On Tue, Jul 08, 2014 at 12:09:08PM +0100, Marc Zyngier wrote:
> The GIC CPU interface is always 4k aligned. If the host is using
> 64k pages, it is critical to place the guest's GICC interface at the
> same relative alignment as the host's GICV. Failure to do so results
> in an impossibility for the guest to deal with interrupts.
>
> Add a KVM_DEV_ARM_VGIC_GRP_ADDR_OFFSET attribute for the VGIC, allowing
> userspace to retrieve the GICV offset in a page. It becomes then trivial
> to adjust the GICC base address for the guest.
>
> Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
> ---
> arch/arm/include/uapi/asm/kvm.h | 1 +
> arch/arm64/include/uapi/asm/kvm.h | 1 +
> virt/kvm/arm/vgic.c | 7 +++++++
> 3 files changed, 9 insertions(+)
>
> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
> index 8b51c1a..056b782 100644
> --- a/arch/arm/include/uapi/asm/kvm.h
> +++ b/arch/arm/include/uapi/asm/kvm.h
> @@ -174,6 +174,7 @@ struct kvm_arch_memory_slot {
> #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
> +#define KVM_DEV_ARM_VGIC_GRP_ADDR_OFFSET 4
>
> /* 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 b5cd6ed..5513de4 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -160,6 +160,7 @@ struct kvm_arch_memory_slot {
> #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
> +#define KVM_DEV_ARM_VGIC_GRP_ADDR_OFFSET 4
>
> /* 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 aee10da..1e60981 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -2271,6 +2271,12 @@ static int vgic_get_attr(struct kvm_device *dev,
> struct kvm_device_attr *attr)
> r = put_user(dev->kvm->arch.vgic.nr_irqs, uaddr);
> break;
> }
> + case KVM_DEV_ARM_VGIC_GRP_ADDR_OFFSET: {
> + u32 __user *uaddr = (u32 __user *)(long)attr->addr;
> + u32 val = vgic->vcpu_base & ~PAGE_MASK;
> + r = put_user(val, uaddr);
> + break;
> + }
>
> }
>
> @@ -2308,6 +2314,7 @@ static int vgic_has_attr(struct kvm_device *dev, struct
> kvm_device_attr *attr)
> 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:
> + case KVM_DEV_ARM_VGIC_GRP_ADDR_OFFSET:
> return 0;
> }
> return -ENXIO;
> --
> 2.0.0
>
Also here, add documentation to the fancy ABI:
Documentation/virtual/kvm/devices/arm-vgic.txt
When rebased onto the recent patches this will never return anything
else than 0 right? Otherwise KVM would have failed to initialize and
bailed out. What is our solution for this problem again?
-Christoffer
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