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2015-03-14arm/arm64: KVM: Fix migration race in the arch timerChristoffer Dall
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>
2015-03-12arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}Christoffer Dall
We can definitely decide at run-time whether to use the GIC and timers or not, and the extra code and data structures that we allocate space for is really negligable with this config option, so I don't think it's worth the extra complexity of always having to define stub static inlines. The !CONFIG_KVM_ARM_VGIC/TIMER case is pretty much an untested code path anyway, so we're better off just getting rid of it. Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
2014-12-15arm/arm64: KVM: Require in-kernel vgic for the arch timersChristoffer Dall
It is curently possible to run a VM with architected timers support without creating an in-kernel VGIC, which will result in interrupts from the virtual timer going nowhere. To address this issue, move the architected timers initialization to the time when we run a VCPU for the first time, and then only initialize (and enable) the architected timers if we have a properly created and initialized in-kernel VGIC. When injecting interrupts from the virtual timer to the vgic, the current setup should ensure that this never calls an on-demand init of the VGIC, which is the only call path that could return an error from kvm_vgic_inject_irq(), so capture the return value and raise a warning if there's an error there. We also change the kvm_timer_init() function from returning an int to be a void function, since the function always succeeds. Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
2014-07-11arm64: KVM: allow export and import of generic timer regsAlex Bennée
For correct guest suspend/resume behaviour we need to ensure we include the generic timer registers for 64 bit guests. As CONFIG_KVM_ARM_TIMER is always set for arm64 we don't need to worry about null implementations. However I have re-jigged the kvm_arm_timer_set/get_reg declarations to be in the common include/kvm/arm_arch_timer.h headers. Acked-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-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>
2013-06-26ARM: KVM: Allow host virt timer irq to be different from guest timer virt irqAnup Patel
The arch_timer irq numbers (or PPI numbers) are implementation dependent, so the host virtual timer irq number can be different from guest virtual timer irq number. This patch ensures that host virtual timer irq number is read from DTB and guest virtual timer irq is determined based on vcpu target type. Signed-off-by: Anup Patel <anup.patel@linaro.org> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org> Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
2013-05-19ARM: KVM: move GIC/timer code to a common locationMarc Zyngier
As KVM/arm64 is looming on the horizon, it makes sense to move some of the common code to a single location in order to reduce duplication. The code could live anywhere. Actually, most of KVM is already built with a bunch of ugly ../../.. hacks in the various Makefiles, so we're not exactly talking about style here. But maybe it is time to start moving into a less ugly direction. The include files must be in a "public" location, as they are accessed from non-KVM files (arch/arm/kernel/asm-offsets.c). For this purpose, introduce two new locations: - virt/kvm/arm/ : x86 and ia64 already share the ioapic code in virt/kvm, so this could be seen as a (very ugly) precedent. - include/kvm/ : there is already an include/xen, and while the intent is slightly different, this seems as good a location as any Eventually, we should probably have independant Makefiles at every levels (just like everywhere else in the kernel), but this is just the first step. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>