[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 0/4] Expose HW APIC virtualization support to HVM guests
On 11/03/14 03:53, Boris Ostrovsky wrote: > > Version 2: > * Added ability to specify hypervisor CPUID leaves in config file (this > requires > new sysctl) > * Use 2 bits to indicate what is supported --- one for APIC memory access and > the > other for x2APIC. Still not sure whether virtual interrupt delivery should > be > exposed as well. > > > > HVM guests running on HW that supports HW APIC virtualization features > (APIC-register virtualization, virtual interrupt delivery, etc) may > want to use APIC instead of hvm_pirqs. Since we are not guaranteed to > have these features on VMX (for example, there is a boot option to > turn it off) and there is no such support on SVM we need to make the > guest aware that its APIC accesses may not be so bad. > > CPUID seems to be a good way to provide this info to the guest. It's seems a bit odd to use a Xen-specific (?) CPUID leaf to report that the guest should use a bare-metal feature -- that's the default behaviour of a HVM guest. I think it makes more sense to hint that the guest that a PV alternate is available and then omit this hint if using a virtualized APIC performs better. David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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