Add an explicit MODULE_VERSION("0.0.1") specification
for a vhost_vsock module. It is useful because it allows
userspace to check if vhost_vsock is there when it is
configured as a built-in.

Without this change, there is no /sys/module/vhost_vsock directory.

With this change:
$ ls -la /sys/module/vhost_vsock/
total 0
drwxr-xr-x   2 root root    0 Sep 26 15:59 .
drwxr-xr-x 100 root root    0 Sep 26 15:59 ..
--w-------   1 root root 4096 Sep 26 15:59 uevent
-r--r--r--   1 root root 4096 Sep 26 15:59 version

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
---
 drivers/vhost/vsock.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 802153e23073..287ea8e480b5 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -956,6 +956,7 @@ static void __exit vhost_vsock_exit(void)
 
 module_init(vhost_vsock_init);
 module_exit(vhost_vsock_exit);
+MODULE_VERSION("0.0.1");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Asias He");
 MODULE_DESCRIPTION("vhost transport for vsock ");
-- 
2.34.1

On Thu, Sep 26, 2024 at 06:16:40PM +0200, Alexander Mikhalitsyn wrote:
> Add an explicit MODULE_VERSION("0.0.1") specification
> for a vhost_vsock module. It is useful because it allows
> userspace to check if vhost_vsock is there when it is
> configured as a built-in.
> 
> Without this change, there is no /sys/module/vhost_vsock directory.
> 
> With this change:
> $ ls -la /sys/module/vhost_vsock/
> total 0
> drwxr-xr-x   2 root root    0 Sep 26 15:59 .
> drwxr-xr-x 100 root root    0 Sep 26 15:59 ..
> --w-------   1 root root 4096 Sep 26 15:59 uevent
> -r--r--r--   1 root root 4096 Sep 26 15:59 version
> 
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>


Why not check that the misc device is registered?
I'd rather not add a new UAPI until actually necessary.

> ---
>  drivers/vhost/vsock.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 802153e23073..287ea8e480b5 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -956,6 +956,7 @@ static void __exit vhost_vsock_exit(void)
>  
>  module_init(vhost_vsock_init);
>  module_exit(vhost_vsock_exit);
> +MODULE_VERSION("0.0.1");
>  MODULE_LICENSE("GPL v2");
>  MODULE_AUTHOR("Asias He");
>  MODULE_DESCRIPTION("vhost transport for vsock ");
> -- 
> 2.34.1

On Sun, Sep 29, 2024 at 6:56 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Thu, Sep 26, 2024 at 06:16:40PM +0200, Alexander Mikhalitsyn wrote:
> > Add an explicit MODULE_VERSION("0.0.1") specification
> > for a vhost_vsock module. It is useful because it allows
> > userspace to check if vhost_vsock is there when it is
> > configured as a built-in.
> >
> > Without this change, there is no /sys/module/vhost_vsock directory.
> >
> > With this change:
> > $ ls -la /sys/module/vhost_vsock/
> > total 0
> > drwxr-xr-x   2 root root    0 Sep 26 15:59 .
> > drwxr-xr-x 100 root root    0 Sep 26 15:59 ..
> > --w-------   1 root root 4096 Sep 26 15:59 uevent
> > -r--r--r--   1 root root 4096 Sep 26 15:59 version
> >
> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
>
>

Dear Michael,

> Why not check that the misc device is registered?

It is possible to read /proc/misc and check if "241 vhost-vsock" is
there, but it means that userspace
needs to have a specific logic for vsock. At the same time, it's quite
convenient to do something like:
    if [ ! -d /sys/modules/vhost_vsock ]; then
        modprobe vhost_vsock
    fi

> I'd rather not add a new UAPI until actually necessary.

I don't insist. I decided to send this patch because, while I was
debugging a non-related kernel issue
on my local dev environment I accidentally discovered that LXD
(containers and VM manager)
fails to run VMs because it fails to load the vhost_vsock module (but
it was built-in in my debug kernel
and the module file didn't exist). Then I discovered that before
trying to load a module we
check if /sys/module/<module name> exists. And found that, for some
reason /sys/module/vhost_vsock
does not exist when vhost_vsock is configured as a built-in, and
/sys/module/vhost_vsock *does* exist when
vhost_vsock is loaded as a module. It looks like an inconsistency and
I also checked that other modules in
drivers/vhost have MODULE_VERSION specified and version is 0.0.1. I
thought that this change looks legitimate
and convenient for userspace consumers.

Kind regards,
Alex

>
> > ---
> >  drivers/vhost/vsock.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > index 802153e23073..287ea8e480b5 100644
> > --- a/drivers/vhost/vsock.c
> > +++ b/drivers/vhost/vsock.c
> > @@ -956,6 +956,7 @@ static void __exit vhost_vsock_exit(void)
> >
> >  module_init(vhost_vsock_init);
> >  module_exit(vhost_vsock_exit);
> > +MODULE_VERSION("0.0.1");
> >  MODULE_LICENSE("GPL v2");
> >  MODULE_AUTHOR("Asias He");
> >  MODULE_DESCRIPTION("vhost transport for vsock ");
> > --
> > 2.34.1
>

On Sun, Sep 29, 2024 at 07:35:35PM +0200, Aleksandr Mikhalitsyn wrote:
> On Sun, Sep 29, 2024 at 6:56 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Thu, Sep 26, 2024 at 06:16:40PM +0200, Alexander Mikhalitsyn wrote:
> > > Add an explicit MODULE_VERSION("0.0.1") specification
> > > for a vhost_vsock module. It is useful because it allows
> > > userspace to check if vhost_vsock is there when it is
> > > configured as a built-in.
> > >
> > > Without this change, there is no /sys/module/vhost_vsock directory.
> > >
> > > With this change:
> > > $ ls -la /sys/module/vhost_vsock/
> > > total 0
> > > drwxr-xr-x   2 root root    0 Sep 26 15:59 .
> > > drwxr-xr-x 100 root root    0 Sep 26 15:59 ..
> > > --w-------   1 root root 4096 Sep 26 15:59 uevent
> > > -r--r--r--   1 root root 4096 Sep 26 15:59 version
> > >
> > > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> >
> >
> 
> Dear Michael,
> 
> > Why not check that the misc device is registered?
> 
> It is possible to read /proc/misc and check if "241 vhost-vsock" is
> there, but it means that userspace
> needs to have a specific logic for vsock. At the same time, it's quite
> convenient to do something like:
>     if [ ! -d /sys/modules/vhost_vsock ]; then
>         modprobe vhost_vsock
>     fi
> 
> > I'd rather not add a new UAPI until actually necessary.
> 
> I don't insist. I decided to send this patch because, while I was
> debugging a non-related kernel issue
> on my local dev environment I accidentally discovered that LXD
> (containers and VM manager)
> fails to run VMs because it fails to load the vhost_vsock module (but
> it was built-in in my debug kernel
> and the module file didn't exist). Then I discovered that before
> trying to load a module we
> check if /sys/module/<module name> exists. And found that, for some
> reason /sys/module/vhost_vsock
> does not exist when vhost_vsock is configured as a built-in, and
> /sys/module/vhost_vsock *does* exist when
> vhost_vsock is loaded as a module. It looks like an inconsistency and
> I also checked that other modules in
> drivers/vhost have MODULE_VERSION specified and version is 0.0.1. I
> thought that this change looks legitimate
> and convenient for userspace consumers.
> 
> Kind regards,
> Alex

Aha, that's a different matter.
Given userspace already depends on this UAPI, it's easier
to fix it in the kernel.


> >
> > > ---
> > >  drivers/vhost/vsock.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > > index 802153e23073..287ea8e480b5 100644
> > > --- a/drivers/vhost/vsock.c
> > > +++ b/drivers/vhost/vsock.c
> > > @@ -956,6 +956,7 @@ static void __exit vhost_vsock_exit(void)
> > >
> > >  module_init(vhost_vsock_init);
> > >  module_exit(vhost_vsock_exit);
> > > +MODULE_VERSION("0.0.1");
> > >  MODULE_LICENSE("GPL v2");
> > >  MODULE_AUTHOR("Asias He");
> > >  MODULE_DESCRIPTION("vhost transport for vsock ");
> > > --
> > > 2.34.1
> >

On Sun, Sep 29, 2024 at 07:35:35PM +0200, Aleksandr Mikhalitsyn wrote:
> On Sun, Sep 29, 2024 at 6:56 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Thu, Sep 26, 2024 at 06:16:40PM +0200, Alexander Mikhalitsyn wrote:
> > > Add an explicit MODULE_VERSION("0.0.1") specification
> > > for a vhost_vsock module. It is useful because it allows
> > > userspace to check if vhost_vsock is there when it is
> > > configured as a built-in.
> > >
> > > Without this change, there is no /sys/module/vhost_vsock directory.
> > >
> > > With this change:
> > > $ ls -la /sys/module/vhost_vsock/
> > > total 0
> > > drwxr-xr-x   2 root root    0 Sep 26 15:59 .
> > > drwxr-xr-x 100 root root    0 Sep 26 15:59 ..
> > > --w-------   1 root root 4096 Sep 26 15:59 uevent
> > > -r--r--r--   1 root root 4096 Sep 26 15:59 version
> > >
> > > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> >
> >
> 
> Dear Michael,
> 
> > Why not check that the misc device is registered?
> 
> It is possible to read /proc/misc and check if "241 vhost-vsock" is
> there, but it means that userspace
> needs to have a specific logic for vsock. At the same time, it's quite
> convenient to do something like:
>     if [ ! -d /sys/modules/vhost_vsock ]; then
>         modprobe vhost_vsock
>     fi
> 
> > I'd rather not add a new UAPI until actually necessary.
> 
> I don't insist. I decided to send this patch because, while I was
> debugging a non-related kernel issue
> on my local dev environment I accidentally discovered that LXD
> (containers and VM manager)
> fails to run VMs because it fails to load the vhost_vsock module (but
> it was built-in in my debug kernel
> and the module file didn't exist). Then I discovered that before
> trying to load a module we
> check if /sys/module/<module name> exists. And found that, for some
> reason /sys/module/vhost_vsock
> does not exist when vhost_vsock is configured as a built-in, and
> /sys/module/vhost_vsock *does* exist when
> vhost_vsock is loaded as a module. It looks like an inconsistency and
> I also checked that other modules in
> drivers/vhost have MODULE_VERSION specified and version is 0.0.1. I
> thought that this change looks legitimate
> and convenient for userspace consumers.
> 
> Kind regards,
> Alex


I'll ask you to put this explanation in the commit log,
and I'll pick this up.

> >
> > > ---
> > >  drivers/vhost/vsock.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > > index 802153e23073..287ea8e480b5 100644
> > > --- a/drivers/vhost/vsock.c
> > > +++ b/drivers/vhost/vsock.c
> > > @@ -956,6 +956,7 @@ static void __exit vhost_vsock_exit(void)
> > >
> > >  module_init(vhost_vsock_init);
> > >  module_exit(vhost_vsock_exit);
> > > +MODULE_VERSION("0.0.1");
> > >  MODULE_LICENSE("GPL v2");
> > >  MODULE_AUTHOR("Asias He");
> > >  MODULE_DESCRIPTION("vhost transport for vsock ");
> > > --
> > > 2.34.1
> >

On Sun, Sep 29, 2024 at 7:48 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Sun, Sep 29, 2024 at 07:35:35PM +0200, Aleksandr Mikhalitsyn wrote:
> > On Sun, Sep 29, 2024 at 6:56 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > >
> > > On Thu, Sep 26, 2024 at 06:16:40PM +0200, Alexander Mikhalitsyn wrote:
> > > > Add an explicit MODULE_VERSION("0.0.1") specification
> > > > for a vhost_vsock module. It is useful because it allows
> > > > userspace to check if vhost_vsock is there when it is
> > > > configured as a built-in.
> > > >
> > > > Without this change, there is no /sys/module/vhost_vsock directory.
> > > >
> > > > With this change:
> > > > $ ls -la /sys/module/vhost_vsock/
> > > > total 0
> > > > drwxr-xr-x   2 root root    0 Sep 26 15:59 .
> > > > drwxr-xr-x 100 root root    0 Sep 26 15:59 ..
> > > > --w-------   1 root root 4096 Sep 26 15:59 uevent
> > > > -r--r--r--   1 root root 4096 Sep 26 15:59 version
> > > >
> > > > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> > >
> > >
> >
> > Dear Michael,
> >
> > > Why not check that the misc device is registered?
> >
> > It is possible to read /proc/misc and check if "241 vhost-vsock" is
> > there, but it means that userspace
> > needs to have a specific logic for vsock. At the same time, it's quite
> > convenient to do something like:
> >     if [ ! -d /sys/modules/vhost_vsock ]; then
> >         modprobe vhost_vsock
> >     fi
> >
> > > I'd rather not add a new UAPI until actually necessary.
> >
> > I don't insist. I decided to send this patch because, while I was
> > debugging a non-related kernel issue
> > on my local dev environment I accidentally discovered that LXD
> > (containers and VM manager)
> > fails to run VMs because it fails to load the vhost_vsock module (but
> > it was built-in in my debug kernel
> > and the module file didn't exist). Then I discovered that before
> > trying to load a module we
> > check if /sys/module/<module name> exists. And found that, for some
> > reason /sys/module/vhost_vsock
> > does not exist when vhost_vsock is configured as a built-in, and
> > /sys/module/vhost_vsock *does* exist when
> > vhost_vsock is loaded as a module. It looks like an inconsistency and
> > I also checked that other modules in
> > drivers/vhost have MODULE_VERSION specified and version is 0.0.1. I
> > thought that this change looks legitimate
> > and convenient for userspace consumers.
> >
> > Kind regards,
> > Alex
>
>
> I'll ask you to put this explanation in the commit log,
> and I'll pick this up.

Have done:
https://lore.kernel.org/kvm/20240929182103.21882-1-aleksandr.mikhalitsyn@canonical.com

Thanks, Michael!

Kind regards,
Alex

>
> > >
> > > > ---
> > > >  drivers/vhost/vsock.c | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > > > index 802153e23073..287ea8e480b5 100644
> > > > --- a/drivers/vhost/vsock.c
> > > > +++ b/drivers/vhost/vsock.c
> > > > @@ -956,6 +956,7 @@ static void __exit vhost_vsock_exit(void)
> > > >
> > > >  module_init(vhost_vsock_init);
> > > >  module_exit(vhost_vsock_exit);
> > > > +MODULE_VERSION("0.0.1");
> > > >  MODULE_LICENSE("GPL v2");
> > > >  MODULE_AUTHOR("Asias He");
> > > >  MODULE_DESCRIPTION("vhost transport for vsock ");
> > > > --
> > > > 2.34.1
> > >
>