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SubjectRe: [RFC v2 02/12] KVM: arm/arm64: Document KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION
Hi Eric,

On Tue, Mar 27, 2018 at 04:04:06PM +0200, Eric Auger wrote:
> We introduce a new KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION attribute in
> KVM_DEV_ARM_VGIC_GRP_ADDR group. It allows userspace to provide the
> base address and size of a redistributor region
>
> Compared to KVM_VGIC_V3_ADDR_TYPE_REDIST, this new attribute allows
> to declare several separate redistributor regions.
>
> So the whole redist space does not need to be contiguous anymore.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> Documentation/virtual/kvm/devices/arm-vgic-v3.txt | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> index 9293b45..0ded904 100644
> --- a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> +++ b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> @@ -27,6 +27,24 @@ Groups:
> VCPU and all of the redistributor pages are contiguous.
> Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
> This address needs to be 64K aligned.
> +
> + KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION (rw, 64-bit)
> + The attr field of kvm_device_attr encodes 3 values:
> + bits: | 63 .... 52 | 51 .... 16 | 15 - 12 |11 - 0
> + values: | count | base | flags | index
> + - index encodes the unique redistributor region index
> + - flags: reserved for future use, currently 0
> + - base field encodes bits [51:16] of the guest physical base address
> + of the first redistributor in the region. There are two 64K pages
> + for each VCPU and all of the redistributor pages are contiguous

should this be two 64K pages for the number of redistributors in this
region as specified by count ?

> + within the redistributor region.
> + - count encodes the number of redistributors in the region.

I assume it's implied that the user must register a total number of
redistributors across all the regions that matches the number of vcpus,
and that otherwise something bad happens?

> + Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
> +
> + It is invalid to mix calls with KVM_VGIC_V3_ADDR_TYPE_REDIST and
> + KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION attributes. When attempted an
> + -EINVAL error is returned.
> +
> Errors:
> -E2BIG: Address outside of addressable IPA range
> -EINVAL: Incorrectly aligned address
> --
> 2.5.5
>

Thanks,
-Christoffer

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