kvm: x86: ignore ioapic polarity
authorGabriel L. Somlo <gsomlo@gmail.com>
Fri, 28 Feb 2014 04:06:17 +0000 (23:06 -0500)
committerPaolo Bonzini <pbonzini@redhat.com>
Thu, 13 Mar 2014 10:58:21 +0000 (11:58 +0100)
commit100943c54e0947a07d2c0185368fc2fd848f7f28
treea69aea55ffa31a8d365974f8c9217a339cdfb27f
parentfacb0139698923dc7b7d15cafbb319219969f4fd
kvm: x86: ignore ioapic polarity

Both QEMU and KVM have already accumulated a significant number of
optimizations based on the hard-coded assumption that ioapic polarity
will always use the ActiveHigh convention, where the logical and
physical states of level-triggered irq lines always match (i.e.,
active(asserted) == high == 1, inactive == low == 0). QEMU guests
are expected to follow directions given via ACPI and configure the
ioapic with polarity 0 (ActiveHigh). However, even when misbehaving
guests (e.g. OS X <= 10.9) set the ioapic polarity to 1 (ActiveLow),
QEMU will still use the ActiveHigh signaling convention when
interfacing with KVM.

This patch modifies KVM to completely ignore ioapic polarity as set by
the guest OS, enabling misbehaving guests to work alongside those which
comply with the ActiveHigh polarity specified by QEMU's ACPI tables.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Gabriel L. Somlo <somlo@cmu.edu>
[Move documentation to KVM_IRQ_LINE, add ia64. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Documentation/virtual/kvm/api.txt
arch/ia64/kvm/kvm-ia64.c
arch/x86/kvm/x86.c
include/uapi/linux/kvm.h
virt/kvm/ioapic.c