diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2019-04-02 10:02:15 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-05-17 15:19:39 +0200 |
| commit | 958a01dab8e02fc49f4fd619fad8c82a1108afdb (patch) | |
| tree | cdd63e978ad652d0d33686b2804a7817125d7468 /include/hw | |
| parent | 29de2804014097f8d0e6eaec3318164405afe317 (diff) | |
| download | qemu-958a01dab8e02fc49f4fd619fad8c82a1108afdb.zip | |
ioapic: allow buggy guests mishandling level-triggered interrupts to make progress
It was found that Hyper-V 2016 on KVM in some configurations (q35 machine +
piix4-usb-uhci) hangs on boot. Root-cause was that one of Hyper-V
level-triggered interrupt handler performs EOI before fixing the cause of
the interrupt. This results in IOAPIC keep re-raising the level-triggered
interrupt after EOI because irq-line remains asserted.
Gory details: https://www.spinics.net/lists/kvm/msg184484.html
(the whole thread).
Turns out we were dealing with similar issues before; in-kernel IOAPIC
implementation has commit 184564efae4d ("kvm: ioapic: conditionally delay
irq delivery duringeoi broadcast") which describes a very similar issue.
Steal the idea from the above mentioned commit for IOAPIC implementation in
QEMU. SUCCESSIVE_IRQ_MAX_COUNT, delay and the comment are borrowed as well.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20190402080215.10747-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/hw')
| -rw-r--r-- | include/hw/i386/ioapic_internal.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/hw/i386/ioapic_internal.h b/include/hw/i386/ioapic_internal.h index 9848f391bb..07002f9662 100644 --- a/include/hw/i386/ioapic_internal.h +++ b/include/hw/i386/ioapic_internal.h @@ -96,6 +96,7 @@ typedef struct IOAPICCommonClass { SysBusDeviceClass parent_class; DeviceRealize realize; + DeviceUnrealize unrealize; void (*pre_save)(IOAPICCommonState *s); void (*post_load)(IOAPICCommonState *s); } IOAPICCommonClass; @@ -111,6 +112,8 @@ struct IOAPICCommonState { uint8_t version; uint64_t irq_count[IOAPIC_NUM_PINS]; int irq_level[IOAPIC_NUM_PINS]; + int irq_eoi[IOAPIC_NUM_PINS]; + QEMUTimer *delayed_ioapic_service_timer; }; void ioapic_reset_common(DeviceState *dev); |