[PATCH v2 3/3] KVM: arm64: vgic-its: Clear ite when discard frees an ite

[Jing Zhang]

Hi Kunkun,

On Thu, Jul 4, 2024 at 7:23 AM Kunkun Jiang <jiangkunkun at huawei.com> wrote:
>
> When discard frees an ite, we do not invalidate the
> corresponding ite. In the scenario of continuous save and
> restore, there may be a situation where an ite is not saved
> but is restored. This is unreasonable and may cause restore
> to fail. This patch clears the corresponding ite when discard
> frees a ite.
nit: ite -> ITE
>
> Signed-off-by: Kunkun Jiang <jiangkunkun at huawei.com>
> ---
>  arch/arm64/kvm/vgic/vgic-its.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
> index 223a5f1d6a3d..cf4a85a29504 100644
> --- a/arch/arm64/kvm/vgic/vgic-its.c
> +++ b/arch/arm64/kvm/vgic/vgic-its.c
> @@ -782,6 +782,10 @@ static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its,
>
>         ite = find_ite(its, device_id, event_id);
>         if (ite && its_is_collection_mapped(ite->collection)) {
> +               struct its_device *device = find_its_device(its, device_id);
> +               int ite_esz = vgic_its_get_abi(its)->ite_esz;
> +               gpa_t gpa = device->itt_addr + ite->event_id * ite_esz;
> +               u64 val = 0;
>                 /*
>                  * Though the spec talks about removing the pending state, we
>                  * don't bother here since we clear the ITTE anyway and the
> @@ -790,6 +794,11 @@ static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its,
>                 vgic_its_invalidate_cache(its);
>
>                 its_free_ite(kvm, ite);
> +
> +               if (KVM_BUG_ON(ite_esz != sizeof(val), kvm))
> +                       return -EINVAL;
> +
> +               vgic_write_guest_lock(kvm, gpa, &val, ite_esz);
>                 return 0;
>         }
>
> --
> 2.27.0
>
>

Jing