Gleb Natapov <gleb@xxxxxxxxxx> writes: > KVM would like to provide x2APIC interface to a guest without emulating > interrupt remapping device. The reason KVM prefers guest to use x2APIC > is that x2APIC interface is better virtualizable and provides better > performance than mmio xAPIC interface: > > - msr exits are faster than mmio (no page table walk, emulation) > - no need to read back ICR to look at the busy bit > - one 64 bit ICR write instead of two 32 bit writes > - shared code with the Hyper-V paravirt interface > > Included patch changes x2APIC enabling logic to enable it even if IR > initialization failed, but kernel runs under KVM and no apic id is > greater than 255 (if there is one spec requires BIOS to move to x2apic > mode before starting an OS). How common is hotplug hardware in kvm? In particular hotplug cpus? To support that seriously you need interrupt remapping. Eric -- 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
