[PATCH 09/15] KVM: ARM: Inject IRQs and FIQs from userspace

[Will Deacon]

Hi Christoffer,

On Sat, Sep 29, 2012 at 04:50:25PM +0100, Christoffer Dall wrote:
> On Tue, Sep 25, 2012 at 11:55 AM, Will Deacon <will.deacon at arm.com> wrote:
> > On Sat, Sep 15, 2012 at 04:35:27PM +0100, Christoffer Dall wrote:
> >> diff --git a/arch/arm/include/asm/kvm.h b/arch/arm/include/asm/kvm.h
> >> index a13b582..131e632 100644
> >> --- a/arch/arm/include/asm/kvm.h
> >> +++ b/arch/arm/include/asm/kvm.h
> >> @@ -22,6 +22,7 @@
> >>  #include <asm/types.h>
> >>
> >>  #define __KVM_HAVE_GUEST_DEBUG
> >> +#define __KVM_HAVE_IRQ_LINE
> >>
> >>  #define KVM_REG_SIZE(id)                                             \
> >>       (1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
> >> @@ -85,4 +86,24 @@ struct kvm_reg_list {
> >>  #define KVM_REG_ARM_CORE             (0x0010 << KVM_REG_ARM_COPROC_SHIFT)
> >>  #define KVM_REG_ARM_CORE_REG(name)   (offsetof(struct kvm_regs, name) / 4)
> >>
> >> +/* KVM_IRQ_LINE irq field index values */
> >> +#define KVM_ARM_IRQ_TYPE_SHIFT               24
> >> +#define KVM_ARM_IRQ_TYPE_MASK                0xff
> >> +#define KVM_ARM_IRQ_VCPU_SHIFT               16
> >> +#define KVM_ARM_IRQ_VCPU_MASK                0xff
> >> +#define KVM_ARM_IRQ_NUM_SHIFT                0
> >> +#define KVM_ARM_IRQ_NUM_MASK         0xffff
> >> +
> >> +/* irq_type field */
> >> +#define KVM_ARM_IRQ_TYPE_CPU         0
> >> +#define KVM_ARM_IRQ_TYPE_SPI         1
> >> +#define KVM_ARM_IRQ_TYPE_PPI         2
> >> +
> >> +/* out-of-kernel GIC cpu interrupt injection irq_number field */
> >> +#define KVM_ARM_IRQ_CPU_IRQ          0
> >> +#define KVM_ARM_IRQ_CPU_FIQ          1
> >> +
> >> +/* Highest supported SPI, from VGIC_NR_IRQS */
> >> +#define KVM_ARM_IRQ_GIC_MAX          127
> >
> > This define, and those referring to PPIs and SPIs sound highly GIC-specific.
> > Is that really appropriate for kvm.h? Do you mandate a single GIC as the
> > only interrupt controller?
> >
> 
> you can add a another gic with another in-kernel gic emulation if
> someone makes such one that's different from the vgic specifications
> by defining another irq type.
> 
> devices must interact with a gic available in the kernel, so I think
> referring to PPIs and SPIs is very appropriate in kvm.h for a user
> space device emulation that must inject either a PPI or an SPI.
> 
> We can call them TYPE_GIC_V2_XXX or something like that if you feel
> this is cleaner.

It's more that the GIC isn't really part of the architecture, so it would be
cleaner to have the GIC-specifics separated out from the architectural part
of KVM. That will also make it easier when adding support for future
versions of the GIC.

If core KVM needs the concept of a per-cpu interrupt, just call it
IRQ_TYPE_PERCPU or something rather than PPI.

Will