mii/qemu
1
0
Fork 0
mirror of https://github.com/mii443/qemu.git synced 2025-12-16 17:18:49 +00:00
Code Issues Packages Projects Releases Wiki Activity

ioapic: allow buggy guests mishandling level-triggered interrupts to make progress

Browse Source 
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>
This commit is contained in:
Vitaly Kuznetsov
2019-04-02 10:02:15 +02:00
committed by Paolo Bonzini
parent 29de280401
commit 958a01dab8
3 changed files with 56 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
include/hw/i386/ioapic_internal.h
View File

@@ -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);