kernel_optimize_test/arch/arm/kvm
Christoffer Dall 1a74847885 arm/arm64: KVM: Fix migration race in the arch timer
When a VCPU is no longer running, we currently check to see if it has a
timer scheduled in the future, and if it does, we schedule a host
hrtimer to notify is in case the timer expires while the VCPU is still
not running.  When the hrtimer fires, we mask the guest's timer and
inject the timer IRQ (still relying on the guest unmasking the time when
it receives the IRQ).

This is all good and fine, but when migration a VM (checkpoint/restore)
this introduces a race.  It is unlikely, but possible, for the following
sequence of events to happen:

 1. Userspace stops the VM
 2. Hrtimer for VCPU is scheduled
 3. Userspace checkpoints the VGIC state (no pending timer interrupts)
 4. The hrtimer fires, schedules work in a workqueue
 5. Workqueue function runs, masks the timer and injects timer interrupt
 6. Userspace checkpoints the timer state (timer masked)

At restore time, you end up with a masked timer without any timer
interrupts and your guest halts never receiving timer interrupts.

Fix this by only kicking the VCPU in the workqueue function, and sample
the expired state of the timer when entering the guest again and inject
the interrupt and mask the timer only then.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
2015-03-14 13:48:00 +01:00
..
arm.c arm/arm64: KVM: Fix migration race in the arch timer 2015-03-14 13:48:00 +01:00
coproc_a7.c arm/arm64: KVM: Use set/way op trapping to track the state of the caches 2015-01-29 23:24:56 +01:00
coproc_a15.c arm/arm64: KVM: Use set/way op trapping to track the state of the caches 2015-01-29 23:24:56 +01:00
coproc.c arm/arm64: KVM: Use set/way op trapping to track the state of the caches 2015-01-29 23:24:56 +01:00
coproc.h arm/arm64: KVM: Use set/way op trapping to track the state of the caches 2015-01-29 23:24:56 +01:00
emulate.c
guest.c arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER} 2015-03-12 15:15:27 +01:00
handle_exit.c ARM: KVM: extend WFI tracepoint to differentiate between wfi and wfe 2015-01-15 13:12:27 +01:00
init.S ARM/ARM64: KVM: Nuke Hyp-mode tlbs before enabling MMU 2014-08-29 11:53:26 +02:00
interrupts_head.S arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER} 2015-03-12 15:15:27 +01:00
interrupts.S KVM: arm: Add ARMv7 API to flush TLBs 2015-01-16 14:40:14 +01:00
Kconfig KVM: arm/arm64: add irqfd support 2015-03-12 15:15:34 +01:00
Makefile KVM: arm/arm64: add irqfd support 2015-03-12 15:15:34 +01:00
mmio.c arm/arm64: KVM: avoid unnecessary guest register mangling on MMIO read 2014-11-25 13:57:28 +00:00
mmu.c arm/arm64: KVM: Optimize handling of Access Flag faults 2015-03-12 22:34:49 +01:00
perf.c
psci.c arm/arm64: KVM: rework MPIDR assignment and add accessors 2015-01-20 18:25:17 +01:00
reset.c
trace.h arm/arm64: KVM: Optimize handling of Access Flag faults 2015-03-12 22:34:49 +01:00