On Mon, Nov 28, 2016 at 04:34:56AM +0200, Michael S. Tsirkin wrote: > 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@xxxxxxxxxxxxxxxxxxxx [mailto:virtio-dev@xxxxxxxxxxxxxxxxxxxx] > > > 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@xxxxxxxxxx> > > > > --- > > > > 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. Sorry, I recall now. We use u32 and similar types in the config space, and endian-ness is implicit. This works fine if you are using virtio_cread interfaces which will swap to/from LE for you. What doesn't work correctly is shadowing the whole config space using ->get since that does not byte-swap. so just don't do it. I would say just do what everyone does in this version and we can revisit this later. > > > > If you want it in LE format, swap it! > > > > > > > > > > > > > -- > > > > 1.8.3.1 > > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: virtio-dev-unsubscribe@xxxxxxxxxxxxxxxxxxxx > > > For additional commands, e-mail: virtio-dev-help@xxxxxxxxxxxxxxxxxxxx _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
