's a moot point. The only features that are must-be-one (even without "true" MSRs) and are documented in the SDM are CR3_LOAD_EXITING, CR3_STORE_EXITING, SAVE_DEBUG_CONTROLS, and LOAD_DEBUG_CONTROLS, none of which are reported in /proc/cpuinfo. > Also, shouldn't this use the "true" feature availability MSRs if available? Only if incorporating the "& ~msr_low" can-be-one logic. If a feature is considered supported if it must-be-one or can-be-one then the true MSR and vanilla MSR will yield the same feature set. > > Paolo
