On Tue, May 06, 2014 at 04:11:46PM +0200, Antonios Motakis wrote:
> Hello Christoffer,
>
Hi Antonios,
[...]
>
> Doing this, we would have to make the implementation in vgic.c consistent with
> other IRQCHIPS, by using the irqchip.c common code and putting it behind the
> KVM IO BUS API.
>
> However this would be just the default way IRQs would be routed to
> guests. With IRQ routing the user can change this at will.
What do you mean with these two sentences?
> Since we
> don't want to keep the limitation of 256 vCPUs, we are currently
> proposing this:
This is a fair motivation, is it the only one, and does it only apply to
PPIs?
Do you imagine that SPIs always target all CPUs? Is that how it works
for GICv3?
>
> New capability: KVM_CAP_IRQ_ROUTING_PPI
>
> In addition to the existing routing entry types:
> /* gsi routing entry types */
> #define KVM_IRQ_ROUTING_IRQCHIP 1
> #define KVM_IRQ_ROUTING_MSI 2
>
> Add new routing entry type:
> #define KVM_IRQ_ROUTING_IRQCHIP_PPI 3
>
> In the kvm_irq_routing entry struct add an entry for the new union case:
> struct kvm_irq_routing_entry {
> __u32 gsi;
> __u32 type;
> __u32 flags;
> __u32 pad;
> union {
> struct kvm_irq_routing_irqchip irqchip;
> struct kvm_irq_routing_irqchip_ppi irqchip_ppi;
>
> struct kvm_irq_routing_msi msi;
> __u32 pad[8];
> } u;
> };
> The new structure may look like this:
> struct kvm_irq_routing_irqchip {
> __u32 irqchip;
> __u32 vcpu;
> __u32 pin;
> };
you mean struct kvm_irq_routing_irqchip_ppi?
>
>
> SPIs would be set the usual way via the KVM_IRQ_ROUTING_IRQCHIP type.
> PPIs would be set using the new KVM_IRQ_ROUTING_IRQCHIP_PPI type, and
> the target VCPU may be specified via __u32 vcpu.
>
> The __u32 vcpu variable would be interpreted as is currently done with
> KVM_IRQ_LINE on ARM: via kvm_get_vcpu(kvm, vcpu_idx).
>
> This way more than 256 VCPUs may be added to a system without breaking
> KVM_IRQ_LINE; it suffices to create new routing tables for the VGIC
> (the default ones will still map to only 256 VCPUs).
>
> =====================================================================
> The VFIO Side
>
> For VFIO_PLATFORM it is not a different story than what VFIO already does on
> x86. We are going to support the same API already documented in
> include/uapi/linux/vfio.h and will be part of the next version of the
> VFIO_PLATFORM patches.
>
> In this case, instead of injecting interrupts via an IOCTL, the user
> will use a eventfds to inject interrupts, and also mask/unmask them.
>
>
Thanks,
-Christoffer
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