Michael S. Tsirkin
2020-Aug-04 09:36 UTC
[PATCH V5 4/6] vhost_vdpa: implement IRQ offloading in vhost_vdpa
On Tue, Aug 04, 2020 at 05:31:38PM +0800, Zhu, Lingshan wrote:> > On 8/4/2020 4:51 PM, Jason Wang wrote: > > > On 2020/7/31 ??2:55, Zhu Lingshan wrote: > > This patch introduce a set of functions for setup/unsetup > and update irq offloading respectively by register/unregister > and re-register the irq_bypass_producer. > > With these functions, this commit can setup/unsetup > irq offloading through setting DRIVER_OK/!DRIVER_OK, and > update irq offloading through SET_VRING_CALL. > > Signed-off-by: Zhu Lingshan <lingshan.zhu at intel.com> > Suggested-by: Jason Wang <jasowang at redhat.com> > --- > ? drivers/vhost/Kconfig |? 1 + > ? drivers/vhost/vdpa.c? | 79 > ++++++++++++++++++++++++++++++++++++++++++- > ? 2 files changed, 79 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig > index d3688c6afb87..587fbae06182 100644 > --- a/drivers/vhost/Kconfig > +++ b/drivers/vhost/Kconfig > @@ -65,6 +65,7 @@ config VHOST_VDPA > ????? tristate "Vhost driver for vDPA-based backend" > ????? depends on EVENTFD > ????? select VHOST > +??? select IRQ_BYPASS_MANAGER > ????? depends on VDPA > ????? help > ??????? This kernel module can be loaded in host kernel to accelerate > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index df3cf386b0cd..278ea2f00172 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -115,6 +115,55 @@ static irqreturn_t vhost_vdpa_config_cb(void > *private) > ????? return IRQ_HANDLED; > ? } > ? +static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid) > +{ > +??? struct vhost_virtqueue *vq = &v->vqs[qid]; > +??? const struct vdpa_config_ops *ops = v->vdpa->config; > +??? struct vdpa_device *vdpa = v->vdpa; > +??? int ret, irq; > + > +??? spin_lock(&vq->call_ctx.ctx_lock); > +??? irq = ops->get_vq_irq(vdpa, qid); > +??? if (!vq->call_ctx.ctx || irq < 0) { > +??????? spin_unlock(&vq->call_ctx.ctx_lock); > +??????? return; > +??? } > + > +??? vq->call_ctx.producer.token = vq->call_ctx.ctx; > +??? vq->call_ctx.producer.irq = irq; > +??? ret = irq_bypass_register_producer(&vq->call_ctx.producer); > +??? spin_unlock(&vq->call_ctx.ctx_lock); > +} > + > +static void vhost_vdpa_unsetup_vq_irq(struct vhost_vdpa *v, u16 qid) > +{ > +??? struct vhost_virtqueue *vq = &v->vqs[qid]; > + > +??? spin_lock(&vq->call_ctx.ctx_lock); > +??? irq_bypass_unregister_producer(&vq->call_ctx.producer); > > > > Any reason for not checking vq->call_ctx.producer.irq as below here? > > we only need ctx as a token to unregister vq from irq bypass manager, if vq->call_ctx.producer.irq is 0, means it is a unused or disabled vq, no harm if we > perform an unregister on it. > > > > +??? spin_unlock(&vq->call_ctx.ctx_lock); > +} > + > +static void vhost_vdpa_update_vq_irq(struct vhost_virtqueue *vq) > +{ > +??? spin_lock(&vq->call_ctx.ctx_lock); > +??? /* > +???? * if it has a non-zero irq, means there is a > +???? * previsouly registered irq_bypass_producer, > +???? * we should update it when ctx (its token) > +???? * changes. > +???? */ > +??? if (!vq->call_ctx.producer.irq) { > +??????? spin_unlock(&vq->call_ctx.ctx_lock); > +??????? return; > +??? } > + > +??? irq_bypass_unregister_producer(&vq->call_ctx.producer); > +??? vq->call_ctx.producer.token = vq->call_ctx.ctx; > +??? irq_bypass_register_producer(&vq->call_ctx.producer); > +??? spin_unlock(&vq->call_ctx.ctx_lock); > +} > > > > I think setup_irq() and update_irq() could be unified with the following > logic: > > irq_bypass_unregister_producer(&vq->call_ctx.producer); > irq = ops->get_vq_irq(vdpa, qid); > ??? if (!vq->call_ctx.ctx || irq < 0) { > ??? ??? spin_unlock(&vq->call_ctx.ctx_lock); > ??? ??? return; > ??? } > > vq->call_ctx.producer.token = vq->call_ctx.ctx; > vq->call_ctx.producer.irq = irq; > ret = irq_bypass_register_producer(&vq->call_ctx.producer); > > Yes, this code piece can do both register and update. Though it's rare to call undate_irq(), however > setup_irq() is very likely to be called for every vq, so this may cause several rounds of useless irq_bypass_unregister_producer(). > is it worth for simplify the code? > > > + > ? static void vhost_vdpa_reset(struct vhost_vdpa *v) > ? { > ????? struct vdpa_device *vdpa = v->vdpa; > @@ -155,11 +204,15 @@ static long vhost_vdpa_set_status(struct > vhost_vdpa *v, u8 __user *statusp) > ? { > ????? struct vdpa_device *vdpa = v->vdpa; > ????? const struct vdpa_config_ops *ops = vdpa->config; > -??? u8 status; > +??? u8 status, status_old; > +??? int nvqs = v->nvqs; > +??? u16 i; > ? ????? if (copy_from_user(&status, statusp, sizeof(status))) > ????????? return -EFAULT; > ? +??? status_old = ops->get_status(vdpa); > + > ????? /* > ?????? * Userspace shouldn't remove status bits unless reset the > ?????? * status to 0. > @@ -169,6 +222,15 @@ static long vhost_vdpa_set_status(struct > vhost_vdpa *v, u8 __user *statusp) > ? ????? ops->set_status(vdpa, status); > ? +??? /* vq irq is not expected to be changed once DRIVER_OK is set */ > > > > Let's move this comment to the get_vq_irq bus operation. > > OK, can do! > >Patch on top pls, these are in my tree now.> > +??? if ((status & VIRTIO_CONFIG_S_DRIVER_OK) && !(status_old & > VIRTIO_CONFIG_S_DRIVER_OK)) > +??????? for (i = 0; i < nvqs; i++) > +??????????? vhost_vdpa_setup_vq_irq(v, i); > + > +??? if ((status_old & VIRTIO_CONFIG_S_DRIVER_OK) && !(status & > VIRTIO_CONFIG_S_DRIVER_OK)) > +??????? for (i = 0; i < nvqs; i++) > +??????????? vhost_vdpa_unsetup_vq_irq(v, i); > + > ????? return 0; > ? } > ? @@ -332,6 +394,7 @@ static long vhost_vdpa_set_config_call(struct > vhost_vdpa *v, u32 __user *argp) > ? ????? return 0; > ? } > + > ? static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int > cmd, > ???????????????????? void __user *argp) > ? { > @@ -390,6 +453,7 @@ static long vhost_vdpa_vring_ioctl(struct > vhost_vdpa *v, unsigned int cmd, > ????????????? cb.private = NULL; > ????????? } > ????????? ops->set_vq_cb(vdpa, idx, &cb); > +??????? vhost_vdpa_update_vq_irq(vq); > ????????? break; > ? ????? case VHOST_SET_VRING_NUM: > @@ -765,6 +829,18 @@ static int vhost_vdpa_open(struct inode *inode, > struct file *filep) > ????? return r; > ? } > ? +static void vhost_vdpa_clean_irq(struct vhost_vdpa *v) > +{ > +??? struct vhost_virtqueue *vq; > +??? int i; > + > +??? for (i = 0; i < v->nvqs; i++) { > +??????? vq = &v->vqs[i]; > +??????? if (vq->call_ctx.producer.irq) > +??????????? irq_bypass_unregister_producer(&vq->call_ctx.producer); > +??? } > +} > > > > Why not using vhost_vdpa_unsetup_vq_irq()? > > IMHO, in this cleanup phase, the device is almost dead, user space won't change ctx anymore, so I think we don't need to check ctx or irq, can just unregister it. > > Thanks! > > > Thanks > > > > + > ? static int vhost_vdpa_release(struct inode *inode, struct file > *filep) > ? { > ????? struct vhost_vdpa *v = filep->private_data; > @@ -777,6 +853,7 @@ static int vhost_vdpa_release(struct inode *inode, > struct file *filep) > ????? vhost_vdpa_iotlb_free(v); > ????? vhost_vdpa_free_domain(v); > ????? vhost_vdpa_config_put(v); > +??? vhost_vdpa_clean_irq(v); > ????? vhost_dev_cleanup(&v->vdev); > ????? kfree(v->vdev.vqs); > ????? mutex_unlock(&d->mutex); > > >