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kvm: x86: ignore ioapic polarity

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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>
This commit is contained in:
Gabriel L. Somlo
2014-02-27 23:06:17 -05:00
committed by Paolo Bonzini
parent facb013969
commit 100943c54e
5 changed files with 18 additions and 2 deletions
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1
arch/ia64/kvm/kvm-ia64.c
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@@ -199,6 +199,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_IRQCHIP:
case KVM_CAP_MP_STATE:
case KVM_CAP_IRQ_INJECT_STATUS:
case KVM_CAP_IOAPIC_POLARITY_IGNORED:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO: