APICv traps register writes, so we can't retrieve previous value, but our code depends on detecting changes.
Apart from disabling APIC register virtualization, we can detect the change by using extra memory. One value history is enough, but we still don't want to keep it for every APIC register, for performance reasons. This leaves us with either a new framework, or exceptions ... The latter options fits KVM's path better [1,2]. And when we already mirror a part of registers, optimizing access is acceptable [3]. (Squashed to keep bisecters happy.) --- Radim Krčmář (3): KVM: x86: detect SPIV changes under APICv KVM: x86: detect LVTT changes under APICv KVM: x86: optimize some accesses to LVTT and SPIV arch/x86/kvm/lapic.c | 32 +++++++++++++++++--------------- arch/x86/kvm/lapic.h | 8 +++++--- 2 files changed, 22 insertions(+), 18 deletions(-) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
