As I said... I think KVM has already added an emulated instructions enumeration API. On May 1, 2014 12:26:18 PM PDT, tytso@xxxxxxx wrote: >On Thu, May 01, 2014 at 12:02:49PM -0700, Andy Lutomirski wrote: >> >> Is RDSEED really reasonable here? Won't it slow down by several >> orders of magnitude? > >That is I think the biggest problem; RDRAND and RDSEED are fast if >they are native, but they will involve a VM exit if they need to be >emulated. So when an OS might want to use RDRAND and RDSEED might be >quite different if we know they are being emulated. > >Using the RDRAND and RDSEED "api" certainly makes sense, at least for >x86, but I suspect we might want to use a different way of signalling >that a VM guest can use RDRAND and RDSEED if they are running on a CPU >which doesn't provide that kind of access. Maybe a CPUID extended >function parameter, if one could be allocated for use by a Linux >hypervisor? > > - Ted -- Sent from my mobile phone. Please pardon brevity and lack of formatting. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
