* Suresh Siddha <suresh.b.siddha@xxxxxxxxx> wrote: > On Wed, 2009-07-01 at 06:30 -0700, Gleb Natapov wrote: > > 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). > > > > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx> > > Acked-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx> Now, since this affects core x86 APIC code non-trivially so should submitted to and go via the x86 tree. (Can prepare a special branch with just this change if KVM tree wants/needs to pull it before v2.6.32.) Ingo -- 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
