Messages in this thread | | | From | Yongji Xie <> | Date | Wed, 29 Jun 2022 17:02:40 +0800 | Subject | Re: [PATCH 6/6] vduse: Update api version to 1 |
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On Wed, Jun 29, 2022 at 4:33 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > On Wed, Jun 29, 2022 at 04:25:41PM +0800, Xie Yongji wrote: > > Let's update api version to 1 since we introduced > > some new ioctls to support registering userspace > > memory for IOTLB. > > > > Signed-off-by: Xie Yongji <xieyongji@bytedance.com> > > > Adding new ioctls does not justify things like this. >
What I want to do here is make userspace know whether this feature is supported or not in the kernel. So do you think we need to add something like CHECK_EXTENSION ioctl here?
> Besides, adding UAPI then changing it is not nice > since it makes git bisect behave incorrectly. > > > --- > > drivers/vdpa/vdpa_user/vduse_dev.c | 12 ++++++++++++ > > include/uapi/linux/vduse.h | 8 +++++++- > > 2 files changed, 19 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c > > index 7b2ea7612da9..2795785ca6a2 100644 > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > > @@ -1206,6 +1206,10 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd, > > case VDUSE_IOTLB_GET_INFO: { > > struct vduse_iotlb_info iotlb; > > > > + ret = -EPERM; > > > Almost for sure a wrong error code. > > > + if (dev->api_version < 1) > > + break; > > + > > iotlb.bounce_iova = 0; > > iotlb.bounce_size = dev->domain->bounce_size; > > > > > Wait a second. so you are intentionally breaking any userspace > that called VDUSE_SET_API_VERSION with version 0? > > Please don't. >
Yes, I'd like to let userspace know we don't support this feature.
Thanks. Yongji
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