On 7 August 2012 14:59, Avi Kivity <avi@xxxxxxxxxx> wrote: > On 08/06/2012 08:20 PM, Peter Maydell wrote: >> On 3 July 2012 10:01, Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx> wrote: >>> From: Christoffer Dall <cdall@xxxxxxxxxxxxxxx> >>> >>> Userspace can inject IRQs and FIQs through the KVM_IRQ_LINE VM ioctl. >>> This ioctl is used since the sematics are in fact two lines that can be >>> either raised or lowered on the VCPU - the IRQ and FIQ lines. >>> >>> KVM needs to know which VCPU it must operate on and whether the FIQ or >>> IRQ line is raised/lowered. Hence both pieces of information is packed >>> in the kvm_irq_level->irq field. The irq fild value will be: >>> IRQ: vcpu_index << 1 >>> FIQ: (vcpu_index << 1) | 1 >>> >>> This is documented in Documentation/kvm/api.txt. >> >> It occurred to me that rather than encoding the CPU index in the IRQ >> field value, maybe we should just use the per-vcpu version of >> KVM_IRQ_LINE the same way we do for injecting the per-CPU lines >> of the in-kernel (V)GIC ? > > What do you mean by "per-vcpu version of KVM_IRQ_LINE"? The ARM VGIC implementation implements "I need to raise per-CPU interrupt X" by providing a vcpu ioctl KVM_IRQ_LINE (this is in addition to the vm ioctl KVM_IRQ_LINE which it uses for "I need to raise the external interrupt X"). The patch updating the API documentation is this one: https://lists.cs.columbia.edu/pipermail/kvmarm/2012-July/001206.html >> (The subtext here is that it would be cool to have QEMU's >> generic interrupt handling code for KVM be able to say "if >> you do a cpu_interrupt()/cpu_reset_interrupt() and async >> interrupt delivery is enabled then just do the per-vcpu ioctl". >> Then there wouldn't need to be any kvm-specific code in >> hw/arm_pic.c at all...) > > If you mean "vcpu ioctl", then no, vcpu ioctls must be called from the > vcpu thread. That's a shame, because it's the obvious interface for "do something to this specific CPU". -- PMM -- 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
