[Qemu-devel] [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting AER

[Qemu-devel] [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting AER

[Pandarathil, Vijaymohan R]

	- New ioctl which is used to pass the eventfd that is signaled when
          an error occurs in the vfio_pci_device

	- Register pci_error_handler for the vfio_pci driver

	- When the device encounters an error, the error handler registered by
          the vfio_pci driver gets invoked by the AER infrastructure

	- In the error handler, signal the eventfd registered for the device.

	- This results in the qemu eventfd handler getting invoked and
          appropriate action taken for the guest.

Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
---
 drivers/vfio/pci/vfio_pci.c         | 29 +++++++++++++++++++++++++++++
 drivers/vfio/pci/vfio_pci_private.h |  1 +
 drivers/vfio/vfio.c                 |  8 ++++++++
 include/linux/vfio.h                |  1 +
 include/uapi/linux/vfio.h           |  9 +++++++++
 5 files changed, 48 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 6c11994..4ae9526 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -207,6 +207,8 @@ static long vfio_pci_ioctl(void *device_data,
 		if (vdev->reset_works)
 			info.flags |= VFIO_DEVICE_FLAGS_RESET;
 
+		info.flags |= VFIO_DEVICE_FLAGS_AER_NOTIFY;
+
 		info.num_regions = VFIO_PCI_NUM_REGIONS;
 		info.num_irqs = VFIO_PCI_NUM_IRQS;
 
@@ -348,6 +350,19 @@ static long vfio_pci_ioctl(void *device_data,
 
 		return ret;
 
+	} else if (cmd == VFIO_DEVICE_SET_ERRFD) {
+		int32_t fd = (int32_t)arg;
+
+		if (fd < 0)
+			return -EINVAL;
+
+		vdev->err_trigger = eventfd_ctx_fdget(fd);
+
+		if (IS_ERR(vdev->err_trigger))
+			return PTR_ERR(vdev->err_trigger);
+
+		return 0;
+
 	} else if (cmd == VFIO_DEVICE_RESET)
 		return vdev->reset_works ?
 			pci_reset_function(vdev->pdev) : -EINVAL;
@@ -527,11 +542,25 @@ static void vfio_pci_remove(struct pci_dev *pdev)
 	kfree(vdev);
 }
 
+static pci_ers_result_t vfio_err_detected(struct pci_dev *pdev,
+				pci_channel_state_t state)
+{
+	struct vfio_pci_device *vdev = vfio_get_vdev(&pdev->dev);
+
+	eventfd_signal(vdev->err_trigger, 1);
+	return PCI_ERS_RESULT_CAN_RECOVER;
+}
+
+static const struct pci_error_handlers vfio_err_handlers = {
+	.error_detected = vfio_err_detected,
+};
+
 static struct pci_driver vfio_pci_driver = {
 	.name		= "vfio-pci",
 	.id_table	= NULL, /* only dynamic ids */
 	.probe		= vfio_pci_probe,
 	.remove		= vfio_pci_remove,
+	.err_handler	= &vfio_err_handlers,
 };
 
 static void __exit vfio_pci_cleanup(void)
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 611827c..daee62f 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -55,6 +55,7 @@ struct vfio_pci_device {
 	bool			bardirty;
 	struct pci_saved_state	*pci_saved_state;
 	atomic_t		refcnt;
+	struct eventfd_ctx	*err_trigger;
 };
 
 #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 56097c6..5ed5a54 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -693,6 +693,14 @@ void *vfio_del_group_dev(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(vfio_del_group_dev);
 
+void *vfio_get_vdev(struct device *dev)
+{
+	struct vfio_device *device = dev_get_drvdata(dev);
+
+	return device->device_data;
+}
+EXPORT_SYMBOL_GPL(vfio_get_vdev);
+
 /**
  * VFIO base fd, /dev/vfio/vfio
  */
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index ab9e862..3c97b03 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -45,6 +45,7 @@ extern int vfio_add_group_dev(struct device *dev,
 			      void *device_data);
 
 extern void *vfio_del_group_dev(struct device *dev);
+extern void *vfio_get_vdev(struct device *dev);
 
 /**
  * struct vfio_iommu_driver_ops - VFIO IOMMU driver callbacks
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 4758d1b..fa67213 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -147,6 +147,7 @@ struct vfio_device_info {
 	__u32	flags;
 #define VFIO_DEVICE_FLAGS_RESET	(1 << 0)	/* Device supports reset */
 #define VFIO_DEVICE_FLAGS_PCI	(1 << 1)	/* vfio-pci device */
+#define VFIO_DEVICE_FLAGS_AER_NOTIFY (1 << 2)	/* Supports aer notify */
 	__u32	num_regions;	/* Max region index + 1 */
 	__u32	num_irqs;	/* Max IRQ index + 1 */
 };
@@ -288,6 +289,14 @@ struct vfio_irq_set {
  */
 #define VFIO_DEVICE_RESET		_IO(VFIO_TYPE, VFIO_BASE + 11)
 
+/**
+ * VFIO_DEVICE_SET_ERRFD - _IO(VFIO_TYPE, VFIO_BASE + 12)
+ *
+ * Pass the eventfd to the vfio-pci driver for signalling any device
+ * error notifications
+ */
+#define VFIO_DEVICE_SET_ERRFD		_IO(VFIO_TYPE, VFIO_BASE + 12)
+
 /*
  * The VFIO-PCI bus driver makes use of the following fixed region and
  * IRQ index mapping.  Unimplemented regions return a size of zero.
-- 
1.7.11.3

Re: [Qemu-devel] [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting AER

[Alex Williamson]

On Wed, 2013-01-09 at 06:26 +0000, Pandarathil, Vijaymohan R wrote:
> 	- New ioctl which is used to pass the eventfd that is signaled when
>           an error occurs in the vfio_pci_device
> 
> 	- Register pci_error_handler for the vfio_pci driver
> 
> 	- When the device encounters an error, the error handler registered by
>           the vfio_pci driver gets invoked by the AER infrastructure
> 
> 	- In the error handler, signal the eventfd registered for the device.
> 
> 	- This results in the qemu eventfd handler getting invoked and
>           appropriate action taken for the guest.
> 
> Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
> ---
>  drivers/vfio/pci/vfio_pci.c         | 29 +++++++++++++++++++++++++++++
>  drivers/vfio/pci/vfio_pci_private.h |  1 +
>  drivers/vfio/vfio.c                 |  8 ++++++++
>  include/linux/vfio.h                |  1 +
>  include/uapi/linux/vfio.h           |  9 +++++++++
>  5 files changed, 48 insertions(+)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 6c11994..4ae9526 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -207,6 +207,8 @@ static long vfio_pci_ioctl(void *device_data,
>  		if (vdev->reset_works)
>  			info.flags |= VFIO_DEVICE_FLAGS_RESET;
>  
> +		info.flags |= VFIO_DEVICE_FLAGS_AER_NOTIFY;
> +

This appears to be a PCI specific flag, so the name should include
_PCI_.  We also support non-PCIe devices and it seems like it would be
possible to not have AER support available, so shouldn't this be
conditional?

>  		info.num_regions = VFIO_PCI_NUM_REGIONS;
>  		info.num_irqs = VFIO_PCI_NUM_IRQS;
>  
> @@ -348,6 +350,19 @@ static long vfio_pci_ioctl(void *device_data,
>  
>  		return ret;
>  
> +	} else if (cmd == VFIO_DEVICE_SET_ERRFD) {
> +		int32_t fd = (int32_t)arg;
> +
> +		if (fd < 0)
> +			return -EINVAL;
> +
> +		vdev->err_trigger = eventfd_ctx_fdget(fd);
> +
> +		if (IS_ERR(vdev->err_trigger))
> +			return PTR_ERR(vdev->err_trigger);
> +
> +		return 0;
> +

I'm not sure why we wouldn't describe this as just another interrupt
from the device and configure it via SET_IRQ.  This ioctl has very
limited use and doesn't follow any of the conventions of all the other
vfio ioctls.

>  	} else if (cmd == VFIO_DEVICE_RESET)
>  		return vdev->reset_works ?
>  			pci_reset_function(vdev->pdev) : -EINVAL;
> @@ -527,11 +542,25 @@ static void vfio_pci_remove(struct pci_dev *pdev)
>  	kfree(vdev);
>  }
>  
> +static pci_ers_result_t vfio_err_detected(struct pci_dev *pdev,
> +				pci_channel_state_t state)
> +{
> +	struct vfio_pci_device *vdev = vfio_get_vdev(&pdev->dev);
> +
> +	eventfd_signal(vdev->err_trigger, 1);
> +	return PCI_ERS_RESULT_CAN_RECOVER;
> +}

What if err_trigger hasn't been set?

> +
> +static const struct pci_error_handlers vfio_err_handlers = {
> +	.error_detected = vfio_err_detected,
> +};
> +
>  static struct pci_driver vfio_pci_driver = {
>  	.name		= "vfio-pci",
>  	.id_table	= NULL, /* only dynamic ids */
>  	.probe		= vfio_pci_probe,
>  	.remove		= vfio_pci_remove,
> +	.err_handler	= &vfio_err_handlers,
>  };
>  
>  static void __exit vfio_pci_cleanup(void)
> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> index 611827c..daee62f 100644
> --- a/drivers/vfio/pci/vfio_pci_private.h
> +++ b/drivers/vfio/pci/vfio_pci_private.h
> @@ -55,6 +55,7 @@ struct vfio_pci_device {
>  	bool			bardirty;
>  	struct pci_saved_state	*pci_saved_state;
>  	atomic_t		refcnt;
> +	struct eventfd_ctx	*err_trigger;
>  };
>  
>  #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 56097c6..5ed5a54 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -693,6 +693,14 @@ void *vfio_del_group_dev(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(vfio_del_group_dev);
>  
> +void *vfio_get_vdev(struct device *dev)
> +{
> +	struct vfio_device *device = dev_get_drvdata(dev);
> +
> +	return device->device_data;
> +}
> +EXPORT_SYMBOL_GPL(vfio_get_vdev);
> +

This is unsafe.  How do we know dev is a vfio device?  How do we keep
that drvdata valid while you're using it?  I think you want to export
the existing vfio_group_get_device() and vfio_device_put().  Thanks,

Alex

>  /**
>   * VFIO base fd, /dev/vfio/vfio
>   */
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index ab9e862..3c97b03 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -45,6 +45,7 @@ extern int vfio_add_group_dev(struct device *dev,
>  			      void *device_data);
>  
>  extern void *vfio_del_group_dev(struct device *dev);
> +extern void *vfio_get_vdev(struct device *dev);
>  
>  /**
>   * struct vfio_iommu_driver_ops - VFIO IOMMU driver callbacks
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 4758d1b..fa67213 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -147,6 +147,7 @@ struct vfio_device_info {
>  	__u32	flags;
>  #define VFIO_DEVICE_FLAGS_RESET	(1 << 0)	/* Device supports reset */
>  #define VFIO_DEVICE_FLAGS_PCI	(1 << 1)	/* vfio-pci device */
> +#define VFIO_DEVICE_FLAGS_AER_NOTIFY (1 << 2)	/* Supports aer notify */
>  	__u32	num_regions;	/* Max region index + 1 */
>  	__u32	num_irqs;	/* Max IRQ index + 1 */
>  };
> @@ -288,6 +289,14 @@ struct vfio_irq_set {
>   */
>  #define VFIO_DEVICE_RESET		_IO(VFIO_TYPE, VFIO_BASE + 11)
>  
> +/**
> + * VFIO_DEVICE_SET_ERRFD - _IO(VFIO_TYPE, VFIO_BASE + 12)
> + *
> + * Pass the eventfd to the vfio-pci driver for signalling any device
> + * error notifications
> + */
> +#define VFIO_DEVICE_SET_ERRFD		_IO(VFIO_TYPE, VFIO_BASE + 12)
> +
>  /*
>   * The VFIO-PCI bus driver makes use of the following fixed region and
>   * IRQ index mapping.  Unimplemented regions return a size of zero.

Re: [Qemu-devel] [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting AER

[Pandarathil, Vijaymohan R]

> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@redhat.com]
> Sent: Wednesday, January 09, 2013 11:05 AM
> To: Pandarathil, Vijaymohan R
> Cc: Bjorn Helgaas; Gleb Natapov; kvm@vger.kernel.org; qemu-
> devel@nongnu.org; linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting
> AER
> 
> On Wed, 2013-01-09 at 10:52 -0700, Alex Williamson wrote:
> > On Wed, 2013-01-09 at 06:26 +0000, Pandarathil, Vijaymohan R wrote:
> > > 	- New ioctl which is used to pass the eventfd that is signaled when
> > >           an error occurs in the vfio_pci_device
> > >
> > > 	- Register pci_error_handler for the vfio_pci driver
> > >
> > > 	- When the device encounters an error, the error handler registered
> by
> > >           the vfio_pci driver gets invoked by the AER infrastructure
> > >
> > > 	- In the error handler, signal the eventfd registered for the device.
> > >
> > > 	- This results in the qemu eventfd handler getting invoked and
> > >           appropriate action taken for the guest.
> > >
> > > Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
> > > ---
> > >  drivers/vfio/pci/vfio_pci.c         | 29 +++++++++++++++++++++++++++++
> > >  drivers/vfio/pci/vfio_pci_private.h |  1 +
> > >  drivers/vfio/vfio.c                 |  8 ++++++++
> > >  include/linux/vfio.h                |  1 +
> > >  include/uapi/linux/vfio.h           |  9 +++++++++
> > >  5 files changed, 48 insertions(+)
> > >
> > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > > index 6c11994..4ae9526 100644
> > > --- a/drivers/vfio/pci/vfio_pci.c
> > > +++ b/drivers/vfio/pci/vfio_pci.c
> > > @@ -207,6 +207,8 @@ static long vfio_pci_ioctl(void *device_data,
> > >  		if (vdev->reset_works)
> > >  			info.flags |= VFIO_DEVICE_FLAGS_RESET;
> > >
> > > +		info.flags |= VFIO_DEVICE_FLAGS_AER_NOTIFY;
> > > +
> >
> > This appears to be a PCI specific flag, so the name should include
> > _PCI_.  We also support non-PCIe devices and it seems like it would be
> > possible to not have AER support available, so shouldn't this be
> > conditional?

Will do that.

> >
> > >  		info.num_regions = VFIO_PCI_NUM_REGIONS;
> > >  		info.num_irqs = VFIO_PCI_NUM_IRQS;
> > >
> > > @@ -348,6 +350,19 @@ static long vfio_pci_ioctl(void *device_data,
> > >
> > >  		return ret;
> > >
> > > +	} else if (cmd == VFIO_DEVICE_SET_ERRFD) {
> > > +		int32_t fd = (int32_t)arg;
> > > +
> > > +		if (fd < 0)
> > > +			return -EINVAL;
> > > +
> > > +		vdev->err_trigger = eventfd_ctx_fdget(fd);
> > > +
> > > +		if (IS_ERR(vdev->err_trigger))
> > > +			return PTR_ERR(vdev->err_trigger);
> > > +
> > > +		return 0;
> > > +
> >
> > I'm not sure why we wouldn't describe this as just another interrupt
> > from the device and configure it via SET_IRQ.  This ioctl has very
> > limited use and doesn't follow any of the conventions of all the other
> > vfio ioctls.

I thought this was a fairly simple ioctl to implement this way. Moreover, 
there is no device interrupt involved. Let me know if you really want to 
model it as a SET_IRQ ioctl.

> >
> > >  	} else if (cmd == VFIO_DEVICE_RESET)
> > >  		return vdev->reset_works ?
> > >  			pci_reset_function(vdev->pdev) : -EINVAL;
> > > @@ -527,11 +542,25 @@ static void vfio_pci_remove(struct pci_dev *pdev)
> > >  	kfree(vdev);
> > >  }
> > >
> > > +static pci_ers_result_t vfio_err_detected(struct pci_dev *pdev,
> > > +				pci_channel_state_t state)
> > > +{
> > > +	struct vfio_pci_device *vdev = vfio_get_vdev(&pdev->dev);
> > > +
> > > +	eventfd_signal(vdev->err_trigger, 1);
> > > +	return PCI_ERS_RESULT_CAN_RECOVER;
> > > +}
> >
> > What if err_trigger hasn't been set?

Will fix that.

> >
> > > +
> > > +static const struct pci_error_handlers vfio_err_handlers = {
> > > +	.error_detected = vfio_err_detected,
> > > +};
> > > +
> > >  static struct pci_driver vfio_pci_driver = {
> > >  	.name		= "vfio-pci",
> > >  	.id_table	= NULL, /* only dynamic ids */
> > >  	.probe		= vfio_pci_probe,
> > >  	.remove		= vfio_pci_remove,
> > > +	.err_handler	= &vfio_err_handlers,
> > >  };
> > >
> > >  static void __exit vfio_pci_cleanup(void)
> > > diff --git a/drivers/vfio/pci/vfio_pci_private.h
> b/drivers/vfio/pci/vfio_pci_private.h
> > > index 611827c..daee62f 100644
> > > --- a/drivers/vfio/pci/vfio_pci_private.h
> > > +++ b/drivers/vfio/pci/vfio_pci_private.h
> > > @@ -55,6 +55,7 @@ struct vfio_pci_device {
> > >  	bool			bardirty;
> > >  	struct pci_saved_state	*pci_saved_state;
> > >  	atomic_t		refcnt;
> > > +	struct eventfd_ctx	*err_trigger;
> > >  };
> > >
> > >  #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
> > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> > > index 56097c6..5ed5a54 100644
> > > --- a/drivers/vfio/vfio.c
> > > +++ b/drivers/vfio/vfio.c
> > > @@ -693,6 +693,14 @@ void *vfio_del_group_dev(struct device *dev)
> > >  }
> > >  EXPORT_SYMBOL_GPL(vfio_del_group_dev);
> > >
> > > +void *vfio_get_vdev(struct device *dev)
> > > +{
> > > +	struct vfio_device *device = dev_get_drvdata(dev);
> > > +
> > > +	return device->device_data;
> > > +}
> > > +EXPORT_SYMBOL_GPL(vfio_get_vdev);
> > > +
> >
> > This is unsafe.  How do we know dev is a vfio device?  How do we keep
> > that drvdata valid while you're using it?  I think you want to export
> > the existing vfio_group_get_device() and vfio_device_put().  Thanks,
> 
> vfio_group_get_device() isn't quite what you want either since it
> assumes a reference count on the group.  You'll want something like
> vfio_add_group_dev() or vfio_dev_present(), perhaps moving the
> iommu_group_get -> vfio_group_get_from_iommu -> vfio_group_get_device
> into a helper function.  Thanks,

Thanks for the pointers. Will make the change.

Vijay

> 
> Alex
> 
> > >  /**
> > >   * VFIO base fd, /dev/vfio/vfio
> > >   */
> > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > > index ab9e862..3c97b03 100644
> > > --- a/include/linux/vfio.h
> > > +++ b/include/linux/vfio.h
> > > @@ -45,6 +45,7 @@ extern int vfio_add_group_dev(struct device *dev,
> > >  			      void *device_data);
> > >
> > >  extern void *vfio_del_group_dev(struct device *dev);
> > > +extern void *vfio_get_vdev(struct device *dev);
> > >
> > >  /**
> > >   * struct vfio_iommu_driver_ops - VFIO IOMMU driver callbacks
> > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> > > index 4758d1b..fa67213 100644
> > > --- a/include/uapi/linux/vfio.h
> > > +++ b/include/uapi/linux/vfio.h
> > > @@ -147,6 +147,7 @@ struct vfio_device_info {
> > >  	__u32	flags;
> > >  #define VFIO_DEVICE_FLAGS_RESET	(1 << 0)	/* Device supports
> reset */
> > >  #define VFIO_DEVICE_FLAGS_PCI	(1 << 1)	/* vfio-pci device */
> > > +#define VFIO_DEVICE_FLAGS_AER_NOTIFY (1 << 2)	/* Supports aer
> notify */
> > >  	__u32	num_regions;	/* Max region index + 1 */
> > >  	__u32	num_irqs;	/* Max IRQ index + 1 */
> > >  };
> > > @@ -288,6 +289,14 @@ struct vfio_irq_set {
> > >   */
> > >  #define VFIO_DEVICE_RESET		_IO(VFIO_TYPE, VFIO_BASE + 11)
> > >
> > > +/**
> > > + * VFIO_DEVICE_SET_ERRFD - _IO(VFIO_TYPE, VFIO_BASE + 12)
> > > + *
> > > + * Pass the eventfd to the vfio-pci driver for signalling any device
> > > + * error notifications
> > > + */
> > > +#define VFIO_DEVICE_SET_ERRFD		_IO(VFIO_TYPE, VFIO_BASE + 12)
> > > +
> > >  /*
> > >   * The VFIO-PCI bus driver makes use of the following fixed region and
> > >   * IRQ index mapping.  Unimplemented regions return a size of zero.
> >
> >
> 
> 

Re: [Qemu-devel] [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting AER

[Alex Williamson]

On Fri, 2013-01-11 at 08:45 +0000, Pandarathil, Vijaymohan R wrote:
> 
> > -----Original Message-----
> > From: Alex Williamson [mailto:alex.williamson@redhat.com]
> > Sent: Wednesday, January 09, 2013 11:05 AM
> > To: Pandarathil, Vijaymohan R
> > Cc: Bjorn Helgaas; Gleb Natapov; kvm@vger.kernel.org; qemu-
> > devel@nongnu.org; linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org
> > Subject: Re: [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting
> > AER
> > 
> > On Wed, 2013-01-09 at 10:52 -0700, Alex Williamson wrote:
> > > On Wed, 2013-01-09 at 06:26 +0000, Pandarathil, Vijaymohan R wrote:
> > > > 	- New ioctl which is used to pass the eventfd that is signaled when
> > > >           an error occurs in the vfio_pci_device
> > > >
> > > > 	- Register pci_error_handler for the vfio_pci driver
> > > >
> > > > 	- When the device encounters an error, the error handler registered
> > by
> > > >           the vfio_pci driver gets invoked by the AER infrastructure
> > > >
> > > > 	- In the error handler, signal the eventfd registered for the device.
> > > >
> > > > 	- This results in the qemu eventfd handler getting invoked and
> > > >           appropriate action taken for the guest.
> > > >
> > > > Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
> > > > ---
> > > >  drivers/vfio/pci/vfio_pci.c         | 29 +++++++++++++++++++++++++++++
> > > >  drivers/vfio/pci/vfio_pci_private.h |  1 +
> > > >  drivers/vfio/vfio.c                 |  8 ++++++++
> > > >  include/linux/vfio.h                |  1 +
> > > >  include/uapi/linux/vfio.h           |  9 +++++++++
> > > >  5 files changed, 48 insertions(+)
> > > >
> > > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > > > index 6c11994..4ae9526 100644
> > > > --- a/drivers/vfio/pci/vfio_pci.c
> > > > +++ b/drivers/vfio/pci/vfio_pci.c
> > > > @@ -207,6 +207,8 @@ static long vfio_pci_ioctl(void *device_data,
> > > >  		if (vdev->reset_works)
> > > >  			info.flags |= VFIO_DEVICE_FLAGS_RESET;
> > > >
> > > > +		info.flags |= VFIO_DEVICE_FLAGS_AER_NOTIFY;
> > > > +
> > >
> > > This appears to be a PCI specific flag, so the name should include
> > > _PCI_.  We also support non-PCIe devices and it seems like it would be
> > > possible to not have AER support available, so shouldn't this be
> > > conditional?
> 
> Will do that.
> 
> > >
> > > >  		info.num_regions = VFIO_PCI_NUM_REGIONS;
> > > >  		info.num_irqs = VFIO_PCI_NUM_IRQS;
> > > >
> > > > @@ -348,6 +350,19 @@ static long vfio_pci_ioctl(void *device_data,
> > > >
> > > >  		return ret;
> > > >
> > > > +	} else if (cmd == VFIO_DEVICE_SET_ERRFD) {
> > > > +		int32_t fd = (int32_t)arg;
> > > > +
> > > > +		if (fd < 0)
> > > > +			return -EINVAL;
> > > > +
> > > > +		vdev->err_trigger = eventfd_ctx_fdget(fd);
> > > > +
> > > > +		if (IS_ERR(vdev->err_trigger))
> > > > +			return PTR_ERR(vdev->err_trigger);
> > > > +
> > > > +		return 0;
> > > > +
> > >
> > > I'm not sure why we wouldn't describe this as just another interrupt
> > > from the device and configure it via SET_IRQ.  This ioctl has very
> > > limited use and doesn't follow any of the conventions of all the other
> > > vfio ioctls.
> 
> I thought this was a fairly simple ioctl to implement this way. Moreover, 
> there is no device interrupt involved. Let me know if you really want to 
> model it as a SET_IRQ ioctl.

I'd like to see something else for sure.  We're trying to do AER
piecemeal but this ioctl leaves no room for anything else.  Seems like a
soon to be wasted ioctl number.  Note that there isn't even a de-assign
interface, nor a flag to set to indicate de-assignment.  The SET_IRQ
ioctl already handles these in a very similar way to how we'd want to
handle it for error signaling.  It doesn't seem like that much of a
stretch to me to include it there, but I'd also entertain other ideas.
Thanks,

Alex

> > >
> > > >  	} else if (cmd == VFIO_DEVICE_RESET)
> > > >  		return vdev->reset_works ?
> > > >  			pci_reset_function(vdev->pdev) : -EINVAL;
> > > > @@ -527,11 +542,25 @@ static void vfio_pci_remove(struct pci_dev *pdev)
> > > >  	kfree(vdev);
> > > >  }
> > > >
> > > > +static pci_ers_result_t vfio_err_detected(struct pci_dev *pdev,
> > > > +				pci_channel_state_t state)
> > > > +{
> > > > +	struct vfio_pci_device *vdev = vfio_get_vdev(&pdev->dev);
> > > > +
> > > > +	eventfd_signal(vdev->err_trigger, 1);
> > > > +	return PCI_ERS_RESULT_CAN_RECOVER;
> > > > +}
> > >
> > > What if err_trigger hasn't been set?
> 
> Will fix that.
> 
> > >
> > > > +
> > > > +static const struct pci_error_handlers vfio_err_handlers = {
> > > > +	.error_detected = vfio_err_detected,
> > > > +};
> > > > +
> > > >  static struct pci_driver vfio_pci_driver = {
> > > >  	.name		= "vfio-pci",
> > > >  	.id_table	= NULL, /* only dynamic ids */
> > > >  	.probe		= vfio_pci_probe,
> > > >  	.remove		= vfio_pci_remove,
> > > > +	.err_handler	= &vfio_err_handlers,
> > > >  };
> > > >
> > > >  static void __exit vfio_pci_cleanup(void)
> > > > diff --git a/drivers/vfio/pci/vfio_pci_private.h
> > b/drivers/vfio/pci/vfio_pci_private.h
> > > > index 611827c..daee62f 100644
> > > > --- a/drivers/vfio/pci/vfio_pci_private.h
> > > > +++ b/drivers/vfio/pci/vfio_pci_private.h
> > > > @@ -55,6 +55,7 @@ struct vfio_pci_device {
> > > >  	bool			bardirty;
> > > >  	struct pci_saved_state	*pci_saved_state;
> > > >  	atomic_t		refcnt;
> > > > +	struct eventfd_ctx	*err_trigger;
> > > >  };
> > > >
> > > >  #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
> > > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> > > > index 56097c6..5ed5a54 100644
> > > > --- a/drivers/vfio/vfio.c
> > > > +++ b/drivers/vfio/vfio.c
> > > > @@ -693,6 +693,14 @@ void *vfio_del_group_dev(struct device *dev)
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(vfio_del_group_dev);
> > > >
> > > > +void *vfio_get_vdev(struct device *dev)
> > > > +{
> > > > +	struct vfio_device *device = dev_get_drvdata(dev);
> > > > +
> > > > +	return device->device_data;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(vfio_get_vdev);
> > > > +
> > >
> > > This is unsafe.  How do we know dev is a vfio device?  How do we keep
> > > that drvdata valid while you're using it?  I think you want to export
> > > the existing vfio_group_get_device() and vfio_device_put().  Thanks,
> > 
> > vfio_group_get_device() isn't quite what you want either since it
> > assumes a reference count on the group.  You'll want something like
> > vfio_add_group_dev() or vfio_dev_present(), perhaps moving the
> > iommu_group_get -> vfio_group_get_from_iommu -> vfio_group_get_device
> > into a helper function.  Thanks,
> 
> Thanks for the pointers. Will make the change.
> 
> Vijay
> 
> > 
> > Alex
> > 
> > > >  /**
> > > >   * VFIO base fd, /dev/vfio/vfio
> > > >   */
> > > > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > > > index ab9e862..3c97b03 100644
> > > > --- a/include/linux/vfio.h
> > > > +++ b/include/linux/vfio.h
> > > > @@ -45,6 +45,7 @@ extern int vfio_add_group_dev(struct device *dev,
> > > >  			      void *device_data);
> > > >
> > > >  extern void *vfio_del_group_dev(struct device *dev);
> > > > +extern void *vfio_get_vdev(struct device *dev);
> > > >
> > > >  /**
> > > >   * struct vfio_iommu_driver_ops - VFIO IOMMU driver callbacks
> > > > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> > > > index 4758d1b..fa67213 100644
> > > > --- a/include/uapi/linux/vfio.h
> > > > +++ b/include/uapi/linux/vfio.h
> > > > @@ -147,6 +147,7 @@ struct vfio_device_info {
> > > >  	__u32	flags;
> > > >  #define VFIO_DEVICE_FLAGS_RESET	(1 << 0)	/* Device supports
> > reset */
> > > >  #define VFIO_DEVICE_FLAGS_PCI	(1 << 1)	/* vfio-pci device */
> > > > +#define VFIO_DEVICE_FLAGS_AER_NOTIFY (1 << 2)	/* Supports aer
> > notify */
> > > >  	__u32	num_regions;	/* Max region index + 1 */
> > > >  	__u32	num_irqs;	/* Max IRQ index + 1 */
> > > >  };
> > > > @@ -288,6 +289,14 @@ struct vfio_irq_set {
> > > >   */
> > > >  #define VFIO_DEVICE_RESET		_IO(VFIO_TYPE, VFIO_BASE + 11)
> > > >
> > > > +/**
> > > > + * VFIO_DEVICE_SET_ERRFD - _IO(VFIO_TYPE, VFIO_BASE + 12)
> > > > + *
> > > > + * Pass the eventfd to the vfio-pci driver for signalling any device
> > > > + * error notifications
> > > > + */
> > > > +#define VFIO_DEVICE_SET_ERRFD		_IO(VFIO_TYPE, VFIO_BASE + 12)
> > > > +
> > > >  /*
> > > >   * The VFIO-PCI bus driver makes use of the following fixed region and
> > > >   * IRQ index mapping.  Unimplemented regions return a size of zero.
> > >
> > >
> > 
> > 
> 

Re: [Qemu-devel] [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting AER

[Marcelo Tosatti]

On Fri, Jan 11, 2013 at 08:46:35AM -0700, Alex Williamson wrote:
> On Fri, 2013-01-11 at 08:45 +0000, Pandarathil, Vijaymohan R wrote:
> > 
> > > -----Original Message-----
> > > From: Alex Williamson [mailto:alex.williamson@redhat.com]
> > > Sent: Wednesday, January 09, 2013 11:05 AM
> > > To: Pandarathil, Vijaymohan R
> > > Cc: Bjorn Helgaas; Gleb Natapov; kvm@vger.kernel.org; qemu-
> > > devel@nongnu.org; linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting
> > > AER
> > > 
> > > On Wed, 2013-01-09 at 10:52 -0700, Alex Williamson wrote:
> > > > On Wed, 2013-01-09 at 06:26 +0000, Pandarathil, Vijaymohan R wrote:
> > > > > 	- New ioctl which is used to pass the eventfd that is signaled when
> > > > >           an error occurs in the vfio_pci_device
> > > > >
> > > > > 	- Register pci_error_handler for the vfio_pci driver
> > > > >
> > > > > 	- When the device encounters an error, the error handler registered
> > > by
> > > > >           the vfio_pci driver gets invoked by the AER infrastructure
> > > > >
> > > > > 	- In the error handler, signal the eventfd registered for the device.
> > > > >
> > > > > 	- This results in the qemu eventfd handler getting invoked and
> > > > >           appropriate action taken for the guest.
> > > > >
> > > > > Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
> > > > > ---
> > > > >  drivers/vfio/pci/vfio_pci.c         | 29 +++++++++++++++++++++++++++++
> > > > >  drivers/vfio/pci/vfio_pci_private.h |  1 +
> > > > >  drivers/vfio/vfio.c                 |  8 ++++++++
> > > > >  include/linux/vfio.h                |  1 +
> > > > >  include/uapi/linux/vfio.h           |  9 +++++++++
> > > > >  5 files changed, 48 insertions(+)
> > > > >
> > > > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > > > > index 6c11994..4ae9526 100644
> > > > > --- a/drivers/vfio/pci/vfio_pci.c
> > > > > +++ b/drivers/vfio/pci/vfio_pci.c
> > > > > @@ -207,6 +207,8 @@ static long vfio_pci_ioctl(void *device_data,
> > > > >  		if (vdev->reset_works)
> > > > >  			info.flags |= VFIO_DEVICE_FLAGS_RESET;
> > > > >
> > > > > +		info.flags |= VFIO_DEVICE_FLAGS_AER_NOTIFY;
> > > > > +
> > > >
> > > > This appears to be a PCI specific flag, so the name should include
> > > > _PCI_.  We also support non-PCIe devices and it seems like it would be
> > > > possible to not have AER support available, so shouldn't this be
> > > > conditional?
> > 
> > Will do that.
> > 
> > > >
> > > > >  		info.num_regions = VFIO_PCI_NUM_REGIONS;
> > > > >  		info.num_irqs = VFIO_PCI_NUM_IRQS;
> > > > >
> > > > > @@ -348,6 +350,19 @@ static long vfio_pci_ioctl(void *device_data,
> > > > >
> > > > >  		return ret;
> > > > >
> > > > > +	} else if (cmd == VFIO_DEVICE_SET_ERRFD) {
> > > > > +		int32_t fd = (int32_t)arg;
> > > > > +
> > > > > +		if (fd < 0)
> > > > > +			return -EINVAL;
> > > > > +
> > > > > +		vdev->err_trigger = eventfd_ctx_fdget(fd);
> > > > > +
> > > > > +		if (IS_ERR(vdev->err_trigger))
> > > > > +			return PTR_ERR(vdev->err_trigger);
> > > > > +
> > > > > +		return 0;
> > > > > +
> > > >
> > > > I'm not sure why we wouldn't describe this as just another interrupt
> > > > from the device and configure it via SET_IRQ.  This ioctl has very
> > > > limited use and doesn't follow any of the conventions of all the other
> > > > vfio ioctls.
> > 
> > I thought this was a fairly simple ioctl to implement this way. Moreover, 
> > there is no device interrupt involved. Let me know if you really want to 
> > model it as a SET_IRQ ioctl.
> 
> I'd like to see something else for sure.  We're trying to do AER
> piecemeal but this ioctl leaves no room for anything else.  Seems like a
> soon to be wasted ioctl number.  Note that there isn't even a de-assign
> interface, nor a flag to set to indicate de-assignment.  The SET_IRQ
> ioctl already handles these in a very similar way to how we'd want to
> handle it for error signaling.  It doesn't seem like that much of a
> stretch to me to include it there, but I'd also entertain other ideas.
> Thanks,
> 
> Alex

Yes it would be good to have a picture of the dependencies necessary to
implement passthrough, before introducing an incompatible interface.