On Mon, Oct 23 2017 at 4:08:22 pm BST, Eric Auger <eric.auger@xxxxxxxxxx> wrote:
> The spec says it is UNPREDICTABLE to enable the ITS
> if any of the following conditions are true:
>
> - GITS_CBASER.Valid == 0.
> - GITS_BASER<n>.Valid == 0, for any GITS_BASER<n> register
> where the Type field indicates Device.
> - GITS_BASER<n>.Valid == 0, for any GITS_BASER<n> register
> where the Type field indicates Interrupt Collection and
> GITS_TYPER.HCC == 0.
>
> In that case, let's keep the ITS disabled.
>
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
> Reported-by: Andre Przywara <andre.przywara@xxxxxxx>
>
> ---
>
> need to be CC'ed stable
>
> v4 -> v5:
> - check the condition before updating its->enabled and
> fix its->cbaser && GITS_CBASER_VALID
>
> v3: creation
> ---
> virt/kvm/arm/vgic/vgic-its.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index b0ba80f..1eb355e 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1466,6 +1466,16 @@ static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
> {
> mutex_lock(&its->cmd_lock);
>
> + /*
> + * It is UNPREDICTABLE to enable the ITS if any of the CBASER or
> + * device/collection BASER are invalid
> + */
> + if (!its->enabled && (val & GITS_CTLR_ENABLE) &&
> + (!(its->baser_device_table & GITS_BASER_VALID) ||
> + !(its->baser_coll_table & GITS_BASER_VALID) ||
> + !(its->cbaser & GITS_CBASER_VALID)))
> + goto out;
> +
> its->enabled = !!(val & GITS_CTLR_ENABLE);
>
> /*
> @@ -1474,6 +1484,7 @@ static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
> */
> vgic_its_process_commands(kvm, its);
>
> +out:
> mutex_unlock(&its->cmd_lock);
> }
While this is definitely a good hardening of the implementation, I don't
think it fixes anything for the guest which is already misbehaving and
would just not get anything out of this misconfigurarion (in line with
the UNPRED requirement).
So I don't think we need to Cc stable for this. Otherwise:
Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>
M.
--
Jazz is not dead. It just smells funny.
