[PATCH][SRU Artful] KVM: arm/arm64: vgic-its: Fix return value for device table restore

[Paolo Pisati]

Clean upstream cherry pick.

Acked-by: Paolo Pisati <paolo.pisati at canonical.com>

On Thu, Nov 9, 2017 at 3:19 AM, dann frazier <dann.frazier at canonical.com> wrote:
> From: wanghaibin <wanghaibin.wang at huawei.com>
>
> BugLink: https://bugs.launchpad.net/bugs/1710019
>
> If ITT only contains invalid entries, vgic_its_restore_itt
> returns 1 and this is considered as an an error in
> vgic_its_restore_dte.
>
> Also in case the device table only contains invalid entries,
> the table restore fails and this is not correct.
>
> This patch fixes those 2 issues:
> - vgic_its_restore_itt now returns <= 0 values. If all
>   ITEs are invalid, this is considered as successful.
> - vgic_its_restore_device_tables also returns <= 0 values.
>
> We also simplify the returned value computation in
> handle_l1_dte.
>
> Signed-off-by: wanghaibin <wanghaibin.wang at huawei.com>
> Signed-off-by: Eric Auger <eric.auger at redhat.com>
> Reviewed-by: Christoffer Dall <christoffer.dall at linaro.org>
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
> (cherry picked from commit b92382620e33c9f1bcbcd7c169262b9bf0525871)
> Signed-off-by: dann frazier <dann.frazier at canonical.com>
> ---
>  virt/kvm/arm/vgic/vgic-its.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index aa6b68db80b4..dedf84b858fb 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1942,6 +1942,14 @@ static int vgic_its_save_itt(struct vgic_its *its, struct its_device *device)
>         return 0;
>  }
>
> +/**
> + * vgic_its_restore_itt - restore the ITT of a device
> + *
> + * @its: its handle
> + * @dev: device handle
> + *
> + * Return 0 on success, < 0 on error
> + */
>  static int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
>  {
>         const struct vgic_its_abi *abi = vgic_its_get_abi(its);
> @@ -1953,6 +1961,10 @@ static int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
>         ret = scan_its_table(its, base, max_size, ite_esz, 0,
>                              vgic_its_restore_ite, dev);
>
> +       /* scan_its_table returns +1 if all ITEs are invalid */
> +       if (ret > 0)
> +               ret = 0;
> +
>         return ret;
>  }
>
> @@ -2109,10 +2121,7 @@ static int handle_l1_dte(struct vgic_its *its, u32 id, void *addr,
>         ret = scan_its_table(its, gpa, SZ_64K, dte_esz,
>                              l2_start_id, vgic_its_restore_dte, NULL);
>
> -       if (ret <= 0)
> -               return ret;
> -
> -       return 1;
> +       return ret;
>  }
>
>  /**
> @@ -2142,8 +2151,9 @@ static int vgic_its_restore_device_tables(struct vgic_its *its)
>                                      vgic_its_restore_dte, NULL);
>         }
>
> +       /* scan_its_table returns +1 if all entries are invalid */
>         if (ret > 0)
> -               ret = -EINVAL;
> +               ret = 0;
>
>         return ret;
>  }
> --
> 2.15.0
>
>
> --
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-- 
bye,
p.