Re: [RFC PATCH 3/3] kvm: arm/arm64: vgic-its: fix return value for restore

Auger Eric
2017-09-14T08:28:12Z

Hi Wanghaibin,

On 06/09/2017 15:05, wanghaibin wrote:
> This patch fix the migrate restore tables failure.
>
> The same scene, at the destination, the restore tables interface traversal guest
> memory, and check the dte/ite is valid or not.
> If all dtes/ites are invalid, we will do try next one, and the last it will take
> the 1 return value, but currently, it be treated as error. That's not correct.
>
> This patch try to fix this problem.
>
> Signed-off-by: wanghaibin <wanghaibin.wang@huawei.com>
> ---
> virt/kvm/arm/vgic/vgic-its.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 5c20352..2c69aeb 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -2025,7 +2025,7 @@ static int vgic_its_restore_dte(struct vgic_its *its, u32 id,
> return PTR_ERR(dev);
>
> ret = vgic_its_restore_itt(its, dev);
> - if (ret) {
> + if (ret < 0) {
> vgic_its_free_device(its->dev->kvm, dev);
> return ret;
> }
> @@ -2147,9 +2147,6 @@ static int vgic_its_restore_device_tables(struct vgic_its *its)
> vgic_its_restore_dte, NULL);
> }
>
> - if (ret > 0)
> - ret = -EINVAL;
Reworking error handling in scan_its_table as I previously proposed
indeed don't work for L2 tables, as pointed out by Christoffer. As such
I eventually think your approach is the best.

The only remark I have left is restore table IOCTL is likely to return 1
with your change. 1 is not documented in the API as a returned value. I
think we should return 0 in this case. We are lucky because QEMU
kvm_device_access does not interpret positive values as errors.

Thanks

Eric

> -
> return ret;
> }
>
>