Re: [PATCH v5 02/11] pci: add option for net failover

[Alex Williamson <alex.williamson@redhat.com>]

On Wed, 23 Oct 2019 10:27:02 +0200
Jens Freimann <jfreimann@redhat.com> wrote:

> This patch adds a net_failover_pair_id property to PCIDev which is
> used to link the primary device in a failover pair (the PCI dev) to
> a standby (a virtio-net-pci) device.
> 
> It only supports ethernet devices. Also currently it only supports
> PCIe devices. QEMU will exit with an error message otherwise.
> 
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>
> ---
>  hw/pci/pci.c         | 17 +++++++++++++++++
>  include/hw/pci/pci.h |  3 +++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index aa05c2b9b2..fa9b5219f8 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -75,6 +75,8 @@ static Property pci_props[] = {
>                      QEMU_PCIE_LNKSTA_DLLLA_BITNR, true),
>      DEFINE_PROP_BIT("x-pcie-extcap-init", PCIDevice, cap_present,
>                      QEMU_PCIE_EXTCAP_INIT_BITNR, true),
> +    DEFINE_PROP_STRING("net_failover_pair_id", PCIDevice,
> +            net_failover_pair_id),

Nit, white space appears broken here.

>      DEFINE_PROP_END_OF_LIST()
>  };
>  
> @@ -2077,6 +2079,7 @@ static void pci_qdev_realize(DeviceState *qdev, Error **errp)
>      ObjectClass *klass = OBJECT_CLASS(pc);
>      Error *local_err = NULL;
>      bool is_default_rom;
> +    uint16_t class_id;
>  
>      /* initialize cap_present for pci_is_express() and pci_config_size(),
>       * Note that hybrid PCIs are not set automatically and need to manage
> @@ -2101,6 +2104,20 @@ static void pci_qdev_realize(DeviceState *qdev, Error **errp)
>          }
>      }
>  
> +    if (pci_dev->net_failover_pair_id) {
> +        if (!pci_is_express(pci_dev)) {
> +            error_setg(errp, "failover device is not a PCIExpress device");
> +            error_propagate(errp, local_err);
> +            return;
> +        }

Did we decide we don't need to test that the device is also in a
hotpluggable slot?  Are there also multi-function considerations that
should be prevented or documented?  For example, if a user tries to
configure both the primary and failover NICs in the same slot, I assume
bad things will happen.

> +        class_id = pci_get_word(pci_dev->config + PCI_CLASS_DEVICE);
> +        if (class_id != PCI_CLASS_NETWORK_ETHERNET) {
> +            error_setg(errp, "failover device is not an Ethernet device");
> +            error_propagate(errp, local_err);
> +            return;
> +        }
> +    }

Looks like cleanup is missing both both error cases, the option rom
error path below this does a pci_qdev_unrealize() before returning so
I'd assume we want the same here.  Thanks,

Alex

> +
>      /* rom loading */
>      is_default_rom = false;
>      if (pci_dev->romfile == NULL && pc->romfile != NULL) {
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index f3f0ffd5fb..def5435685 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -352,6 +352,9 @@ struct PCIDevice {
>      MSIVectorUseNotifier msix_vector_use_notifier;
>      MSIVectorReleaseNotifier msix_vector_release_notifier;
>      MSIVectorPollNotifier msix_vector_poll_notifier;
> +
> +    /* ID of standby device in net_failover pair */
> +    char *net_failover_pair_id;
>  };
>  
>  void pci_register_bar(PCIDevice *pci_dev, int region_num,