Re: [Qemu-devel] [PATCH v2 05/11] vfio: add check host bus reset is support or not

[Alex Williamson]

On Mon, 7 Mar 2016 11:22:58 +0800
Cao jin <address@hidden> wrote:

> From: Chen Fan <address@hidden>
> 
> when boot up a VM that assigning vfio devices with aer enabled, we
> must check the vfio device whether support host bus reset. because
> when one error occur. OS driver always recover the device by do a
> bus reset, in order to recover the vfio device, qemu must to do a
> host bus reset to reset the device to default status. and for all
> affected devices by the bus reset. we must check them whether all
> are assigned to the VM.
> 
> Signed-off-by: Chen Fan <address@hidden>
> ---
>  hw/vfio/pci.c | 218 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  hw/vfio/pci.h |   1 +
>  2 files changed, 212 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 8ec9b25..0898e34 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1868,6 +1868,197 @@ static int vfio_add_std_cap(VFIOPCIDevice *vdev, 
> uint8_t pos)
>      return 0;
>  }
>  
> +static bool vfio_pci_host_slot_match(PCIHostDeviceAddress *host1,
> +                                     PCIHostDeviceAddress *host2)
> +{
> +    return (host1->domain == host2->domain && host1->bus == host2->bus &&
> +            host1->slot == host2->slot);
> +}
> +
> +static bool vfio_pci_host_match(PCIHostDeviceAddress *host1,
> +                                PCIHostDeviceAddress *host2)
> +{
> +    return (vfio_pci_host_slot_match(host1, host2) &&
> +            host1->function == host2->function);
> +}
> +
> +struct VFIODeviceFind {
> +    PCIDevice *pdev;
> +    bool found;
> +};
> +
> +static void vfio_check_device_noreset(PCIBus *bus, PCIDevice *pdev,
> +                                      void *opaque)
> +{
> +    DeviceState *dev = DEVICE(pdev);
> +    DeviceClass *dc = DEVICE_GET_CLASS(dev);
> +    VFIOPCIDevice *vdev;
> +    struct VFIODeviceFind *find = opaque;
> +
> +    if (find->found) {
> +        return;
> +    }
> +
> +    if (!object_dynamic_cast(OBJECT(dev), "vfio-pci")) {
> +        if (!dc->reset) {
> +            goto found;
> +        }
> +        return;
> +    }
> +    vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
> +    if (!(vdev->features & VFIO_FEATURE_ENABLE_AER) &&
> +        !vdev->vbasedev.reset_works) {
> +        goto found;
> +    }
> +
> +    return;
> +found:
> +    find->pdev = pdev;
> +    find->found = true;
> +}
> +
> +static void vfio_check_host_bus_reset(VFIOPCIDevice *vdev, Error **errp)
> +{
> +    PCIBus *bus = vdev->pdev.bus;
> +    struct vfio_pci_hot_reset_info *info = NULL;
> +    struct vfio_pci_dependent_device *devices;
> +    VFIOGroup *group;
> +    struct VFIODeviceFind find;
> +    int ret, i;
> +
> +    ret = vfio_get_hot_reset_info(vdev, &info);
> +    if (ret) {
> +        error_setg(errp, "vfio: Cannot enable AER for device %s,"
> +                   " device does not support hot reset.",
> +                   vdev->vbasedev.name);
> +        return;
> +    }
> +
> +    /* List all affected devices by bus reset */
> +    devices = &info->devices[0];
> +
> +    /* Verify that we have all the groups required */
> +    for (i = 0; i < info->count; i++) {
> +        PCIHostDeviceAddress host;
> +        VFIOPCIDevice *tmp;
> +        VFIODevice *vbasedev_iter;
> +        bool found = false;
> +
> +        host.domain = devices[i].segment;
> +        host.bus = devices[i].bus;
> +        host.slot = PCI_SLOT(devices[i].devfn);
> +        host.function = PCI_FUNC(devices[i].devfn);
> +
> +        /* Skip the current device */
> +        if (vfio_pci_host_match(&host, &vdev->host)) {
> +            continue;
> +        }
> +
> +        /* Ensure we own the group of the affected device */
> +        QLIST_FOREACH(group, &vfio_group_list, next) {
> +            if (group->groupid == devices[i].group_id) {
> +                break;
> +            }
> +        }
> +
> +        if (!group) {
> +            error_setg(errp, "vfio: Cannot enable AER for device %s, "
> +                       "depends on group %d which is not owned.",
> +                       vdev->vbasedev.name, devices[i].group_id);
> +            goto out;
> +        }
> +
> +        /* Ensure affected devices for reset on the same slot */
> +        QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
> +            if (vbasedev_iter->type != VFIO_DEVICE_TYPE_PCI) {
> +                continue;
> +            }
> +            tmp = container_of(vbasedev_iter, VFIOPCIDevice, vbasedev);
> +            if (vfio_pci_host_match(&host, &tmp->host)) {
> +                /*
> +                 * AER errors may be broadcast to all functions of a multi-
> +                 * function endpoint.  If any of those sibling functions are
> +                 * also assigned, they need to have AER enabled or else an
> +                 * error may continue to cause a vm_stop condition.  IOW,
> +                 * AER setup of this function would be pointless.
> +                 */
> +                if (vfio_pci_host_slot_match(&vdev->host, &tmp->host) &&
> +                    !(tmp->features & VFIO_FEATURE_ENABLE_AER)) {
> +                    error_setg(errp, "vfio: Cannot enable AER for device %s, 
> on same slot"
> +                               " the dependent device %s which does not 
> enable AER.",
> +                               vdev->vbasedev.name, tmp->vbasedev.name);
> +                    goto out;
> +                }
> +
> +                if (tmp->pdev.bus != bus) {
> +                    error_setg(errp, "vfio: Cannot enable AER for device %s, 
> "
> +                               "the dependent device %s is not on the same 
> bus",
> +                               vdev->vbasedev.name, tmp->vbasedev.name);
> +                    goto out;
> +                }
> +                found = true;
> +                break;
> +            }
> +        }
> +
> +        /* Ensure all affected devices assigned to VM */
> +        if (!found) {
> +            error_setg(errp, "vfio: Cannot enable AER for device %s, "
> +                       "the dependent device %04x:%02x:%02x.%x "
> +                       "is not assigned to VM.",
> +                       vdev->vbasedev.name, host.domain, host.bus,
> +                       host.slot, host.function);
> +            goto out;
> +        }
> +    }
> +
> +    /*
> +     * Check the all pci devices on or below the target bus
> +     * have a reset mechanism at least.
> +     */
> +    find.pdev = NULL;
> +    find.found = false;
> +    pci_for_each_device(bus, pci_bus_num(bus),

I'm not fully convinced this does what it says that it does.  Bus
numbers are under guest control, but using pci_bus_num(bus) here will
cause us to always take the path in pci_find_bus_nr() where it simply
returns bus.  Thus we call pci_for_each_device_under_bus() with the bus
originally provided in pci_for_each_device().  But
pci_for_each_device_under_bus() only iterates the devfns immediately on
that bus, despite the name that would imply otherwise.  So it seems
like the pci_for_each_device() callback would need to itself call
pci_for_each_device() if it finds a bridge.  Am I missing something or
is that correct?

We could also just go on to require that there are no subordinate buses
to this bus, which seems like a reasonable thing to do.  Thanks,

Alex

> +                        vfio_check_device_noreset, &find);
> +    if (find.found) {
> +        error_setg(errp, "vfio: Cannot enable AER for device %s, "
> +                   "the affected device %s does not have a reset mechanism.",
> +                   vdev->vbasedev.name, find.pdev->name);
> +        goto out;
> +    }
> +
> +out:
> +    g_free(info);
> +    return;
> +}
> +
> +static void vfio_check_devices_host_bus_reset(Error **errp)
> +{
> +    VFIOGroup *group;
> +    VFIODevice *vbasedev;
> +    VFIOPCIDevice *vdev;
> +    Error *local_err = NULL;
> +
> +    /* Check All vfio-pci devices if have bus reset capability */
> +    QLIST_FOREACH(group, &vfio_group_list, next) {
> +        QLIST_FOREACH(vbasedev, &group->device_list, next) {
> +            if (vbasedev->type != VFIO_DEVICE_TYPE_PCI) {
> +                continue;
> +            }
> +            vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
> +            if (vdev->features & VFIO_FEATURE_ENABLE_AER) {
> +                vfio_check_host_bus_reset(vdev, &local_err);
> +                if (local_err) {
> +                    error_propagate(errp, local_err);
> +                    return;
> +                }
> +            }
> +        }
> +    }
> +
> +    return;
> +}
> +
>  static int vfio_setup_aer(VFIOPCIDevice *vdev, uint8_t cap_ver,
>                            int pos, uint16_t size)
>  {
> @@ -2047,13 +2238,6 @@ static void vfio_pci_post_reset(VFIOPCIDevice *vdev)
>      vfio_intx_enable(vdev);
>  }
>  
> -static bool vfio_pci_host_match(PCIHostDeviceAddress *host1,
> -                                PCIHostDeviceAddress *host2)
> -{
> -    return (host1->domain == host2->domain && host1->bus == host2->bus &&
> -            host1->slot == host2->slot && host1->function == 
> host2->function);
> -}
> -
>  static int vfio_pci_hot_reset(VFIOPCIDevice *vdev, bool single)
>  {
>      VFIOGroup *group;
> @@ -2559,6 +2743,21 @@ static void vfio_unregister_req_notifier(VFIOPCIDevice 
> *vdev)
>      vdev->req_enabled = false;
>  }
>  
> +static void vfio_pci_machine_done_notify(Notifier *notifier, void *unused)
> +{
> +    Error *local_err = NULL;
> +
> +    vfio_check_devices_host_bus_reset(&local_err);
> +    if (local_err) {
> +        error_report_err(local_err);
> +        exit(1);
> +    }
> +}
> +
> +static Notifier machine_notifier = {
> +    .notify = vfio_pci_machine_done_notify,
> +};
> +
>  static int vfio_initfn(PCIDevice *pdev)
>  {
>      VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
> @@ -2905,6 +3104,11 @@ static const TypeInfo vfio_pci_dev_info = {
>  static void register_vfio_pci_dev_type(void)
>  {
>      type_register_static(&vfio_pci_dev_info);
> +    /*
> +     * Register notifier when machine init is done, since we need
> +     * check the configration manner after all vfio device are inited.
> +     */
> +    qemu_add_machine_init_done_notifier(&machine_notifier);
>  }
>  
>  type_init(register_vfio_pci_dev_type)
> diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
> index e0c53f2..aff46c2 100644
> --- a/hw/vfio/pci.h
> +++ b/hw/vfio/pci.h
> @@ -15,6 +15,7 @@
>  #include "qemu-common.h"
>  #include "exec/memory.h"
>  #include "hw/pci/pci.h"
> +#include "hw/pci/pci_bus.h"
>  #include "hw/pci/pci_bridge.h"
>  #include "hw/vfio/vfio-common.h"
>  #include "qemu/event_notifier.h"