Hi Marc,
On 06/08/2015 06:04 PM, Marc Zyngier wrote:
> To allow a HW interrupt to be injected into a guest, we lookup the
> guest virtual interrupt in the irq_phys_map rbtree, and if we have
> a match, encode both interrupts in the LR.
>
> We also mark the interrupt as "active" at the host distributor level.
>
> On guest EOI on the virtual interrupt, the host interrupt will be
> deactivated.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> virt/kvm/arm/vgic.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 68 insertions(+), 3 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index c6604f2..495ac7d 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -1120,6 +1120,26 @@ static void vgic_queue_irq_to_lr(struct kvm_vcpu *vcpu, int irq,
> if (!vgic_irq_is_edge(vcpu, irq))
> vlr.state |= LR_EOI_INT;
>
> + if (vlr.irq >= VGIC_NR_SGIS) {
> + struct irq_phys_map *map;
> + map = vgic_irq_map_search(vcpu, irq);
> +
> + if (map) {
> + int ret;
> +
> + BUG_ON(!map->active);
> + vlr.hwirq = map->phys_irq;
> + vlr.state |= LR_HW;
> + vlr.state &= ~LR_EOI_INT;
> +
> + ret = irq_set_irqchip_state(map->irq,
> + IRQCHIP_STATE_ACTIVE,
> + true);
> + vgic_irq_set_queued(vcpu, irq);
> + WARN_ON(ret);
> + }
> + }
> +
> vgic_set_lr(vcpu, lr_nr, vlr);
> vgic_sync_lr_elrsr(vcpu, lr_nr, vlr);
> }
> @@ -1344,6 +1364,35 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
> return level_pending;
> }
>
> +/* Return 1 if HW interrupt went from active to inactive, and 0 otherwise */
> +static int vgic_sync_hwirq(struct kvm_vcpu *vcpu, struct vgic_lr vlr)
> +{
> + struct irq_phys_map *map;
> + int ret;
> +
> + if (!(vlr.state & LR_HW))
> + return 0;
> +
> + map = vgic_irq_map_search(vcpu, vlr.irq);
I wonder if it's safe to rely on that mapping here. Are we sure that
this hasn't changed while the VCPU was running? If I got this correctly,
currently only vcpu_reset will actually add a map entry, but I guess in
the future there will be more users.
Also we rely on the irqdomain mapping to be still the same, but that is
probably a safe assumption.
But I'd still find it more natural to use the hwirq number from the LR
at this point. Can't we use irq_find_mapping() here to learn Linux'
(current) irq number from that?
Or am I too paranoid here?
Cheers,
Andre.
> + BUG_ON(!map || !map->active);
> +
> + ret = irq_get_irqchip_state(map->irq,
> + IRQCHIP_STATE_ACTIVE,
> + &map->active);
> +
> + WARN_ON(ret);
> +
> + if (map->active) {
> + ret = irq_set_irqchip_state(map->irq,
> + IRQCHIP_STATE_ACTIVE,
> + false);
> + WARN_ON(ret);
> + return 0;
> + }
> +
> + return 1;
> +}
> +
> /* Sync back the VGIC state after a guest run */
> static void __kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
> {
> @@ -1358,14 +1407,30 @@ static void __kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
> elrsr = vgic_get_elrsr(vcpu);
> elrsr_ptr = u64_to_bitmask(&elrsr);
>
> - /* Clear mappings for empty LRs */
> - for_each_set_bit(lr, elrsr_ptr, vgic->nr_lr) {
> + /* Deal with HW interrupts, and clear mappings for empty LRs */
> + for (lr = 0; lr < vgic->nr_lr; lr++) {
> struct vgic_lr vlr;
>
> - if (!test_and_clear_bit(lr, vgic_cpu->lr_used))
> + if (!test_bit(lr, vgic_cpu->lr_used))
> continue;
>
> vlr = vgic_get_lr(vcpu, lr);
> + if (vgic_sync_hwirq(vcpu, vlr)) {
> + /*
> + * So this is a HW interrupt that the guest
> + * EOI-ed. Clean the LR state and allow the
> + * interrupt to be queued again.
> + */
> + vlr.state &= ~LR_HW;
> + vlr.hwirq = 0;
> + vgic_set_lr(vcpu, lr, vlr);
> + vgic_irq_clear_queued(vcpu, vlr.irq);
> + }
> +
> + if (!test_bit(lr, elrsr_ptr))
> + continue;
> +
> + clear_bit(lr, vgic_cpu->lr_used);
>
> BUG_ON(vlr.irq >= dist->nr_irqs);
> vgic_cpu->vgic_irq_lr_map[vlr.irq] = LR_EMPTY;
>
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