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hyperv: fix SynIC SINT assertion failure on guest reset

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Resetting a guest that has Hyper-V VMBus support enabled triggers a QEMU
assertion failure:
hw/hyperv/hyperv.c:131: synic_reset: Assertion `QLIST_EMPTY(&synic->sint_routes)' failed.

This happens both on normal guest reboot or when using "system_reset" HMP
command.

The failing assertion was introduced by commit 64ddecc88b ("hyperv: SControl is optional to enable SynIc")
to catch dangling SINT routes on SynIC reset.

The root cause of this problem is that the SynIC itself is reset before
devices using SINT routes have chance to clean up these routes.

Since there seems to be no existing mechanism to force reset callbacks (or
methods) to be executed in specific order let's use a similar method that
is already used to reset another interrupt controller (APIC) after devices
have been reset - by invoking the SynIC reset from the machine reset
handler via a new x86_cpu_after_reset() function co-located with
the existing x86_cpu_reset() in target/i386/cpu.c.
Opportunistically move the APIC reset handler there, too.

Fixes: 64ddecc88b ("hyperv: SControl is optional to enable SynIc") # exposed the bug
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <cb57cee2e29b20d06f81dce054cbcea8b5d497e8.1664552976.git.maciej.szmigiero@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Maciej S. Szmigiero 2022-09-30 17:52:03 +02:00 • committed by Paolo Bonzini
parent 8b5335e381
commit ec19444a53
7 changed files with 41 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

4
hw/i386/microvm.c
View file

@ -485,9 +485,7 @@ static void microvm_machine_reset(MachineState *machine)
CPU_FOREACH(cs) {
cpu = X86_CPU(cs);
if (cpu->apic_state) {
device_legacy_reset(cpu->apic_state);
}
x86_cpu_after_reset(cpu);
}
}

5
hw/i386/pc.c
View file

@ -92,6 +92,7 @@
#include "hw/virtio/virtio-mem-pci.h"
#include "hw/mem/memory-device.h"
#include "sysemu/replay.h"
#include "target/i386/cpu.h"
#include "qapi/qmp/qerror.h"
#include "e820_memory_layout.h"
#include "fw_cfg.h"
@ -1859,9 +1860,7 @@ static void pc_machine_reset(MachineState *machine)
CPU_FOREACH(cs) {
cpu = X86_CPU(cs);
if (cpu->apic_state) {
device_legacy_reset(cpu->apic_state);
}
x86_cpu_after_reset(cpu);
}
}