Messages in this thread | | | Date | Tue, 9 Nov 2021 14:31:59 +0100 | From | Stefano Garzarella <> | Subject | Re: [PATCH] vdpa: add driver_override support |
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On Tue, Nov 09, 2021 at 08:10:58AM -0500, Michael S. Tsirkin wrote: >On Mon, Nov 08, 2021 at 06:05:29PM +0100, Stefano Garzarella wrote: >> On Fri, Nov 5, 2021 at 4:01 AM Jason Wang <jasowang@redhat.com> wrote: >> > >> > On Fri, Nov 5, 2021 at 12:17 AM Stefano Garzarella <sgarzare@redhat.com> wrote: >> > > >> > > `driver_override` allows to control which of the vDPA bus drivers >> > > binds to a vDPA device. >> > > >> > > If `driver_override` is not set, the previous behaviour is followed: >> > > devices use the first vDPA bus driver loaded (unless auto binding >> > > is disabled). >> > > >> > > Tested on Fedora 34 with driverctl(8): >> > > $ modprobe virtio-vdpa >> > > $ modprobe vhost-vdpa >> > > $ modprobe vdpa-sim-net >> > > >> > > $ vdpa dev add mgmtdev vdpasim_net name dev1 >> > > >> > > # dev1 is attached to the first vDPA bus driver loaded >> > > $ driverctl -b vdpa list-devices >> > > dev1 virtio_vdpa >> > > >> > > $ driverctl -b vdpa set-override dev1 vhost_vdpa >> > > >> > > $ driverctl -b vdpa list-devices >> > > dev1 vhost_vdpa [*] >> > > >> > > Note: driverctl(8) integrates with udev so the binding is >> > > preserved. >> > > >> > > Suggested-by: Jason Wang <jasowang@redhat.com> >> > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> >> > > --- >> > > include/linux/vdpa.h | 2 ++ >> > > drivers/vdpa/vdpa.c | 74 ++++++++++++++++++++++++++++++++++++++++++++ >> > > 2 files changed, 76 insertions(+) >> > > >> > > diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h >> > > index c3011ccda430..ae34015b37b7 100644 >> > > --- a/include/linux/vdpa.h >> > > +++ b/include/linux/vdpa.h >> > > @@ -64,6 +64,7 @@ struct vdpa_mgmt_dev; >> > > * struct vdpa_device - representation of a vDPA device >> > > * @dev: underlying device >> > > * @dma_dev: the actual device that is performing DMA >> > > + * @driver_override: driver name to force a match >> > >> > This seems useless? >> > >> > > * @config: the configuration ops for this device. >> > > * @cf_mutex: Protects get and set access to configuration layout. >> > > * @index: device index >> > > @@ -76,6 +77,7 @@ struct vdpa_mgmt_dev; >> > > struct vdpa_device { >> > > struct device dev; >> > > struct device *dma_dev; >> > > + const char *driver_override; >> > > const struct vdpa_config_ops *config; >> > > struct mutex cf_mutex; /* Protects get/set config */ >> > > unsigned int index; >> > > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c >> > > index 7332a74a4b00..659231bbfee8 100644 >> > > --- a/drivers/vdpa/vdpa.c >> > > +++ b/drivers/vdpa/vdpa.c >> > > @@ -52,8 +52,81 @@ static void vdpa_dev_remove(struct device *d) >> > > drv->remove(vdev); >> > > } >> > > >> > > +static int vdpa_dev_match(struct device *dev, struct device_driver *drv) >> > > +{ >> > > + struct vdpa_device *vdev = dev_to_vdpa(dev); >> > > + >> > > + /* Check override first, and if set, only use the named driver */ >> > > + if (vdev->driver_override) >> > > + return strcmp(vdev->driver_override, drv->name) == 0; >> > > + >> > > + /* Currently devices must be supported by all vDPA bus drivers */ >> > > + return 1; >> > > +} >> > > + >> > > +static ssize_t driver_override_store(struct device *dev, >> > > + struct device_attribute *attr, >> > > + const char *buf, size_t count) >> > > +{ >> > > + struct vdpa_device *vdev = dev_to_vdpa(dev); >> > > + const char *driver_override, *old; >> > > + char *cp; >> > > + >> > > + /* We need to keep extra room for a newline */ >> > > + if (count >= (PAGE_SIZE - 1)) >> > > + return -EINVAL; >> > > + >> > > + driver_override = kstrndup(buf, count, GFP_KERNEL); >> > > + if (!driver_override) >> > > + return -ENOMEM; >> > > + >> > > + cp = strchr(driver_override, '\n'); >> > > + if (cp) >> > > + *cp = '\0'; >> > > + >> > > + device_lock(dev); >> > > + old = vdev->driver_override; >> > > + if (strlen(driver_override)) { >> > > + vdev->driver_override = driver_override; >> > > + } else { >> > > + kfree(driver_override); >> > > + vdev->driver_override = NULL; >> > > + } >> > > + device_unlock(dev); >> > > + >> > > + kfree(old); >> > > + >> > > + return count; >> > > +} >> > > + >> > > +static ssize_t driver_override_show(struct device *dev, >> > > + struct device_attribute *attr, char *buf) >> > > +{ >> > > + struct vdpa_device *vdev = dev_to_vdpa(dev); >> > > + ssize_t len; >> > > + >> > > + device_lock(dev); >> > > + len = snprintf(buf, PAGE_SIZE, "%s\n", vdev->driver_override); >> > > + device_unlock(dev); >> > > + >> > > + return len; >> > > +} >> > > +static DEVICE_ATTR_RW(driver_override); >> > > + >> > > +static struct attribute *vdpa_dev_attrs[] = { >> > > + &dev_attr_driver_override.attr, >> > > + NULL, >> > > +}; >> > > + >> > > +static const struct attribute_group vdpa_dev_group = { >> > > + .attrs = vdpa_dev_attrs, >> > > +}; >> > > +__ATTRIBUTE_GROUPS(vdpa_dev); >> > > + >> > > static struct bus_type vdpa_bus = { >> > > .name = "vdpa", >> > > + .dev_groups = vdpa_dev_groups, >> > >> > This reminds me that we probably need to document the sysfs interface >> > in Documentation/ABI/testing/sysfs-bus-vdpa. >> > >> > But it's not the fault of this patch which look good. >> >> Michael, Jason, about Documentation/ABI/testing/sysfs-bus-vdpa, do you >> think is better to send a follow up patch/series, maybe including also >> others entries (e.g. bind, unbind) or a v2 including the documentation >> of `driver_ovveride`? >> >> Thanks, >> Stefano > >I'd include it as a patch in series. >
Okay, so I'll send the documentation in a followup series.
Thanks, Stefano
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