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Date: Wed, 09 Jan 2013 10:52:33 -0700
From: Alex Williamson <alex.williamson@...hat.com>
To: "Pandarathil, Vijaymohan R" <vijaymohan.pandarathil@...com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Gleb Natapov <gleb@...hat.com>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"qemu-devel@...gnu.org" <qemu-devel@...gnu.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] VFIO-AER: Vfio-pci driver changes for supporting AER
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@...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.
--
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