linux-kernel - Re: [PATCH v4 06/12] KVM: arm/arm64: Adapt vgic_v3_check

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Date:   Sun, 29 Apr 2018 14:35:01 +0200
From:   Christoffer Dall <christoffer.dall@....com>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     eric.auger.pro@...il.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
        marc.zyngier@....com, cdall@...nel.org, peter.maydell@...aro.org,
        andre.przywara@....com
Subject: Re: [PATCH v4 06/12] KVM: arm/arm64: Adapt vgic_v3_check_base to
 multiple rdist regions

On Fri, Apr 27, 2018 at 04:14:59PM +0200, Eric Auger wrote:
> vgic_v3_check_base() currently only handles the case of a unique
> legacy redistributor region whose size is not explicitly set but
> infered, instead, from the number of online vcpus.

nit: inferred

> 
> We adapt it to handle the case of multiple redistributor regions
> with explicitly defined size. We rely on two new helpers:
> - vgic_v3_rdist_overlap() is used to detect overlap with the dist
>   region if defined
> - vgic_v3_rd_region_size computes the size of the redist region,
>   would it be a legacy unique region or a new explicitly sized
>   region.
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> 
> ---
> 
> v3 -> v4:
> - squash vgic_v3_check_base adaptation and vgic_v3_rdist_overlap
>   + vgic_v3_rd_region_size introduction  and put this patch
>   before v3 patch 6
> ---
>  virt/kvm/arm/vgic/vgic-v3.c | 49 +++++++++++++++++++++++++++++----------------
>  virt/kvm/arm/vgic/vgic.h    | 10 +++++++++
>  2 files changed, 42 insertions(+), 17 deletions(-)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index f81a63a..c4a2a46 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -410,6 +410,29 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
>  	return 0;
>  }
>  
> +/**
> + * vgic_v3_rdist_overlap - check if a region overlaps with any
> + * existing redistributor region
> + *
> + * @kvm: kvm handle
> + * @base: base of the region
> + * @size: size of region
> + *
> + * Return: true if there is an overlap
> + */
> +bool vgic_v3_rdist_overlap(struct kvm *kvm, gpa_t base, size_t size)
> +{
> +	struct vgic_dist *d = &kvm->arch.vgic;
> +	struct vgic_redist_region *rdreg;
> +
> +	list_for_each_entry(rdreg, &d->rd_regions, list) {
> +		if ((base + size > rdreg->base) &&
> +			(base < rdreg->base + vgic_v3_rd_region_size(kvm, rdreg)))
> +			return true;
> +	}
> +	return false;
> +}
> +
>  /*
>   * Check for overlapping regions and for regions crossing the end of memory
>   * for base addresses which have already been set.
> @@ -417,31 +440,23 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
>  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);
>  }
>  
>  /**
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index fea32cb..e6e3ae9 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -262,6 +262,16 @@ vgic_v3_redist_region_full(struct vgic_redist_region *region)
>  
>  struct vgic_redist_region *vgic_v3_rdist_free_slot(struct list_head *rdregs);
>  
> +static inline size_t
> +vgic_v3_rd_region_size(struct kvm *kvm, struct vgic_redist_region *rdreg)
> +{
> +	if (!rdreg->count)
> +		return atomic_read(&kvm->online_vcpus) * KVM_VGIC_V3_REDIST_SIZE;
> +	else
> +		return rdreg->count * KVM_VGIC_V3_REDIST_SIZE;
> +}
> +bool vgic_v3_rdist_overlap(struct kvm *kvm, gpa_t base, size_t size);
> +
>  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
> 

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