Messages in this thread | | | Date | Fri, 3 Dec 2010 11:29:40 +0000 | From | Stefano Stabellini <> | Subject | Re: [PATCH] xen: HVM X2APIC support |
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On Fri, 3 Dec 2010, Sheng Yang wrote: > I suppose only HVM guest without XENFEAT_hvm_pirqs may need this. But does this > code covered PV guest as well? We don't need cover them. >
We can add a check on xen_pv_domain() to rule PV guests out.
> > } > > #else > > static inline bool xen_para_available(void) > > { > > return (xen_cpuid_base() != 0); > > } > > #endif > > > > > > This is assuming that enabling x2apic doesn't prevent Linux from > > receiving evtchns either using the callback vector mechanism or the > > legacy platform-pci interrupt. > > I suppose only legacy platform-pci would need this, because it would use lapic. > Callback vector method would use evtchn so this won't be enabled. >
Right, should add a check on xen_have_vector_callback too.
> > Finally when running as dom0 would this feature create problems in the > > presence of a real x2apic? > > I don't think this can be enabled on dom0. > > This one target on HVM domain, maybe also PVHVM domain without XENFEAT_hvm_pirqs, > but not the domains using evtchn. >
Ok, a check on xen_pv_domain() will disable x2apic for both pv guests and dom0:
#ifdef CONFIG_XEN_PVHVM static inline bool xen_para_available(void) { if (xen_pv_domain()) return 0; if (xen_cpuid_base() != 0 && xen_feature(XENFEAT_hvm_pirqs) && xen_have_vector_callback) return 0; else return 1; }
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