Hi Eric,

On 12/12/20 6:50 PM, Eric Auger 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 <[email protected]>
> ---
>  arch/arm64/kvm/vgic/vgic-mmio-v3.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c 
> b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> index 15a6c98ee92f..8e8a862def76 100644
> --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> @@ -792,8 +792,13 @@ static int vgic_v3_insert_redist_region(struct kvm *kvm, 
> uint32_t index,
>       int ret;
>  
>       /* single rdist region already set ?*/
> -     if (!count && !list_empty(rd_regions))
> -             return -EINVAL;
> +     if (!count && !list_empty(rd_regions)) {
> +             rdreg = list_last_entry(rd_regions,
> +                                    struct vgic_redist_region, list);
> +             if (rdreg->count)
> +                     return -EINVAL; /* Mixing REDIST and REDIST_REGION API 
> */
> +             return -EEXIST;
> +     }

A few instructions below:

    if (list_empty(rd_regions)) {
        [..]
    } else {
        rdreg = list_last_entry(rd_regions,
                    struct vgic_redist_region, list);
        [..]

        /* Cannot add an explicitly sized regions after legacy region */
        if (!rdreg->count)
            return -EINVAL;
    }

Isn't this testing for the same thing, but using the opposite condition? Or am I
misunderstanding the code (quite likely)?

Looks to me like 
KVM_DEV_ARM_VGIC_GRP_ADDR(KVM_VGIC_V3_ADDR_TYPE_REDIST{,_REGION})
used to return -EEXIST (from vgic_check_ioaddr()) before commit ccc27bf5be7b7
("KVM: arm/arm64: Helper to register a new redistributor region") which added 
the
vgic_v3_insert_redist_region() function, so bringing back the -EEXIST return 
code
looks the right thing to me.

Thanks,
Alex
>  
>       /* cross the end of memory ? */
>       if (base + size < base)
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