Re: [PATCH 2/2] QEMU-AER: Qemu changes to support AER for VFIO-PCIdevices

[Alex Williamson]

On Wed, 2013-01-09 at 06:26 +0000, Pandarathil, Vijaymohan R wrote:
> 	- Create eventfd per vfio device assigned to a guest and register an
>           event handler
> 
> 	- This fd is passed to the vfio_pci driver through a new ioctl
> 
> 	- When the device encounters an error, the eventfd is signaled
>           and the qemu eventfd handler gets invoked.
> 
> 	- In the handler decide what action to take. Current action taken
>           is to terminate the guest.
> 
> Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@xxxxxx>
> ---
>  hw/vfio_pci.c              | 56 ++++++++++++++++++++++++++++++++++++++++++++++
>  linux-headers/linux/vfio.h |  9 ++++++++
>  2 files changed, 65 insertions(+)
> 
> diff --git a/hw/vfio_pci.c b/hw/vfio_pci.c
> index 28c8303..9c3c28b 100644
> --- a/hw/vfio_pci.c
> +++ b/hw/vfio_pci.c
> @@ -38,6 +38,7 @@
>  #include "qemu/error-report.h"
>  #include "qemu/queue.h"
>  #include "qemu/range.h"
> +#include "sysemu/sysemu.h"
>  
>  /* #define DEBUG_VFIO */
>  #ifdef DEBUG_VFIO
> @@ -130,6 +131,8 @@ typedef struct VFIODevice {
>      QLIST_ENTRY(VFIODevice) next;
>      struct VFIOGroup *group;
>      bool reset_works;
> +    EventNotifier errfd;

Misleading name, it's an EventNotifier not an fd.

> +    __u32 dev_info_flags;
>  } VFIODevice;
>  
>  typedef struct VFIOGroup {
> @@ -1805,6 +1808,8 @@ static int vfio_get_device(VFIOGroup *group, const char *name, VFIODevice *vdev)
>      DPRINTF("Device %s flags: %u, regions: %u, irgs: %u\n", name,
>              dev_info.flags, dev_info.num_regions, dev_info.num_irqs);
>  
> +    vdev->dev_info_flags = dev_info.flags;
> +

We test the VFIO_DEVICE_FLAGS_RESET elsewhere by caching the bit into a
variable, why not do that here too?

>      if (!(dev_info.flags & VFIO_DEVICE_FLAGS_PCI)) {
>          error_report("vfio: Um, this isn't a PCI device\n");
>          goto error;
> @@ -1900,6 +1905,55 @@ static void vfio_put_device(VFIODevice *vdev)
>      }
>  }
>  
> +static void vfio_errfd_handler(void *opaque)
> +{
> +    VFIODevice *vdev = opaque;
> +
> +    if (!event_notifier_test_and_clear(&vdev->errfd)) {
> +        return;
> +    }
> +
> +    /*
> +     * TBD. Retrieve the error details and decide what action
> +     * needs to be taken. One of the actions could be to pass
> +     * the error to the guest and have the guest driver recover
> +     * the error. This requires that PCIe capabilities be
> +     * exposed to the guest. At present, we just terminate the
> +     * guest to contain the error.
> +     */
> +    error_report("%s(%04x:%02x:%02x.%x) "
> +        "Unrecoverable error detected... Terminating guest\n",
> +        __func__, vdev->host.domain, vdev->host.bus, vdev->host.slot,
> +        vdev->host.function);
> +
> +    qemu_system_shutdown_request();

I would have figured hw_error

> +    return;
> +}
> +
> +static void vfio_register_errfd(VFIODevice *vdev)
> +{
> +    int32_t pfd;

"pfd" is used elsewhere in vfio as "Pointer to FD", this is just a fd.

> +    int ret;
> +
> +    if (!(vdev->dev_info_flags & VFIO_DEVICE_FLAGS_AER_NOTIFY)) {
> +        error_report("vfio: Warning: Error notification not supported for the device\n");

This should probably just be a debug print.

> +        return;
> +    }
> +    if (event_notifier_init(&vdev->errfd, 0)) {
> +        error_report("vfio: Warning: Unable to init event notifier for error detection\n");
> +        return;
> +    }
> +    pfd = event_notifier_get_fd(&vdev->errfd);
> +    qemu_set_fd_handler(pfd, vfio_errfd_handler, NULL, vdev);
> +
> +    ret = ioctl(vdev->fd, VFIO_DEVICE_SET_ERRFD, pfd);
> +    if (ret) {
> +        error_report("vfio: Warning: Failed to setup error fd: %d\n", ret);
> +        qemu_set_fd_handler(pfd, NULL, NULL, vdev);
> +        event_notifier_cleanup(&vdev->errfd);
> +    }
> +    return;
> +}
>  static int vfio_initfn(PCIDevice *pdev)
>  {
>      VFIODevice *pvdev, *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
> @@ -2010,6 +2064,8 @@ static int vfio_initfn(PCIDevice *pdev)
>          }
>      }
>  
> +    vfio_register_errfd(vdev);
> +

No cleanup in exitfn?!  Thanks,

Alex

>      return 0;
>  
>  out_teardown:
> diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
> index 4758d1b..0ca4eeb 100644
> --- a/linux-headers/linux/vfio.h
> +++ b/linux-headers/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 notification */
>  	__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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