Re: [PATCH v3 02/12] KVM: arm/arm64: Document KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION

Christoffer Dall
2018-04-24T16:46:49Z

On Fri, Apr 13, 2018 at 10:20:48AM +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 | 25 ++++++++++++++++++++++-
> 1 file changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> index 9293b45..cbc4328 100644
> --- a/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> +++ b/Documentation/virtual/kvm/devices/arm-vgic-v3.txt
> @@ -27,9 +27,32 @@ 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

I'm not entirely sure I understand the purpose of the index field.
Isn't a redistributor region identified uniquely by its base address?

Otherwise this looks good.

Thanks,
-Christoffer

> + - 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.
> + - count encodes the number of redistributors in the region. Must be
> + greater than 0.
> + There are two 64K pages for each redistributor in the region and
> + redistributors are laid out contiguously within the region. Regions
> + are filled with redistributors in the index order. The sum of all
> + region count fields must be greater than or equal to the number of
> + VCPUs. Redistributor regions must be registered in the incremental
> + index order, starting from index 0.
> + 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.
> +
> Errors:
> -E2BIG: Address outside of addressable IPA range
> - -EINVAL: Incorrectly aligned address
> + -EINVAL: Incorrectly aligned address, bad redistributor region
> + count/index, mixed redistributor region attribute usage
> -EEXIST: Address already configured
> -ENXIO: The group or attribute is unknown/unsupported for this device
> or hardware support is missing.
> --
> 2.5.5
>