[PATCH 28/45] KVM: arm/arm64: vgic-new: Add GICv3 SGI system register trap handler

[Peter Maydell]

On 15 April 2016 at 18:11, Andre Przywara <andre.przywara at arm.com> wrote:
> In contrast to GICv2 SGIs in a GICv3 implementation are not triggered
> by a MMIO write, but with a system register write. KVM knows about
> that register already, we just need to implement the handler and wire
> it up to the core KVM/ARM code.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
>
> Changelog RFC..v1:
> - add comment about SGI_AFFINITY_LEVEL macro

> +/**
> + * vgic_v3_dispatch_sgi - handle SGI requests from VCPUs
> + * @vcpu: The VCPU requesting a SGI
> + * @reg: The value written into the ICC_SGI1R_EL1 register by that VCPU
> + *
> + * With GICv3 (and ARE=1) CPUs trigger SGIs by writing to a system register.
> + * This will trap in sys_regs.c and call this function.
> + * This ICC_SGI1R_EL1 register contains the upper three affinity levels of the
> + * target processors as well as a bitmask of 16 Aff0 CPUs.
> + * If the interrupt routing mode bit is not set, we iterate over all VCPUs to
> + * check for matching ones. If this bit is set, we signal all, but not the
> + * calling VCPU.
> + */

No ICC_SGI0R_EL1, ICC_ASGI1R_EL1 ?

> +void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg)
> +{
> +       struct kvm *kvm = vcpu->kvm;
> +       struct kvm_vcpu *c_vcpu;
> +       u16 target_cpus;
> +       u64 mpidr;
> +       int sgi, c;
> +       int vcpu_id = vcpu->vcpu_id;
> +       bool broadcast;
> +
> +       sgi = (reg & ICC_SGI1R_SGI_ID_MASK) >> ICC_SGI1R_SGI_ID_SHIFT;
> +       broadcast = reg & BIT(ICC_SGI1R_IRQ_ROUTING_MODE_BIT);
> +       target_cpus = (reg & ICC_SGI1R_TARGET_LIST_MASK) >> ICC_SGI1R_TARGET_LIST_SHIFT;
> +       mpidr = SGI_AFFINITY_LEVEL(reg, 3);
> +       mpidr |= SGI_AFFINITY_LEVEL(reg, 2);
> +       mpidr |= SGI_AFFINITY_LEVEL(reg, 1);
> +
> +       /*
> +        * We iterate over all VCPUs to find the MPIDRs matching the request.
> +        * If we have handled one CPU, we clear its bit to detect early
> +        * if we are already finished. This avoids iterating through all
> +        * VCPUs when most of the times we just signal a single VCPU.
> +        */
> +       kvm_for_each_vcpu(c, c_vcpu, kvm) {
> +               struct vgic_irq *irq;
> +
> +               /* Exit early if we have dealt with all requested CPUs */
> +               if (!broadcast && target_cpus == 0)
> +                       break;
> +
> +               /* Don't signal the calling VCPU */
> +               if (broadcast && c == vcpu_id)
> +                       continue;
> +
> +               if (!broadcast) {
> +                       int level0;
> +
> +                       level0 = match_mpidr(mpidr, target_cpus, c_vcpu);
> +                       if (level0 == -1)
> +                               continue;
> +
> +                       /* remove this matching VCPU from the mask */
> +                       target_cpus &= ~BIT(level0);
> +               }

I think you need a check in here that the SGI is actually configured
to be the group that's been requested.

> +
> +               irq = vgic_get_irq(vcpu->kvm, c_vcpu, sgi);
> +
> +               spin_lock(&irq->irq_lock);
> +               irq->pending = true;
> +
> +               vgic_queue_irq_unlock(vcpu->kvm, irq);
> +       }
> +}
>  #endif
> --
> 2.7.3

thanks
-- PMM