KVM: lapic: stop advertising DIRECTED_EOI when in-kernel IOAPIC is in use

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Devices which use level-triggered interrupts under Windows 2016 with
Hyper-V role enabled don't work: Windows disables EOI broadcast in SPIV
unconditionally. Our in-kernel IOAPIC implementation emulates an old IOAPIC
version which has no EOI register so EOI never happens.

The issue was discovered and discussed a while ago:
https://www.spinics.net/lists/kvm/msg148098.html

While this is a guest OS bug (it should check that IOAPIC has the required
capabilities before disabling EOI broadcast) we can workaround it in KVM:
advertising DIRECTED_EOI with in-kernel IOAPIC makes little sense anyway.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

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Vitaly Kuznetsov 2018-02-09 14:01:33 +01:00 • committed by Paolo Bonzini

parent c51eb52b8f

commit 0bcc3fb95b

1 changed files with 9 additions and 1 deletions

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arch/x86/kvm/lapic.c

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