Re: [PATCH v3 04/12] KVM: arm/arm64: Helper to locate free rdist index

Christoffer Dall
2018-04-24T21:07:04Z

On Fri, Apr 13, 2018 at 10:20:50AM +0200, Eric Auger wrote:
> We introduce vgic_v3_rdist_free_slot to help identifying
> where we can place a new 2x64KB redistributor.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> virt/kvm/arm/vgic/vgic-mmio-v3.c | 3 +--
> virt/kvm/arm/vgic/vgic-v3.c | 17 +++++++++++++++++
> virt/kvm/arm/vgic/vgic.h | 11 +++++++++++
> 3 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index d1aab18..49ca176 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -593,8 +593,7 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu)
> * function for all VCPUs when the base address is set. Just return
> * without doing any work for now.
> */
> - rdreg = list_first_entry(&vgic->rd_regions,
> - struct vgic_redist_region, list);
> + rdreg = vgic_v3_rdist_free_slot(&vgic->rd_regions);
> if (!rdreg)
> return 0;
>
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index 94de6cd..820012a 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -444,6 +444,23 @@ bool vgic_v3_check_base(struct kvm *kvm)
> return false;
> }
>
> +/**
> + * vgic_v3_rdist_free_slot - Look up registered rdist regions and identify one
> + * which has free space to put a new rdist regions

Can this structure ever be sparse or do we always find the first empty
one, as we fill them consecutively ?

I assume there is some mapping between the regions and the VCPUs'
redistributors, so perhaps the wording in this comment can be more
precise.

> + *
> + * If any, return this redist region handle, otherwise returns NULL.
> + */
> +struct vgic_redist_region *vgic_v3_rdist_free_slot(struct list_head *rd_regions)
> +{
> + struct vgic_redist_region *rdreg;
> +
> + list_for_each_entry(rdreg, rd_regions, list) {
> + if (!vgic_v3_redist_region_full(rdreg))
> + return rdreg;
> + }
> + return NULL;
> +}
> +
> int vgic_v3_map_resources(struct kvm *kvm)
> {
> int ret = 0;
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index 830e815..fea32cb 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -251,6 +251,17 @@ static inline int vgic_v3_max_apr_idx(struct kvm_vcpu *vcpu)
> }
> }
>
> +static inline bool
> +vgic_v3_redist_region_full(struct vgic_redist_region *region)
> +{
> + if (!region->count)
> + return false;
> +
> + return (region->free_index >= region->count);
> +}
> +
> +struct vgic_redist_region *vgic_v3_rdist_free_slot(struct list_head *rdregs);
> +
> int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its,
> u32 devid, u32 eventid, struct vgic_irq **irq);
> struct vgic_its *vgic_msi_to_its(struct kvm *kvm, struct kvm_msi *msi);
> --
> 2.5.5
>

Asides from the above:

Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>