Hi Eric,
On Thu, 01 Apr 2021 09:52:31 +0100,
Eric Auger <eric.auger@xxxxxxxxxx> wrote:
>
> KVM_DEV_ARM_VGIC_GRP_ADDR group doc says we should return
> -EEXIST in case the base address of the redist is already set.
> We currently return -EINVAL.
>
> However we need to return -EINVAL in case a legacy REDIST address
> is attempted to be set while REDIST_REGIONS were set. This case
> is discriminated by looking at the count field.
>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>
> ---
>
> v1 -> v2:
> - simplify the check sequence
> ---
> arch/arm64/kvm/vgic/vgic-mmio-v3.c | 15 +++++++--------
> 1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> index 15a6c98ee92f0..013b737b658f8 100644
> --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> @@ -791,10 +791,6 @@ static int vgic_v3_insert_redist_region(struct kvm *kvm, uint32_t index,
> size_t size = count * KVM_VGIC_V3_REDIST_SIZE;
> int ret;
>
> - /* single rdist region already set ?*/
> - if (!count && !list_empty(rd_regions))
> - return -EINVAL;
> -
> /* cross the end of memory ? */
> if (base + size < base)
> return -EINVAL;
> @@ -805,11 +801,14 @@ static int vgic_v3_insert_redist_region(struct kvm *kvm, uint32_t index,
> } else {
> rdreg = list_last_entry(rd_regions,
> struct vgic_redist_region, list);
> - if (index != rdreg->index + 1)
> - return -EINVAL;
>
> - /* Cannot add an explicitly sized regions after legacy region */
> - if (!rdreg->count)
> + if ((!count) != (!rdreg->count))
> + return -EINVAL; /* Mix REDIST and REDIST_REGION */
Urgh... The triple negation killed me. Can we come up with a more
intuitive expression? Something like:
/* Don't mix single region and discrete redist regions */
if (!count && rdreg->count)
return -EINVAL;
Does it capture what you want to express?
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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