Re: [PATCH 1/2] KVM: arm64: vgic: check redist region is not above the VM IPA size

[Oliver Upton <oupton@google.com>]

Hi Ricardo,

On Wed, Sep 08, 2021 at 02:03:19PM -0700, Ricardo Koller wrote:
> Extend vgic_v3_check_base() to verify that the redistributor regions
> don't go above the VM-specified IPA size (phys_size). This can happen
> when using the legacy KVM_VGIC_V3_ADDR_TYPE_REDIST attribute with:
> 
>   base + size > phys_size AND base < phys_size
> 
> vgic_v3_check_base() is used to check the redist regions bases when
> setting them (with the vcpus added so far) and when attempting the first
> vcpu-run.
> 
> Signed-off-by: Ricardo Koller <ricarkol@google.com>
> ---
>  arch/arm64/kvm/vgic/vgic-v3.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
> index 66004f61cd83..5afd9f6f68f6 100644
> --- a/arch/arm64/kvm/vgic/vgic-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-v3.c
> @@ -512,6 +512,10 @@ bool vgic_v3_check_base(struct kvm *kvm)
>  		if (rdreg->base + vgic_v3_rd_region_size(kvm, rdreg) <
>  			rdreg->base)
>  			return false;

Can we drop this check in favor of explicitly comparing rdreg->base with
kvm_phys_size()? I believe that would be more readable.

> +
> +		if (rdreg->base + vgic_v3_rd_region_size(kvm, rdreg) >
> +			kvm_phys_size(kvm))
> +			return false;
>  	}
>  
>  	if (IS_VGIC_ADDR_UNDEF(d->vgic_dist_base))
> -- 
> 2.33.0.153.gba50c8fa24-goog
> 

--
Thanks,
Oliver