On 2020/7/15 下午4:56, Zhu, Lingshan wrote:

On 7/15/2020 4:51 PM, Jason Wang wrote:

quoted

On 2020/7/13 下午5:47, Zhu, Lingshan wrote:

quoted

On 7/13/2020 4:22 PM, Jason Wang wrote:

quoted

On 2020/7/12 下午10:49, Zhu Lingshan wrote:

quoted

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.

Signed-off-by: Zhu Lingshan <redacted>
---
  drivers/vhost/vdpa.c | 69 
++++++++++++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 69 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 2fcc422..92683e4 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -115,6 +115,63 @@ static irqreturn_t vhost_vdpa_config_cb(void 

*private)
      return IRQ_HANDLED;
  }
  +static void vhost_vdpa_setup_vq_irq(struct vdpa_device *dev, 
int qid, int irq)
+{
+    struct vhost_vdpa *v = vdpa_get_drvdata(dev);
+    struct vhost_virtqueue *vq = &v->vqs[qid];
+    int ret;
+
+    vq_err(vq, "setup irq bypass for vq %d with irq = %d\n", qid, 
irq);
+    spin_lock(&vq->call_ctx.ctx_lock);
+    if (!vq->call_ctx.ctx)
+        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);
+
+    if (unlikely(ret))
+        vq_err(vq,
+        "irq bypass producer (token %p registration fails: %d\n",
+        vq->call_ctx.producer.token, ret);

Not sure this deserves a vq_err(), irq will be relayed through 
eventfd if irq bypass manager can't work.

OK, I see vq_err() will eventfd_signal err_ctx than just print a 
message, will remove all vq_err().

quoted

quoted

+}
+
+static void vhost_vdpa_unsetup_vq_irq(struct vdpa_device *dev, 
int qid)
+{
+    struct vhost_vdpa *v = vdpa_get_drvdata(dev);
+    struct vhost_virtqueue *vq = &v->vqs[qid];
+
+    spin_lock(&vq->call_ctx.ctx_lock);
+ irq_bypass_unregister_producer(&vq->call_ctx.producer);
+    spin_unlock(&vq->call_ctx.ctx_lock);
+
+    vq_err(vq, "unsetup irq bypass for vq %d\n", qid);

Why call vq_err() here?

quoted

+}
+
+static void vhost_vdpa_update_vq_irq(struct vhost_virtqueue *vq)
+{
+    struct eventfd_ctx *ctx;
+    void *token;
+
+    spin_lock(&vq->call_ctx.ctx_lock);
+    ctx = vq->call_ctx.ctx;
+    token = vq->call_ctx.producer.token;
+    if (ctx == token)
+        return;

Need do unlock here.

sure!

quoted

quoted

+
+    if (!ctx && token)
+ irq_bypass_unregister_producer(&vq->call_ctx.producer);
+
+    if (ctx && ctx != token) {
+ irq_bypass_unregister_producer(&vq->call_ctx.producer);
+        vq->call_ctx.producer.token = ctx;
+ irq_bypass_register_producer(&vq->call_ctx.producer);
+    }
+
+    spin_unlock(&vq->call_ctx.ctx_lock);

This should be rare so I'd use simple codes just do unregister and 
register.

do you mean remove "if (ctx && ctx != token)"? I think this could be 
useful, we should only update it when ctx!=NULL and ctx!= existing 
token.

I meant something like:

unregister();
vq->call_ctx.producer.token = ctx;
register();

This is what we are doing now, or I must missed somethig:
if (ctx && ctx != token) {
	irq_bypass_unregister_producer(&vq->call_ctx.producer);
	vq->call_ctx.producer.token = ctx;
	irq_bypass_register_producer(&vq->call_ctx.producer);

}

It just unregister and register.

I meant there's probably no need for the check and another check and 
unregister before. The whole function is as simple as I suggested above.

Thanks

Thanks,
BR
Zhu Lingshan