kernel/linux.git/virt/kvm/arm/arch_timer.c, branch v4.9.136

KVM: arm/arm64: Fix occasional warning from the timer work function

2017-12-09T21:01:52+00:00

[ Upstream commit 63e41226afc3f7a044b70325566fa86ac3142538 ] When a VCPU blocks (WFI) and has programmed the vtimer, we program a soft timer to expire in the future to wake up the vcpu thread when appropriate. Because such as wake up involves a vcpu kick, and the timer expire function can get called from interrupt context, and the kick may sleep, we have to schedule the kick in the work function. The work function currently has a warning that gets raised if it turns out that the timer shouldn't fire when it's run, which was added because the idea was that in that case the work should never have been cancelled. However, it turns out that this whole thing is racy and we can get spurious warnings. The problem is that we clear the armed flag in the work function, which may run in parallel with the kvm_timer_unschedule->timer_disarm() call. This results in a possible situation where the timer_disarm() call does not call cancel_work_sync(), which effectively synchronizes the completion of the work function with running the VCPU. As a result, the VCPU thread proceeds before the work function completees, causing changes to the timer state such that kvm_timer_should_fire(vcpu) returns false in the work function. All we do in the work function is to kick the VCPU, and an occasional rare extra kick never harmed anyone. Since the race above is extremely rare, we don't bother checking if the race happens but simply remove the check and the clearing of the armed flag from the work function. Reported-by: Matthias Brugger Reviewed-by: Marc Zyngier Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: ARM: cleanup kvm_timer_hyp_init

2016-09-08T10:54:00+00:00

Remove two unnecessary labels now that kvm_timer_hyp_init is not creating its own workqueue anymore. Signed-off-by: Paolo Bonzini Signed-off-by: Christoffer Dall

KVM: Remove deprecated create_singlethread_workqueue

2016-09-07T17:34:28+00:00

The workqueue "irqfd_cleanup_wq" queues a single work item &irqfd->shutdown and hence doesn't require ordering. It is a host-wide workqueue for issuing deferred shutdown requests aggregated from all vm* instances. It is not being used on a memory reclaim path. Hence, it has been converted to use system_wq. The work item has been flushed in kvm_irqfd_release(). The workqueue "wqueue" queues a single work item &timer->expired and hence doesn't require ordering. Also, it is not being used on a memory reclaim path. Hence, it has been converted to use system_wq. System workqueues have been able to handle high level of concurrency for a long time now and hence it's not required to have a singlethreaded workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue created with create_singlethread_workqueue(), system_wq allows multiple work items to overlap executions even on the same CPU; however, a per-cpu workqueue doesn't have any CPU locality or global ordering guarantee unless the target CPU is explicitly specified and thus the increase of local concurrency shouldn't make any difference. Signed-off-by: Bhaktipriya Shridhar Signed-off-by: Paolo Bonzini

KVM: arm/arm64: timer: Workaround misconfigured timer interrupt

2016-08-17T10:23:47+00:00

Similarily to f005bd7e3b84 ("clocksource/arm_arch_timer: Force per-CPU interrupt to be level-triggered"), make sure we can survive an interrupt that has been misconfigured as edge-triggered by forcing it to be level-triggered (active low is assumed, but the GIC doesn't really care whether this is high or low). Hopefully, the amount of shouting in the kernel log will convince the user to do something about their firmware. Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall

arm/kvm/arch_timer: Convert to hotplug state machine

2016-07-15T08:40:27+00:00

Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Signed-off-by: Richard Cochran Signed-off-by: Anna-Maria Gleixner Reviewed-by: Sebastian Andrzej Siewior Cc: Christoffer Dall Cc: Gleb Natapov Cc: Linus Torvalds Cc: Marc Zyngier Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Radim Krcmar Cc: Thomas Gleixner Cc: kvm@vger.kernel.org Cc: kvmarm@lists.cs.columbia.edu Cc: linux-arm-kernel@lists.infradead.org Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153336.634155707@linutronix.de Signed-off-by: Ingo Molnar

KVM: arm/arm64: Move timer IRQ map to latest possible time

2016-05-20T13:39:41+00:00

We are about to modify the VGIC to allocate all data structures dynamically and store mapped IRQ information on a per-IRQ struct, which is indeed allocated dynamically at init time. Therefore, we cannot record the mapped IRQ info from the timer at timer reset time like it's done now, because VCPU reset happens before timer init. A possible later time to do this is on the first run of a per VCPU, it just requires us to move the enable state to be a per-VCPU state and do the lookup of the physical IRQ number when we are about to run the VCPU. Signed-off-by: Christoffer Dall Signed-off-by: Andre Przywara

KVM: arm/arm64: vgic: Remove irq_phys_map from interface

2016-05-20T13:39:40+00:00

Now that the virtual arch timer does not care about the irq_phys_map anymore, let's rework kvm_vgic_map_phys_irq() to return an error value instead. Any reference to that mapping can later be done by passing the correct combination of VCPU and virtual IRQ number. This makes the irq_phys_map handling completely private to the VGIC code. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall

KVM: arm/arm64: arch_timer: Remove irq_phys_map

2016-05-20T13:39:39+00:00

Now that the interface between the arch timer and the VGIC does not require passing the irq_phys_map entry pointer anymore, let's remove it from the virtual arch timer and use the virtual IRQ number instead directly. The remaining pointer returned by kvm_vgic_map_phys_irq() will be removed in the following patch. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall

KVM: arm/arm64: Remove the IRQ field from struct irq_phys_map

2016-05-20T13:39:39+00:00

The communication of a Linux IRQ number from outside the VGIC to the vgic was a leftover from the day when the vgic code cared about how a particular device injects virtual interrupts mapped to a physical interrupt. We can safely remove this notion, leaving all physical IRQ handling to be done in the device driver (the arch timer in this case), which makes room for a saner API for the new VGIC. Signed-off-by: Christoffer Dall Signed-off-by: Andre Przywara Reviewed-by: Eric Auger

KVM: arm/arm64: vgic: avoid map in kvm_vgic_unmap_phys_irq()

2016-05-20T13:39:38+00:00

kvm_vgic_unmap_phys_irq() only needs the virtual IRQ number, so let's just pass that between the arch timer and the VGIC to get rid of the irq_phys_map pointer. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall