On 13/12/16 15:58, Razvan Cojocaru wrote: > Hello, and first of all thanks for the discussion! > >> Think of it a bit more like introducing a new action emulator (name >> definitely subject to improvement), which implements things such as >> wrmsr, cpuid, pagewalk, task_switch, etc. >> >> The vmexit helpers, given decode assistance from hardware, can directly >> call action->task_switch(). If insufficient information is available >> (e.g. LMSW on AMD), the helpers invoke the instruction emulator to work >> out what to do, and the instruction emulator would invoke the action >> emulator as part of its execute phase. >> >> Wherever possible, the action emulator should be guest-neutral, and >> ideally the single point of implementation of non-architectural actions >> such as "the vm_event subsystem is interested in this." >> >>> And to be honest, on the road towards >>> completion of the emulator I think the SVM/VMX insns are pretty >>> close to the end of the priority list. >> I'd expect them to show up frequently during introspection, although >> maybe I am wrong. Razvan: Any thoughts? > I definitely think this is a good idea as far as introspection goes - > having a single contact surface with the underlying logic would be a > significant improvement. > > As for SVM/VMX instructions, we're interested in anything that is able > to trigger an EPT fault (and hence a mem_access event) - we've had our > share of adventures with VMX-specific instructions, so they're not low > priority for us.
In reality, this is any instruction if you set EPT NX on a page, I presume? Do you have stats on which instructions you most frequently have to singlestep because of lack of emulator support, or is the spread essentially random? ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
