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Message-ID: <20180430094215.GB12204@C02W217FHV2R.local>
Date: Mon, 30 Apr 2018 11:42:15 +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 v5 07/12] KVM: arm/arm64: Helper to register a new
redistributor region
On Mon, Apr 30, 2018 at 11:07:39AM +0200, Eric Auger wrote:
> We introduce a new helper that creates and inserts a new redistributor
> region into the rdist region list. This helper both handles the case
> where the redistributor region size is known at registration time
> and the legacy case where it is not (eventually depending on the number
> of online vcpus). Depending on pfns, we perform all the possible checks
> that we can do:
>
> - end of memory crossing
> - incorrect alignment of the base address
> - collision with distributor region if already defined
> - collision with already registered rdist regions
> - check of the new index
>
> Rdist regions must be inserted by increasing order of indices. Indices
> must be contiguous.
>
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>
> ---
>
> v3 -> v4:
> - inversed check in vgic_v3_rdist_overlap
Which is now in patch 6, but that looks fine to me, so I stand by my
reviewed-by on that patch.
> - use list_last_entry in vgic_v3_insert_redist_region
> - improve comment in vgic_v3_insert_redist_region
> - introduce vgic_dist_overlap
> ---
> virt/kvm/arm/vgic/vgic-mmio-v3.c | 89 ++++++++++++++++++++++++++++++++--------
> virt/kvm/arm/vgic/vgic.h | 8 ++++
> 2 files changed, 81 insertions(+), 16 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index ce5c927..cbf8f4e 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -680,14 +680,63 @@ static int vgic_register_all_redist_iodevs(struct kvm *kvm)
> return ret;
> }
>
> -int vgic_v3_set_redist_base(struct kvm *kvm, u64 addr)
> +/**
> + * vgic_v3_insert_redist_region - Insert a new redistributor region
> + *
> + * Performs various checks before inserting the rdist region in the list.
> + * Those tests depend on whether the size of the rdist region is known
> + * (ie. count != 0). The list is sorted by rdist region index.
> + *
> + * @kvm: kvm handle
> + * @index: redist region index
> + * @base: base of the new rdist region
> + * @count: number of redistributors the region is made of (of 0 in the old style
> + * single region, whose size is induced from the number of vcpus)
> + *
> + * Return 0 on success, < 0 otherwise
> + */
> +static int vgic_v3_insert_redist_region(struct kvm *kvm, uint32_t index,
> + gpa_t base, uint32_t count)
> {
> - struct vgic_dist *vgic = &kvm->arch.vgic;
> + struct vgic_dist *d = &kvm->arch.vgic;
> struct vgic_redist_region *rdreg;
> + struct list_head *rd_regions = &d->rd_regions;
> + struct list_head *last = rd_regions->prev;
> + size_t size = count * KVM_VGIC_V3_REDIST_SIZE;
> int ret;
>
> - /* vgic_check_ioaddr makes sure we don't do this twice */
> - if (!list_empty(&vgic->rd_regions))
> + /* single rdist region already set ?*/
> + if (!count && !list_empty(rd_regions))
> + return -EINVAL;
> +
> + /* cross the end of memory ? */
> + if (base + size < base)
> + return -EINVAL;
> +
> + if (list_empty(rd_regions)) {
> + if (index != 0)
> + return -EINVAL;
> + } else {
> + rdreg = list_entry(last, struct vgic_redist_region, list);
Looks like you may have forgotten to actually change this?
> + if (index != rdreg->index + 1)
> + return -EINVAL;
> +
> + /* Cannot add an explicitly sized regions after legacy region */
> + if (!rdreg->count)
> + return -EINVAL;
> + }
> +
> + /*
> + * For legacy single-region redistributor regions (!count),
> + * check that the redistributor region does not overlap with the
> + * distributor's address space.
> + */
> + if (!count && !IS_VGIC_ADDR_UNDEF(d->vgic_dist_base) &&
> + vgic_dist_overlap(kvm, base, size))
> + return -EINVAL;
> +
> + /* collision with any other rdist region? */
> + if (vgic_v3_rdist_overlap(kvm, base, size))
> return -EINVAL;
>
> rdreg = kzalloc(sizeof(*rdreg), GFP_KERNEL);
> @@ -696,17 +745,29 @@ int vgic_v3_set_redist_base(struct kvm *kvm, u64 addr)
>
> rdreg->base = VGIC_ADDR_UNDEF;
>
> - ret = vgic_check_ioaddr(kvm, &rdreg->base, addr, SZ_64K);
> + ret = vgic_check_ioaddr(kvm, &rdreg->base, base, SZ_64K);
> if (ret)
> - goto out;
> + goto free;
>
> - rdreg->base = addr;
> - if (!vgic_v3_check_base(kvm)) {
> - ret = -EINVAL;
> - goto out;
> - }
> + rdreg->base = base;
> + rdreg->count = count;
> + rdreg->free_index = 0;
> + rdreg->index = index;
>
> - list_add(&rdreg->list, &vgic->rd_regions);
> + list_add_tail(&rdreg->list, rd_regions);
> + return 0;
> +free:
> + kfree(rdreg);
> + return ret;
> +}
> +
> +int vgic_v3_set_redist_base(struct kvm *kvm, u64 addr)
> +{
> + int ret;
> +
> + ret = vgic_v3_insert_redist_region(kvm, 0, addr, 0);
> + if (ret)
> + return ret;
>
> /*
> * Register iodevs for each existing VCPU. Adding more VCPUs
> @@ -717,10 +778,6 @@ int vgic_v3_set_redist_base(struct kvm *kvm, u64 addr)
> return ret;
>
> return 0;
> -
> -out:
> - kfree(rdreg);
> - return ret;
> }
>
> int vgic_v3_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr)
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index e6e3ae9..6af7d8a 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -272,6 +272,14 @@ vgic_v3_rd_region_size(struct kvm *kvm, struct vgic_redist_region *rdreg)
> }
> bool vgic_v3_rdist_overlap(struct kvm *kvm, gpa_t base, size_t size);
>
> +static inline bool vgic_dist_overlap(struct kvm *kvm, gpa_t base, size_t size)
> +{
> + struct vgic_dist *d = &kvm->arch.vgic;
> +
> + return (base + size > d->vgic_dist_base) &&
> + (base < d->vgic_dist_base + KVM_VGIC_V3_DIST_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
>
Besides the nit about using list_last_entry():
Reviewed-by: Christoffer Dall <christoffer.dall@....com>
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