Linux Virtualization - Nov 2016 - [virtio-dev] Re: [PATCH v2 1/2] virtio: introduce little edian functions for virtio_cread/write# family

On Tue, Nov 22, 2016 at 04:10:22PM +0800, Gonglei wrote:
> Virtio modern devices are always little edian, let's introduce
> the LE functions for read/write configuration space for
> virtio modern devices, which avoid complaint by Sparse when
> we use the virtio_creaed/virtio_cwrite in VIRTIO_1 devices.
> 
> Signed-off-by: Gonglei <arei.gonglei at huawei.com>
> ---
>  include/linux/virtio_config.h | 45
+++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
> 
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 26c155b..de05707 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -414,4 +414,49 @@ static inline void virtio_cwrite64(struct
virtio_device *vdev,
>  		_r;							\
>  	})
>  
> +static inline __le16 virtio_cread16_le(struct virtio_device *vdev,
> +				 unsigned int offset)
> +{
> +	__le16 ret;
> +
> +	vdev->config->get(vdev, offset, &ret, sizeof(ret));
> +	return ret;
> +}
> +
> +static inline void virtio_cwrite16_le(struct virtio_device *vdev,
> +				   unsigned int offset, __le16 val)
> +{
> +	vdev->config->set(vdev, offset, &val, sizeof(val));
> +}
> +
> +static inline __le32 virtio_cread32_le(struct virtio_device *vdev,
> +				 unsigned int offset)
> +{
> +	__le32 ret;
> +
> +	vdev->config->get(vdev, offset, &ret, sizeof(ret));
> +	return ret;
> +}
> +
> +static inline void virtio_cwrite32_le(struct virtio_device *vdev,
> +				   unsigned int offset, __le32 val)
> +{
> +	vdev->config->set(vdev, offset, &val, sizeof(val));
> +}
> +
> +static inline __le64 virtio_cread64_le(struct virtio_device *vdev,
> +				 unsigned int offset)
> +{
> +	__le64 ret;
> +
> +	__virtio_cread_many(vdev, offset, &ret, 1, sizeof(ret));
> +	return ret;
> +}
> +
> +static inline void virtio_cwrite64_le(struct virtio_device *vdev,
> +				   unsigned int offset, __le64 val)
> +{
> +	vdev->config->set(vdev, offset, &val, sizeof(val));
> +}
> +
>  #endif /* _LINUX_VIRTIO_CONFIG_H */
Could you please better explain what is the issue you are facing?
virtio_cwrite/virtio_cread all accept and return native types.

If you want it in LE format, swap it!


> -- 
> 1.8.3.1
>

Hi Michael,

Thanks for your feedback firstly!
> -----Original Message-----
> From: virtio-dev at lists.oasis-open.org [mailto:virtio-dev at
lists.oasis-open.org]
> On Behalf Of Michael S. Tsirkin
> Sent: Sunday, November 27, 2016 11:33 AM
> To: Gonglei (Arei)
> Subject: [virtio-dev] Re: [PATCH v2 1/2] virtio: introduce little edian
functions for
> virtio_cread/write# family
> 
> On Tue, Nov 22, 2016 at 04:10:22PM +0800, Gonglei wrote:
> > Virtio modern devices are always little edian, let's introduce
> > the LE functions for read/write configuration space for
> > virtio modern devices, which avoid complaint by Sparse when
> > we use the virtio_creaed/virtio_cwrite in VIRTIO_1 devices.
> >
> > Signed-off-by: Gonglei <arei.gonglei at huawei.com>
> > ---
> >  include/linux/virtio_config.h | 45
> +++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 45 insertions(+)
> >
> > diff --git a/include/linux/virtio_config.h
b/include/linux/virtio_config.h
> > index 26c155b..de05707 100644
> > --- a/include/linux/virtio_config.h
> > +++ b/include/linux/virtio_config.h
> > @@ -414,4 +414,49 @@ static inline void virtio_cwrite64(struct
virtio_device
> *vdev,
> >  		_r;							\
> >  	})
> >
> > +static inline __le16 virtio_cread16_le(struct virtio_device *vdev,
> > +				 unsigned int offset)
> > +{
> > +	__le16 ret;
> > +
> > +	vdev->config->get(vdev, offset, &ret, sizeof(ret));
> > +	return ret;
> > +}
> > +
> > +static inline void virtio_cwrite16_le(struct virtio_device *vdev,
> > +				   unsigned int offset, __le16 val)
> > +{
> > +	vdev->config->set(vdev, offset, &val, sizeof(val));
> > +}
> > +
> > +static inline __le32 virtio_cread32_le(struct virtio_device *vdev,
> > +				 unsigned int offset)
> > +{
> > +	__le32 ret;
> > +
> > +	vdev->config->get(vdev, offset, &ret, sizeof(ret));
> > +	return ret;
> > +}
> > +
> > +static inline void virtio_cwrite32_le(struct virtio_device *vdev,
> > +				   unsigned int offset, __le32 val)
> > +{
> > +	vdev->config->set(vdev, offset, &val, sizeof(val));
> > +}
> > +
> > +static inline __le64 virtio_cread64_le(struct virtio_device *vdev,
> > +				 unsigned int offset)
> > +{
> > +	__le64 ret;
> > +
> > +	__virtio_cread_many(vdev, offset, &ret, 1, sizeof(ret));
> > +	return ret;
> > +}
> > +
> > +static inline void virtio_cwrite64_le(struct virtio_device *vdev,
> > +				   unsigned int offset, __le64 val)
> > +{
> > +	vdev->config->set(vdev, offset, &val, sizeof(val));
> > +}
> > +
> >  #endif /* _LINUX_VIRTIO_CONFIG_H */
> 
> Could you please better explain what is the issue you are facing?
> virtio_cwrite/virtio_cread all accept and return native types.
> 
virtio_cwrite/virtio_cread are used to write/read configuration
space for virtio devices. For virtio-crypto device, I used __le32/64 directly
in struct virtio_crypto_config. The sparse reports warnings if I use
virtio_cread()
for virtio-crypto device.

Furthermore, it means the warnings exist for all VIRTIO_1 devices because
they are definitely LE, which it's not necessary to use
virtio_to_cpu/cpu_to_virtio.


PS: I googled a discussion about this topic for virtio-input device, pls see:
 http://linux.kernel.narkive.com/3argfbWz/patch-1-1-add-virtio-input-driver

Regards,
-Gonglei
> If you want it in LE format, swap it!
> 
> 
> 
> > --
> > 1.8.3.1
> >
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: virtio-dev-unsubscribe at lists.oasis-open.org
> For additional commands, e-mail: virtio-dev-help at lists.oasis-open.org

On Mon, Nov 28, 2016 at 01:56:04AM +0000, Gonglei (Arei)
wrote:
> Hi Michael,
> 
> Thanks for your feedback firstly!
> 
> > -----Original Message-----
> > From: virtio-dev at lists.oasis-open.org [mailto:virtio-dev at
lists.oasis-open.org]
> > On Behalf Of Michael S. Tsirkin
> > Sent: Sunday, November 27, 2016 11:33 AM
> > To: Gonglei (Arei)
> > Subject: [virtio-dev] Re: [PATCH v2 1/2] virtio: introduce little
edian functions for
> > virtio_cread/write# family
> > 
> > On Tue, Nov 22, 2016 at 04:10:22PM +0800, Gonglei wrote:
> > > Virtio modern devices are always little edian, let's
introduce
> > > the LE functions for read/write configuration space for
> > > virtio modern devices, which avoid complaint by Sparse when
> > > we use the virtio_creaed/virtio_cwrite in VIRTIO_1 devices.
> > >
> > > Signed-off-by: Gonglei <arei.gonglei at huawei.com>
> > > ---
> > >  include/linux/virtio_config.h | 45
> > +++++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 45 insertions(+)
> > >
> > > diff --git a/include/linux/virtio_config.h
b/include/linux/virtio_config.h
> > > index 26c155b..de05707 100644
> > > --- a/include/linux/virtio_config.h
> > > +++ b/include/linux/virtio_config.h
> > > @@ -414,4 +414,49 @@ static inline void virtio_cwrite64(struct
virtio_device
> > *vdev,
> > >  		_r;							\
> > >  	})
> > >
> > > +static inline __le16 virtio_cread16_le(struct virtio_device
*vdev,
> > > +				 unsigned int offset)
> > > +{
> > > +	__le16 ret;
> > > +
> > > +	vdev->config->get(vdev, offset, &ret, sizeof(ret));
> > > +	return ret;
> > > +}
> > > +
> > > +static inline void virtio_cwrite16_le(struct virtio_device
*vdev,
> > > +				   unsigned int offset, __le16 val)
> > > +{
> > > +	vdev->config->set(vdev, offset, &val, sizeof(val));
> > > +}
> > > +
> > > +static inline __le32 virtio_cread32_le(struct virtio_device
*vdev,
> > > +				 unsigned int offset)
> > > +{
> > > +	__le32 ret;
> > > +
> > > +	vdev->config->get(vdev, offset, &ret, sizeof(ret));
> > > +	return ret;
> > > +}
> > > +
> > > +static inline void virtio_cwrite32_le(struct virtio_device
*vdev,
> > > +				   unsigned int offset, __le32 val)
> > > +{
> > > +	vdev->config->set(vdev, offset, &val, sizeof(val));
> > > +}
> > > +
> > > +static inline __le64 virtio_cread64_le(struct virtio_device
*vdev,
> > > +				 unsigned int offset)
> > > +{
> > > +	__le64 ret;
> > > +
> > > +	__virtio_cread_many(vdev, offset, &ret, 1, sizeof(ret));
> > > +	return ret;
> > > +}
> > > +
> > > +static inline void virtio_cwrite64_le(struct virtio_device
*vdev,
> > > +				   unsigned int offset, __le64 val)
> > > +{
> > > +	vdev->config->set(vdev, offset, &val, sizeof(val));
> > > +}
> > > +
> > >  #endif /* _LINUX_VIRTIO_CONFIG_H */
> > 
> > Could you please better explain what is the issue you are facing?
> > virtio_cwrite/virtio_cread all accept and return native types.
> > 
> virtio_cwrite/virtio_cread are used to write/read configuration
> space for virtio devices. For virtio-crypto device, I used __le32/64
directly
> in struct virtio_crypto_config. The sparse reports warnings if I use
virtio_cread()
> for virtio-crypto device.
I suspect that's because you are doing cread into an le32 variable.


> Furthermore, it means the warnings exist for all VIRTIO_1 devices because
> they are definitely LE, which it's not necessary to use
virtio_to_cpu/cpu_to_virtio.
> 
> 
> PS: I googled a discussion about this topic for virtio-input device, pls
see:
>  http://linux.kernel.narkive.com/3argfbWz/patch-1-1-add-virtio-input-driver
> 
> Regards,
> -Gonglei
Looks like we changed the macros since - at least ATM
virtio_console_config uses __u16 fields (which is probably a bug -
I'll look into fixing it up) and they
do not seem to trigger warnings.

> > If you want it in LE format, swap it!
> > 
> > 
> > 
> > > --
> > > 1.8.3.1
> > >
> > 
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: virtio-dev-unsubscribe at lists.oasis-open.org
> > For additional commands, e-mail: virtio-dev-help at
lists.oasis-open.org