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[PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER

Cindy Lu posted 8 patches 11 months, 2 weeks ago
There is a newer version of this series
[PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Cindy Lu 11 months, 2 weeks ago 
Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
is disabled, and any attempt to use it will result in failure.

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
 drivers/vhost/Kconfig | 15 +++++++++++++++
 drivers/vhost/vhost.c | 11 +++++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index b455d9ab6f3d..e5b9dcbf31b6 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
 	  If unsure, say "N".
 
 endif
+
+config VHOST_ENABLE_FORK_OWNER_IOCTL
+	bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
+	default n
+	help
+	  This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
+	  userspace applications to modify the thread mode for vhost devices.
+
+          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
+          meaning the ioctl is disabled and any operation using this ioctl
+          will fail.
+          When the configuration is enabled (y), the ioctl becomes
+          available, allowing users to set the mode if needed.
+
+	  If unsure, say "N".
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index fb0c7fb43f78..09e5e44dc516 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
 		r = vhost_dev_set_owner(d);
 		goto done;
 	}
+
+#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
 	if (ioctl == VHOST_FORK_FROM_OWNER) {
 		u8 inherit_owner;
 		/*inherit_owner can only be modified before owner is set*/
@@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
 		r = 0;
 		goto done;
 	}
+
+#else
+	if (ioctl == VHOST_FORK_FROM_OWNER) {
+		/* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
+		r = -ENOTTY;
+		goto done;
+	}
+#endif
+
 	/* You must be the owner to do anything else */
 	r = vhost_dev_check_owner(d);
 	if (r)
-- 
2.45.0
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Jason Wang 11 months, 2 weeks ago 
On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
>
> Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
> to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
> When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
> is disabled, and any attempt to use it will result in failure.
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>  drivers/vhost/Kconfig | 15 +++++++++++++++
>  drivers/vhost/vhost.c | 11 +++++++++++
>  2 files changed, 26 insertions(+)
>
> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> index b455d9ab6f3d..e5b9dcbf31b6 100644
> --- a/drivers/vhost/Kconfig
> +++ b/drivers/vhost/Kconfig
> @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
>           If unsure, say "N".
>
>  endif
> +
> +config VHOST_ENABLE_FORK_OWNER_IOCTL
> +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
> +       default n
> +       help
> +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
> +         userspace applications to modify the thread mode for vhost devices.
> +
> +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
> +          meaning the ioctl is disabled and any operation using this ioctl
> +          will fail.
> +          When the configuration is enabled (y), the ioctl becomes
> +          available, allowing users to set the mode if needed.
> +
> +         If unsure, say "N".
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index fb0c7fb43f78..09e5e44dc516 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
>                 r = vhost_dev_set_owner(d);
>                 goto done;
>         }
> +
> +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
>         if (ioctl == VHOST_FORK_FROM_OWNER) {
>                 u8 inherit_owner;
>                 /*inherit_owner can only be modified before owner is set*/
> @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
>                 r = 0;
>                 goto done;
>         }
> +
> +#else
> +       if (ioctl == VHOST_FORK_FROM_OWNER) {
> +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
> +               r = -ENOTTY;
> +               goto done;
> +       }
> +#endif
> +
>         /* You must be the owner to do anything else */
>         r = vhost_dev_check_owner(d);
>         if (r)
> --
> 2.45.0

Do we need to change the default value of the inhert_owner? For example:

#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
inherit_owner = false;
#else
inherit_onwer = true;
#endif

?

Other patches look good to me.

Thanks

>
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Michael S. Tsirkin 10 months, 3 weeks ago 
On Mon, Mar 03, 2025 at 01:52:06PM +0800, Jason Wang wrote:
> On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
> >
> > Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
> > to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
> > When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
> > is disabled, and any attempt to use it will result in failure.
> >
> > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > ---
> >  drivers/vhost/Kconfig | 15 +++++++++++++++
> >  drivers/vhost/vhost.c | 11 +++++++++++
> >  2 files changed, 26 insertions(+)
> >
> > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> > index b455d9ab6f3d..e5b9dcbf31b6 100644
> > --- a/drivers/vhost/Kconfig
> > +++ b/drivers/vhost/Kconfig
> > @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
> >           If unsure, say "N".
> >
> >  endif
> > +
> > +config VHOST_ENABLE_FORK_OWNER_IOCTL
> > +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
> > +       default n
> > +       help
> > +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
> > +         userspace applications to modify the thread mode for vhost devices.
> > +
> > +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
> > +          meaning the ioctl is disabled and any operation using this ioctl
> > +          will fail.
> > +          When the configuration is enabled (y), the ioctl becomes
> > +          available, allowing users to set the mode if needed.
> > +
> > +         If unsure, say "N".
> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > index fb0c7fb43f78..09e5e44dc516 100644
> > --- a/drivers/vhost/vhost.c
> > +++ b/drivers/vhost/vhost.c
> > @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> >                 r = vhost_dev_set_owner(d);
> >                 goto done;
> >         }
> > +
> > +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> >         if (ioctl == VHOST_FORK_FROM_OWNER) {
> >                 u8 inherit_owner;
> >                 /*inherit_owner can only be modified before owner is set*/
> > @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> >                 r = 0;
> >                 goto done;
> >         }
> > +
> > +#else
> > +       if (ioctl == VHOST_FORK_FROM_OWNER) {
> > +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
> > +               r = -ENOTTY;
> > +               goto done;
> > +       }
> > +#endif
> > +
> >         /* You must be the owner to do anything else */
> >         r = vhost_dev_check_owner(d);
> >         if (r)
> > --
> > 2.45.0
> 
> Do we need to change the default value of the inhert_owner? For example:
> 
> #ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> inherit_owner = false;
> #else
> inherit_onwer = true;
> #endif
> 
> ?
> 
> Other patches look good to me.
> 
> Thanks


I think I agree with Cindy. kconfig just tells us whether the
ioctl is allowed. should not affect the default, if we want
a kconfig for default, it should be separate, but I doubt it.

> >
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Michael S. Tsirkin 11 months, 2 weeks ago 
On Mon, Mar 03, 2025 at 01:52:06PM +0800, Jason Wang wrote:
> On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
> >
> > Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
> > to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
> > When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
> > is disabled, and any attempt to use it will result in failure.
> >
> > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > ---
> >  drivers/vhost/Kconfig | 15 +++++++++++++++
> >  drivers/vhost/vhost.c | 11 +++++++++++
> >  2 files changed, 26 insertions(+)
> >
> > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> > index b455d9ab6f3d..e5b9dcbf31b6 100644
> > --- a/drivers/vhost/Kconfig
> > +++ b/drivers/vhost/Kconfig
> > @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
> >           If unsure, say "N".
> >
> >  endif
> > +
> > +config VHOST_ENABLE_FORK_OWNER_IOCTL
> > +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
> > +       default n
> > +       help
> > +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
> > +         userspace applications to modify the thread mode for vhost devices.
> > +
> > +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
> > +          meaning the ioctl is disabled and any operation using this ioctl
> > +          will fail.
> > +          When the configuration is enabled (y), the ioctl becomes
> > +          available, allowing users to set the mode if needed.
> > +
> > +         If unsure, say "N".
> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > index fb0c7fb43f78..09e5e44dc516 100644
> > --- a/drivers/vhost/vhost.c
> > +++ b/drivers/vhost/vhost.c
> > @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> >                 r = vhost_dev_set_owner(d);
> >                 goto done;
> >         }
> > +
> > +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> >         if (ioctl == VHOST_FORK_FROM_OWNER) {
> >                 u8 inherit_owner;
> >                 /*inherit_owner can only be modified before owner is set*/
> > @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> >                 r = 0;
> >                 goto done;
> >         }
> > +
> > +#else
> > +       if (ioctl == VHOST_FORK_FROM_OWNER) {
> > +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
> > +               r = -ENOTTY;
> > +               goto done;
> > +       }

why do we need this? won't it fail as any other unsupported ioctl?

> > +#endif
> > +
> >         /* You must be the owner to do anything else */
> >         r = vhost_dev_check_owner(d);
> >         if (r)
> > --
> > 2.45.0
> 
> Do we need to change the default value of the inhert_owner? For example:
> 
> #ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> inherit_owner = false;
> #else
> inherit_onwer = true;
> #endif
> 
> ?

I feel it is best to keep the default consistent.
All the kconfig should do, is block the ioctl.


> Other patches look good to me.
> 
> Thanks
> 
> >
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Cindy Lu 10 months, 2 weeks ago 
On Tue, Mar 4, 2025 at 1:33 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Mar 03, 2025 at 01:52:06PM +0800, Jason Wang wrote:
> > On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
> > >
> > > Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
> > > to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
> > > When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
> > > is disabled, and any attempt to use it will result in failure.
> > >
> > > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > > ---
> > >  drivers/vhost/Kconfig | 15 +++++++++++++++
> > >  drivers/vhost/vhost.c | 11 +++++++++++
> > >  2 files changed, 26 insertions(+)
> > >
> > > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> > > index b455d9ab6f3d..e5b9dcbf31b6 100644
> > > --- a/drivers/vhost/Kconfig
> > > +++ b/drivers/vhost/Kconfig
> > > @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
> > >           If unsure, say "N".
> > >
> > >  endif
> > > +
> > > +config VHOST_ENABLE_FORK_OWNER_IOCTL
> > > +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
> > > +       default n
> > > +       help
> > > +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
> > > +         userspace applications to modify the thread mode for vhost devices.
> > > +
> > > +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
> > > +          meaning the ioctl is disabled and any operation using this ioctl
> > > +          will fail.
> > > +          When the configuration is enabled (y), the ioctl becomes
> > > +          available, allowing users to set the mode if needed.
> > > +
> > > +         If unsure, say "N".
> > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > > index fb0c7fb43f78..09e5e44dc516 100644
> > > --- a/drivers/vhost/vhost.c
> > > +++ b/drivers/vhost/vhost.c
> > > @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> > >                 r = vhost_dev_set_owner(d);
> > >                 goto done;
> > >         }
> > > +
> > > +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> > >         if (ioctl == VHOST_FORK_FROM_OWNER) {
> > >                 u8 inherit_owner;
> > >                 /*inherit_owner can only be modified before owner is set*/
> > > @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> > >                 r = 0;
> > >                 goto done;
> > >         }
> > > +
> > > +#else
> > > +       if (ioctl == VHOST_FORK_FROM_OWNER) {
> > > +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
> > > +               r = -ENOTTY;
> > > +               goto done;
> > > +       }
>
> why do we need this? won't it fail as any other unsupported ioctl?
>
Sure, will remove  this
thanks
cindy
> > > +#endif
> > > +
> > >         /* You must be the owner to do anything else */
> > >         r = vhost_dev_check_owner(d);
> > >         if (r)
> > > --
> > > 2.45.0
> >
> > Do we need to change the default value of the inhert_owner? For example:
> >
> > #ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> > inherit_owner = false;
> > #else
> > inherit_onwer = true;
> > #endif
> >
> > ?
>
> I feel it is best to keep the default consistent.
> All the kconfig should do, is block the ioctl.
>
>
> > Other patches look good to me.
> >
> > Thanks
> >
> > >
>
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Jason Wang 11 months, 1 week ago 
On Tue, Mar 4, 2025 at 1:33 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Mar 03, 2025 at 01:52:06PM +0800, Jason Wang wrote:
> > On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
> > >
> > > Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
> > > to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
> > > When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
> > > is disabled, and any attempt to use it will result in failure.
> > >
> > > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > > ---
> > >  drivers/vhost/Kconfig | 15 +++++++++++++++
> > >  drivers/vhost/vhost.c | 11 +++++++++++
> > >  2 files changed, 26 insertions(+)
> > >
> > > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> > > index b455d9ab6f3d..e5b9dcbf31b6 100644
> > > --- a/drivers/vhost/Kconfig
> > > +++ b/drivers/vhost/Kconfig
> > > @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
> > >           If unsure, say "N".
> > >
> > >  endif
> > > +
> > > +config VHOST_ENABLE_FORK_OWNER_IOCTL
> > > +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
> > > +       default n
> > > +       help
> > > +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
> > > +         userspace applications to modify the thread mode for vhost devices.
> > > +
> > > +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
> > > +          meaning the ioctl is disabled and any operation using this ioctl
> > > +          will fail.
> > > +          When the configuration is enabled (y), the ioctl becomes
> > > +          available, allowing users to set the mode if needed.
> > > +
> > > +         If unsure, say "N".
> > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > > index fb0c7fb43f78..09e5e44dc516 100644
> > > --- a/drivers/vhost/vhost.c
> > > +++ b/drivers/vhost/vhost.c
> > > @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> > >                 r = vhost_dev_set_owner(d);
> > >                 goto done;
> > >         }
> > > +
> > > +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> > >         if (ioctl == VHOST_FORK_FROM_OWNER) {
> > >                 u8 inherit_owner;
> > >                 /*inherit_owner can only be modified before owner is set*/
> > > @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> > >                 r = 0;
> > >                 goto done;
> > >         }
> > > +
> > > +#else
> > > +       if (ioctl == VHOST_FORK_FROM_OWNER) {
> > > +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
> > > +               r = -ENOTTY;
> > > +               goto done;
> > > +       }
>
> why do we need this? won't it fail as any other unsupported ioctl?
>
> > > +#endif
> > > +
> > >         /* You must be the owner to do anything else */
> > >         r = vhost_dev_check_owner(d);
> > >         if (r)
> > > --
> > > 2.45.0
> >
> > Do we need to change the default value of the inhert_owner? For example:
> >
> > #ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> > inherit_owner = false;
> > #else
> > inherit_onwer = true;
> > #endif
> >
> > ?
>
> I feel it is best to keep the default consistent.

Just want to make sure we are on the same page.

For "default", did you mean inherit_owner = false which is consistent
with behaviour without the vhost task?

Or inherit_onwer = true, then the new ioctl to make it false is
useless. And if legacy applications want kthread behaviour it needs to
be patched which seems self-contradictory.

> All the kconfig should do, is block the ioctl.
>

Thanks

>
> > Other patches look good to me.
> >
> > Thanks
> >
> > >
>
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Cindy Lu 10 months, 3 weeks ago 
Ping :)

On Mon, Mar 10, 2025 at 12:54 PM Jason Wang <jasowang@redhat.com> wrote:
>
> On Tue, Mar 4, 2025 at 1:33 AM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Mon, Mar 03, 2025 at 01:52:06PM +0800, Jason Wang wrote:
> > > On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
> > > >
> > > > Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
> > > > to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
> > > > When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
> > > > is disabled, and any attempt to use it will result in failure.
> > > >
> > > > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > > > ---
> > > >  drivers/vhost/Kconfig | 15 +++++++++++++++
> > > >  drivers/vhost/vhost.c | 11 +++++++++++
> > > >  2 files changed, 26 insertions(+)
> > > >
> > > > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> > > > index b455d9ab6f3d..e5b9dcbf31b6 100644
> > > > --- a/drivers/vhost/Kconfig
> > > > +++ b/drivers/vhost/Kconfig
> > > > @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
> > > >           If unsure, say "N".
> > > >
> > > >  endif
> > > > +
> > > > +config VHOST_ENABLE_FORK_OWNER_IOCTL
> > > > +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
> > > > +       default n
> > > > +       help
> > > > +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
> > > > +         userspace applications to modify the thread mode for vhost devices.
> > > > +
> > > > +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
> > > > +          meaning the ioctl is disabled and any operation using this ioctl
> > > > +          will fail.
> > > > +          When the configuration is enabled (y), the ioctl becomes
> > > > +          available, allowing users to set the mode if needed.
> > > > +
> > > > +         If unsure, say "N".
> > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > > > index fb0c7fb43f78..09e5e44dc516 100644
> > > > --- a/drivers/vhost/vhost.c
> > > > +++ b/drivers/vhost/vhost.c
> > > > @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> > > >                 r = vhost_dev_set_owner(d);
> > > >                 goto done;
> > > >         }
> > > > +
> > > > +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> > > >         if (ioctl == VHOST_FORK_FROM_OWNER) {
> > > >                 u8 inherit_owner;
> > > >                 /*inherit_owner can only be modified before owner is set*/
> > > > @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> > > >                 r = 0;
> > > >                 goto done;
> > > >         }
> > > > +
> > > > +#else
> > > > +       if (ioctl == VHOST_FORK_FROM_OWNER) {
> > > > +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
> > > > +               r = -ENOTTY;
> > > > +               goto done;
> > > > +       }
> >
> > why do we need this? won't it fail as any other unsupported ioctl?
> >
> > > > +#endif
> > > > +
> > > >         /* You must be the owner to do anything else */
> > > >         r = vhost_dev_check_owner(d);
> > > >         if (r)
> > > > --
> > > > 2.45.0
> > >
> > > Do we need to change the default value of the inhert_owner? For example:
> > >
> > > #ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> > > inherit_owner = false;
> > > #else
> > > inherit_onwer = true;
> > > #endif
> > >
> > > ?
> >
> > I feel it is best to keep the default consistent.
>
> Just want to make sure we are on the same page.
>
> For "default", did you mean inherit_owner = false which is consistent
> with behaviour without the vhost task?
>
> Or inherit_onwer = true, then the new ioctl to make it false is
> useless. And if legacy applications want kthread behaviour it needs to
> be patched which seems self-contradictory.
>
> > All the kconfig should do, is block the ioctl.
> >
>
> Thanks
>
> >
> > > Other patches look good to me.
> > >
> > > Thanks
> > >
> > > >
> >
>
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Stefano Garzarella 11 months, 2 weeks ago 
On Mon, Mar 03, 2025 at 01:52:06PM +0800, Jason Wang wrote:
>On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
>>
>> Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
>> to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
>> When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
>> is disabled, and any attempt to use it will result in failure.
>>
>> Signed-off-by: Cindy Lu <lulu@redhat.com>
>> ---
>>  drivers/vhost/Kconfig | 15 +++++++++++++++
>>  drivers/vhost/vhost.c | 11 +++++++++++
>>  2 files changed, 26 insertions(+)
>>
>> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
>> index b455d9ab6f3d..e5b9dcbf31b6 100644
>> --- a/drivers/vhost/Kconfig
>> +++ b/drivers/vhost/Kconfig
>> @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
>>           If unsure, say "N".
>>
>>  endif
>> +
>> +config VHOST_ENABLE_FORK_OWNER_IOCTL
>> +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
>> +       default n
>> +       help
>> +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
>> +         userspace applications to modify the thread mode for vhost devices.
>> +
>> +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
>> +          meaning the ioctl is disabled and any operation using this ioctl
>> +          will fail.
>> +          When the configuration is enabled (y), the ioctl becomes
>> +          available, allowing users to set the mode if needed.
>> +
>> +         If unsure, say "N".
>> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>> index fb0c7fb43f78..09e5e44dc516 100644
>> --- a/drivers/vhost/vhost.c
>> +++ b/drivers/vhost/vhost.c
>> @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
>>                 r = vhost_dev_set_owner(d);
>>                 goto done;
>>         }
>> +
>> +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
>>         if (ioctl == VHOST_FORK_FROM_OWNER) {
>>                 u8 inherit_owner;
>>                 /*inherit_owner can only be modified before owner is set*/
>> @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
>>                 r = 0;
>>                 goto done;
>>         }
>> +

nit: this empyt line is not needed

>> +#else
>> +       if (ioctl == VHOST_FORK_FROM_OWNER) {
>> +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
>> +               r = -ENOTTY;
>> +               goto done;
>> +       }
>> +#endif
>> +
>>         /* You must be the owner to do anything else */
>>         r = vhost_dev_check_owner(d);
>>         if (r)
>> --
>> 2.45.0
>
>Do we need to change the default value of the inhert_owner? For example:
>
>#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
>inherit_owner = false;
>#else
>inherit_onwer = true;
>#endif
>
>?

I'm not sure about this honestly, the user space has no way to figure 
out the default value and still has to do the IOCTL.
So IMHO better to have a default value that is independent of the kernel 
configuration and consistent with the current behavior.

Thanks,
Stefano

>
>Other patches look good to me.
>
>Thanks
>
>>
>
Re: [PATCH v7 8/8] vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
Posted by Cindy Lu 10 months, 2 weeks ago 
On Mon, Mar 3, 2025 at 5:12 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> On Mon, Mar 03, 2025 at 01:52:06PM +0800, Jason Wang wrote:
> >On Sun, Mar 2, 2025 at 10:34 PM Cindy Lu <lulu@redhat.com> wrote:
> >>
> >> Introduce a new config knob `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL`,
> >> to control the availability of the `VHOST_FORK_FROM_OWNER` ioctl.
> >> When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is set to n, the ioctl
> >> is disabled, and any attempt to use it will result in failure.
> >>
> >> Signed-off-by: Cindy Lu <lulu@redhat.com>
> >> ---
> >>  drivers/vhost/Kconfig | 15 +++++++++++++++
> >>  drivers/vhost/vhost.c | 11 +++++++++++
> >>  2 files changed, 26 insertions(+)
> >>
> >> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> >> index b455d9ab6f3d..e5b9dcbf31b6 100644
> >> --- a/drivers/vhost/Kconfig
> >> +++ b/drivers/vhost/Kconfig
> >> @@ -95,3 +95,18 @@ config VHOST_CROSS_ENDIAN_LEGACY
> >>           If unsure, say "N".
> >>
> >>  endif
> >> +
> >> +config VHOST_ENABLE_FORK_OWNER_IOCTL
> >> +       bool "Enable IOCTL VHOST_FORK_FROM_OWNER"
> >> +       default n
> >> +       help
> >> +         This option enables the IOCTL VHOST_FORK_FROM_OWNER, which allows
> >> +         userspace applications to modify the thread mode for vhost devices.
> >> +
> >> +          By default, `CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL` is set to `n`,
> >> +          meaning the ioctl is disabled and any operation using this ioctl
> >> +          will fail.
> >> +          When the configuration is enabled (y), the ioctl becomes
> >> +          available, allowing users to set the mode if needed.
> >> +
> >> +         If unsure, say "N".
> >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> >> index fb0c7fb43f78..09e5e44dc516 100644
> >> --- a/drivers/vhost/vhost.c
> >> +++ b/drivers/vhost/vhost.c
> >> @@ -2294,6 +2294,8 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> >>                 r = vhost_dev_set_owner(d);
> >>                 goto done;
> >>         }
> >> +
> >> +#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> >>         if (ioctl == VHOST_FORK_FROM_OWNER) {
> >>                 u8 inherit_owner;
> >>                 /*inherit_owner can only be modified before owner is set*/
> >> @@ -2313,6 +2315,15 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> >>                 r = 0;
> >>                 goto done;
> >>         }
> >> +
>
> nit: this empyt line is not needed
>
sure , will fix this
Thanks
Cindy
> >> +#else
> >> +       if (ioctl == VHOST_FORK_FROM_OWNER) {
> >> +               /* When CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL is 'n', return error */
> >> +               r = -ENOTTY;
> >> +               goto done;
> >> +       }
> >> +#endif
> >> +
> >>         /* You must be the owner to do anything else */
> >>         r = vhost_dev_check_owner(d);
> >>         if (r)
> >> --
> >> 2.45.0
> >
> >Do we need to change the default value of the inhert_owner? For example:
> >
> >#ifdef CONFIG_VHOST_ENABLE_FORK_OWNER_IOCTL
> >inherit_owner = false;
> >#else
> >inherit_onwer = true;
> >#endif
> >
> >?
>
> I'm not sure about this honestly, the user space has no way to figure
> out the default value and still has to do the IOCTL.
> So IMHO better to have a default value that is independent of the kernel
> configuration and consistent with the current behavior.
>
> Thanks,
> Stefano
>
> >
> >Other patches look good to me.
> >
> >Thanks
> >
> >>
> >
>

Patchew 2.1-devel-b67e4c2

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