Re: [PATCH v3 8/9] arm/arm64: KVM: vgic: make number of irqs a configurable attribute

[Christoffer Dall <christoffer.dall@xxxxxxxxxx>]

On Tue, Jul 08, 2014 at 12:09:07PM +0100, Marc Zyngier wrote:
> In order to make the number of interrupt configurable, use the new
                                 interrupts
> fancy device management API to add KVM_DEV_ARM_VGIC_GRP_NR_IRQS as
> a VGIC configurable attribute.
> 
> Userspace can now specify the exact size of the GIC (by increments
> of 32 interrupts).
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
>  arch/arm/include/uapi/asm/kvm.h   |  1 +
>  arch/arm64/include/uapi/asm/kvm.h |  1 +
>  virt/kvm/arm/vgic.c               | 29 +++++++++++++++++++++++++++++
>  3 files changed, 31 insertions(+)
> 
> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
> index e6ebdd3..8b51c1a 100644
> --- a/arch/arm/include/uapi/asm/kvm.h
> +++ b/arch/arm/include/uapi/asm/kvm.h
> @@ -173,6 +173,7 @@ struct kvm_arch_memory_slot {
>  #define   KVM_DEV_ARM_VGIC_CPUID_MASK	(0xffULL << KVM_DEV_ARM_VGIC_CPUID_SHIFT)
>  #define   KVM_DEV_ARM_VGIC_OFFSET_SHIFT	0
>  #define   KVM_DEV_ARM_VGIC_OFFSET_MASK	(0xffffffffULL << KVM_DEV_ARM_VGIC_OFFSET_SHIFT)
> +#define KVM_DEV_ARM_VGIC_GRP_NR_IRQS	3
>  
>  /* KVM_IRQ_LINE irq field index values */
>  #define KVM_ARM_IRQ_TYPE_SHIFT		24
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index e633ff8..b5cd6ed 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -159,6 +159,7 @@ struct kvm_arch_memory_slot {
>  #define   KVM_DEV_ARM_VGIC_CPUID_MASK	(0xffULL << KVM_DEV_ARM_VGIC_CPUID_SHIFT)
>  #define   KVM_DEV_ARM_VGIC_OFFSET_SHIFT	0
>  #define   KVM_DEV_ARM_VGIC_OFFSET_MASK	(0xffffffffULL << KVM_DEV_ARM_VGIC_OFFSET_SHIFT)
> +#define KVM_DEV_ARM_VGIC_GRP_NR_IRQS	3
>  
>  /* KVM_IRQ_LINE irq field index values */
>  #define KVM_ARM_IRQ_TYPE_SHIFT		24
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 708aed9..aee10da 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -2208,6 +2208,28 @@ static int vgic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
>  
>  		return vgic_attr_regs_access(dev, attr, &reg, true);
>  	}
> +	case KVM_DEV_ARM_VGIC_GRP_NR_IRQS: {
> +		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
> +		u32 val;
> +		int ret = 0;
> +
> +		if (get_user(val, uaddr))
> +			return -EFAULT;
> +
> +		if (val > 1024 || (val & 31))
> +			return -EINVAL;

                        > VGIC_MAX_IRQS ?

> +
> +		mutex_lock(&dev->kvm->lock);
> +
> +		if (vgic_initialized(dev->kvm) || dev->kvm->arch.vgic.nr_irqs)
> +			ret = -EBUSY;
> +		else
> +			dev->kvm->arch.vgic.nr_irqs = val;
> +
> +		mutex_unlock(&dev->kvm->lock);
> +
> +		return ret;
> +	}
>  
>  	}
>  
> @@ -2244,6 +2266,11 @@ static int vgic_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
>  		r = put_user(reg, uaddr);
>  		break;
>  	}
> +	case KVM_DEV_ARM_VGIC_GRP_NR_IRQS: {
> +		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
> +		r = put_user(dev->kvm->arch.vgic.nr_irqs, uaddr);
> +		break;
> +	}
>  
>  	}
>  
> @@ -2280,6 +2307,8 @@ static int vgic_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
>  	case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
>  		offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
>  		return vgic_has_attr_regs(vgic_cpu_ranges, offset);
> +	case KVM_DEV_ARM_VGIC_GRP_NR_IRQS:
> +		return 0;
>  	}
>  	return -ENXIO;
>  }
> -- 
> 2.0.0
> 

Please add Documentation of this ABI extension to:
Documentation/virtual/kvm/devices/arm-vgic.txt
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