Hi Marc, On 06/08/2015 07:03 PM, Marc Zyngier wrote: > From day 1, our timer code has been using a terrible hack: whenever > the guest is scheduled with a timer interrupt pending (i.e. the HW > timer has expired), we restore the timer state with the MASK bit set, > in order to avoid the physical interrupt to fire again. And again. And > again... > > This is absolutely silly, for at least two reasons: > > - This relies on the device (the timer) having a mask bit that we can > play with. Not all devices are built like this. > > - This expects some behaviour of the guest that only works because the > both the kernel timer code and the KVM counterpart have been written > by the same idiot (the idiot being me). > > The One True Way is to set the GIC active bit when injecting the > interrupt, and to context-switch across the world switch. This is what > this series implements. > > We introduce a relatively simple infrastructure enabling the mapping > of a virtual interrupt with its physical counterpart: > > - Whenever an virtual interrupt is injected, we look it up in an > rbtree. If we have a match, the interrupt is injected with the HW > bit set in the LR, together with the physical interrupt. > > - Across the world switch, we save/restore the active state for these > interrupts using the irqchip_state API. > > - On guest EOI, the HW interrupt is automagically deactivated by the > GIC, allowing the interrupt to be resampled. I am lost about the status of the irqchip part, allowing EOImode=1 and only dropping the prio for physical forwarded IRQs: http://lkml.iu.edu/hypermail/linux/kernel/1410.3/00913.html Doesn't this series also depend on those patches or did I miss something on the ML? Best Regards Eric > > The timer code is slightly modified to set the active state at the > same time as the injection. > > The last patch also allows non-shared devices to have their interrupt > deactivated the same way (in this case we do not context-switch the > active state). This is the first step in the long overdue direction of > the mythical IRQ forwarding thing... > > This series is based on v4.1-rc7, and has been tested on Juno (GICv2) > and the FVP Base model (GICv3 host, both GICv2 and GICv3 guests). I'd > appreciate any form of testing, specially in the context of guest > migration (there is obviously some interesting stuff there...). > > The code is otherwise available at > git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/active-timer > > Marc Zyngier (10): > arm/arm64: KVM: Fix ordering of timer/GIC on guest entry > arm/arm64: KVM: Move vgic handling to a non-preemptible section > KVM: arm/arm64: vgic: Convert struct vgic_lr to use bitfields > KVM: arm/arm64: vgic: Allow HW irq to be encoded in LR > KVM: arm/arm64: vgic: Relax vgic_can_sample_irq for edge IRQs > KVM: arm/arm64: vgic: Allow dynamic mapping of physical/virtual > interrupts > KVM: arm/arm64: vgic: Allow HW interrupts to be queued to a guest > KVM: arm/arm64: vgic: Add vgic_{get,set}_phys_irq_active > KVM: arm/arm64: timer: Allow the timer to control the active state > KVM: arm/arm64: vgic: Allow non-shared device HW interrupts > > arch/arm/kvm/arm.c | 21 +++- > include/kvm/arm_arch_timer.h | 3 + > include/kvm/arm_vgic.h | 31 +++++- > include/linux/irqchip/arm-gic-v3.h | 3 + > include/linux/irqchip/arm-gic.h | 3 +- > virt/kvm/arm/arch_timer.c | 13 ++- > virt/kvm/arm/vgic-v2.c | 16 ++- > virt/kvm/arm/vgic-v3.c | 21 +++- > virt/kvm/arm/vgic.c | 206 ++++++++++++++++++++++++++++++++++++- > 9 files changed, 300 insertions(+), 17 deletions(-) > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
