>>> On 13.01.16 at 17:17, <andrew.coop...@citrix.com> wrote: > On 13/01/16 16:13, Jan Beulich wrote: >>>>> On 13.01.16 at 16:49, <roger....@citrix.com> wrote: >>> Hello, >>> >>> While working on a HVMlite Dom0 implementation I've found a couple of >>> loose ends with the design that I would like to comment because it's not >>> clear to me what's the best direction to take. >>> >>> 1. HVM CPUID and Dom0. >>> >>> Sadly the way CPUID is handled inside of Xen varies between PV and HVM. >>> On PV guests AFAICT we mostly do black-listing (I think this is the >>> right term), which means we pick the native CPUID result and then >>> perform a series of filter operations in order to remove features which >>> should not be exposed to a PV guest. On the other hand, for HVM guests >>> we pre-populate an array (d->arch.cpuids) during domain build time, and >>> the contents of that array is what is returned to the guest when a CPUID >>> instruction is executed. >> This d->arch.cpuids[] mechanism is common to HVM and PV; the >> exception really is Dom0. > > Dom0 is not special when it comes to cpuid, and shouldn't be treated as > such. My longter term CPUID plans will be fixing this.
In some way it is - there's no need for hiding features from it, since it can't be migrated. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
