Re: [PATCH 4/7] vDPA: implement IRQ offloading helpers in vDPA core

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On 2020/7/12 下午10:49, Zhu Lingshan wrote:
This commit implements IRQ offloading helpers in vDPA core by
introducing two couple of functions:

vdpa_alloc_vq_irq() and vdpa_free_vq_irq(): request irq and free
irq, will setup irq offloading if irq_bypass is enabled.

vdpa_setup_irq() and vdpa_unsetup_irq(): supportive functions,
will call vhost_vdpa helpers.

Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>


This patch should go before patch 3.


---
  drivers/vdpa/vdpa.c   | 46 ++++++++++++++++++++++++++++++++++++++++++++++
  drivers/vhost/Kconfig |  1 +
  drivers/vhost/vdpa.c  |  2 ++
  include/linux/vdpa.h  | 11 +++++++++++
  4 files changed, 60 insertions(+)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index ff6562f..d8eba01 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -163,6 +163,52 @@ void vdpa_unregister_driver(struct vdpa_driver *drv)
  }
  EXPORT_SYMBOL_GPL(vdpa_unregister_driver);
+static void vdpa_setup_irq(struct vdpa_device *vdev, int qid, int irq)
+{
+	struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);
+
+#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS


Let's don't do the check here. It's the responsibility of driver to decide what it should do.


+	if (drv->setup_vq_irq)
+		drv->setup_vq_irq(vdev, qid, irq);
+#endif
+}
+
+static void vdpa_unsetup_irq(struct vdpa_device *vdev, int qid)
+{
+	struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);
+
+#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
+	if (drv->unsetup_vq_irq)
+		drv->unsetup_vq_irq(vdev, qid);
+#endif
+}
+
+int vdpa_alloc_vq_irq(struct device *dev, struct vdpa_device *vdev,
+		      unsigned int irq, irq_handler_t handler,
+		      unsigned long irqflags, const char *devname, void *dev_id,
+		      int qid)
+{
+	int ret;
+
+	ret = devm_request_irq(dev, irq, handler, irqflags, devname, dev_id);
+	if (ret)
+		dev_err(dev, "Failed to request irq for vq %d\n", qid);
+	else
+		vdpa_setup_irq(vdev, qid, irq);


I'd like to squash the vdpa_setup_irq logic here.


+
+	return ret;
+
+}
+EXPORT_SYMBOL_GPL(vdpa_alloc_vq_irq);
+
+void vdpa_free_vq_irq(struct device *dev, struct vdpa_device *vdev, int irq,
+			 int qid, void *dev_id)
+{
+	devm_free_irq(dev, irq, dev_id);
+	vdpa_unsetup_irq(vdev, qid);
+}
+EXPORT_SYMBOL_GPL(vdpa_free_vq_irq);
+
  static int vdpa_init(void)
  {
  	return bus_register(&vdpa_bus);
diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig


Let squash the vhost patch into patch 3.


index d3688c6..587fbae 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 92683e4..6e25158 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -1020,6 +1020,8 @@ static void vhost_vdpa_remove(struct vdpa_device *vdpa)
  	},
  	.probe	= vhost_vdpa_probe,
  	.remove	= vhost_vdpa_remove,
+	.setup_vq_irq = vhost_vdpa_setup_vq_irq,
+	.unsetup_vq_irq = vhost_vdpa_unsetup_vq_irq,
  };
static int __init vhost_vdpa_init(void)
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 239db79..9f9b245 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -220,17 +220,28 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
int vdpa_register_device(struct vdpa_device *vdev);
  void vdpa_unregister_device(struct vdpa_device *vdev);
+int vdpa_alloc_vq_irq(struct device *dev, struct vdpa_device *vdev,
+		      unsigned int irq, irq_handler_t handler,
+		      unsigned long irqflags, const char *devname, void *dev_id,
+		      int qid);
+void vdpa_free_vq_irq(struct device *dev, struct vdpa_device *vdev, int irq,
+		      int qid, void *dev_id);


You need to document the devres implications of those two helpers.


+
/**
   * vdpa_driver - operations for a vDPA driver
   * @driver: underlying device driver
   * @probe: the function to call when a device is found.  Returns 0 or -errno.
   * @remove: the function to call when a device is removed.
+ * @setup_vq_irq: setup irq bypass for a vhost_vdpa vq.
+ * @unsetup_vq_irq: unsetup irq bypass for a vhost_vdpa vq.


Though irq bypass is used by vhost-vdpa, it's not necessarily to be true in the future. So it's better not to mention irqbypass in the doc here.

Thanks


   */
  struct vdpa_driver {
  	struct device_driver driver;
  	int (*probe)(struct vdpa_device *vdev);
  	void (*remove)(struct vdpa_device *vdev);
+	void (*setup_vq_irq)(struct vdpa_device *vdev, int qid, int irq);
+	void (*unsetup_vq_irq)(struct vdpa_device *vdev, int qid);
  };
#define vdpa_register_driver(drv) \

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