Re: [PATCH v3 07/12] KVM: arm/arm64: Adapt vgic_v3_check_base to multiple rdist regions

Christoffer Dall
2018-04-24T21:07:48Z

On Fri, Apr 13, 2018 at 10:20:53AM +0200, Eric Auger wrote:
> We introduce a new helper to check there is no overlap between
> dist region (if set) and registered rdist regions. This both
> handles the case of legacy single rdist region (implicitly sized
> with the number of online vcpus) and the new case of multiple
> explicitly sized rdist regions.

I don't understand this change, really. Is this just a cleanup, or
changing some functionality (why?).

I think this could have come with the introduction of
vgic_v3_rdist_overlap() before patch 6, and then patch 6 could have been
simplified (hopefully) to just call this "check that nothing in the
world ever collides withi itself" function.

>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> virt/kvm/arm/vgic/vgic-v3.c | 26 +++++++++-----------------
> 1 file changed, 9 insertions(+), 17 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index dbcba5f..b80f650 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -432,31 +432,23 @@ bool vgic_v3_rdist_overlap(struct kvm *kvm, gpa_t base, size_t size)
> bool vgic_v3_check_base(struct kvm *kvm)
> {
> struct vgic_dist *d = &kvm->arch.vgic;
> - gpa_t redist_size = KVM_VGIC_V3_REDIST_SIZE;
> - struct vgic_redist_region *rdreg =
> - list_first_entry(&d->rd_regions,
> - struct vgic_redist_region, list);
> -
> - redist_size *= atomic_read(&kvm->online_vcpus);
> + struct vgic_redist_region *rdreg;
>
> if (!IS_VGIC_ADDR_UNDEF(d->vgic_dist_base) &&
> d->vgic_dist_base + KVM_VGIC_V3_DIST_SIZE < d->vgic_dist_base)
> return false;
>
> - if (rdreg && (rdreg->base + redist_size < rdreg->base))
> - return false;
> + list_for_each_entry(rdreg, &d->rd_regions, list) {
> + if (rdreg->base + vgic_v3_rd_region_size(kvm, rdreg) <
> + rdreg->base)
> + return false;
> + }
>
> - /* Both base addresses must be set to check if they overlap */
> - if (IS_VGIC_ADDR_UNDEF(d->vgic_dist_base) || !rdreg)
> + if (IS_VGIC_ADDR_UNDEF(d->vgic_dist_base))
> return true;
>
> - if (d->vgic_dist_base + KVM_VGIC_V3_DIST_SIZE <= rdreg->base)
> - return true;
> -
> - if (rdreg->base + redist_size <= d->vgic_dist_base)
> - return true;
> -
> - return false;
> + return !vgic_v3_rdist_overlap(kvm, d->vgic_dist_base,
> + KVM_VGIC_V3_DIST_SIZE);
> }
>
> /**
> --
> 2.5.5
>
Otherwise this patch looks correct to me.

Thanks,
-Christoffer