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Subject: Re: [virtio-dev] [PATCH v4] content: Introduce VIRTIO_NET_F_STANDBY feature
On Tue, Sep 18, 2018 at 6:25 AM, Michael S. Tsirkin <mst@redhat.com> wrote: > On Tue, Sep 18, 2018 at 01:37:35PM +0300, Sameeh Jubran wrote: >> On Tue, Sep 18, 2018 at 1:21 PM Cornelia Huck <cohuck@redhat.com> wrote: >> > >> > On Wed, 12 Sep 2018 11:22:12 -0400 >> > "Michael S. Tsirkin" <mst@redhat.com> wrote: >> > >> > > On Wed, Sep 12, 2018 at 08:17:45AM -0700, Samudrala, Sridhar wrote: >> > > > >> > > > >> > > > On 9/7/2018 2:34 PM, Michael S. Tsirkin wrote: >> > > > > On Wed, Aug 15, 2018 at 11:49:15AM -0700, Sridhar Samudrala wrote: >> > > > > > VIRTIO_NET_F_STANDBY feature enables hypervisor to indicate virtio_net >> > > > > > device to act as a standby for another device with the same MAC address. >> > > > > > >> > > > > > Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com> >> > > > > > Acked-by: Cornelia Huck <cohuck@redhat.com> >> > > > > > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/18 >> > > > > Applied but when do you plan to add documentation as pointed >> > > > > out by Jan and Halil? >> > > > >> > > > I thought additional documentation will be done as part of the Qemu enablement >> > > > patches and i hope someone in RH is looking into it. >> > > > >> > > > Does it make sense to add a link to to the kernel documentation of this feature in >> > > > the spec >> > > > https://www.kernel.org/doc/html/latest/networking/net_failover.html >> > > >> > > >> > > I do not think this will address the comments posted. Specifically we >> > > should probably include documentation for what is a standby and primary: >> > > what is expected of driver (maintain configuration on standby, support >> > > primary coming and going, transmit on standby only if there is no >> > > primary) and of device (have same mac for standby as for standby). >> > >> > Yes, we need some definitive statements of what a driver and a device >> > is supposed to do in order to conform; it might make sense to discuss >> > this in conjunction with discussion on any QEMU patches (have not >> > checked whether anything has been posted, just returned from vacation). >> > >> > I assume that we still stick with the plan to implement/document >> > MAC-based handling first and then enhance with other methods later? >> >> I am currently in the process of writing the patches for this feature, >> I have thought about how the feature should be implemented >> and decided to go with a different approach. I've decided that the id >> of the vfio attached device will be specified in the virtio-net >> arguments as follows: >> >> -device virtio-net,standby=<device_id_of_vfio_device> >> -vfio #address,id=<device_id_of_vfio_device> >> >> This approach makes minimal changes to the current infrastructure and >> does so elegantly without adding unnecessary ids to the bridges. >> >> The mac address approach seems to be very complicated as there is no >> standard way to find the mac address of a given device and it is >> vendor dependent, >> which makes the task of identifying the target standby device by it's >> mac address a very tough one. > > Oh mac address is used by guest. I agree it's not a great qemu > interface. > The idea was basically to have -vfio #address,primary=<id> Interesting... How do you make sure the MAC address are same (grouped) between vfio and virtio-net-pci (from QEMU side)? I thought the spec meant to make this a guest-host interface, right? -Siwei > > >> Please share your thoughts so I'll move forward with the patches. > > Can this actually support hotplug add and remove of the vfio device though? > E.g. hotplug add vfio device while VM is already running? > With the primary=<> it works because standby must always exist > even when primary isn't there. > > >> An initial patch which implements hiding the device from pci bus >> before the feature is acked is provided below: >> >> commit b716371bf4807fe16ffb4ffd901b69a110902a3c (HEAD -> failover) >> Author: Sameeh Jubran <sjubran@redhat.com> >> Date: Sun Sep 16 13:21:41 2018 +0300 >> >> virtio-net: Implement standby feature >> >> Signed-off-by: Sameeh Jubran <sjubran@redhat.com> >> >> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c >> index f154756e85..46386c0e1b 100644 >> --- a/hw/net/virtio-net.c >> +++ b/hw/net/virtio-net.c >> @@ -26,7 +26,9 @@ >> #include "qapi/qapi-events-net.h" >> #include "hw/virtio/virtio-access.h" >> #include "migration/misc.h" >> +#include "hw/pci/pci.h" >> #include "standard-headers/linux/ethtool.h" >> +#include "hw/vfio/vfio-common.h" >> >> #define VIRTIO_NET_VM_VERSION 11 >> >> @@ -1946,6 +1948,13 @@ void virtio_net_set_netclient_name(VirtIONet >> *n, const char *name, >> n->netclient_type = g_strdup(type); >> } >> >> +static bool standby_device_present(VirtIONet *n, const char *id, >> + struct PCIDevice **pdev) >> +{ >> + return pci_qdev_find_device(id, pdev) >= 0 && pdev && >> + vfio_is_vfio_pci(*pdev); >> +} >> + >> static void virtio_net_device_realize(DeviceState *dev, Error **errp) >> { >> VirtIODevice *vdev = VIRTIO_DEVICE(dev); >> @@ -1976,6 +1985,21 @@ static void >> virtio_net_device_realize(DeviceState *dev, Error **errp) >> n->host_features |= (1ULL << VIRTIO_NET_F_SPEED_DUPLEX); >> } >> >> + if (n->net_conf.standby_id_str && standby_device_present(n, >> + n->net_conf.standby_id_str, &n->standby_pdev)) { >> + DeviceState *dev = DEVICE(n->standby_pdev); >> + DeviceClass *klass = DEVICE_GET_CLASS(dev); >> + /* Hide standby from pci till the feature is acked */ >> + if (klass->hotpluggable) >> + { >> + qdev_unplug(dev, errp); > > > Does this really hide the device? > I see: > hdc = HOTPLUG_HANDLER_GET_CLASS(hotplug_ctrl); > if (hdc->unplug_request) { > hotplug_handler_unplug_request(hotplug_ctrl, dev, errp); > } else { > hotplug_handler_unplug(hotplug_ctrl, dev, errp); > } > > which seems to just send an eject request to guest - the reverse of > what we want to do. > >> + if (errp == NULL) >> + { >> + n->host_features |= (1ULL << VIRTIO_NET_F_STANDBY); >> + } > > I'm not sure how is this error handling supposed to work. > >> + } >> + } >> + >> virtio_net_set_config_size(n, n->host_features); >> virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size); >> >> @@ -2198,6 +2222,7 @@ static Property virtio_net_properties[] = { >> true), >> DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed, SPEED_UNKNOWN), >> DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str), >> + DEFINE_PROP_STRING("standby", VirtIONet, net_conf.standby_id_str), >> DEFINE_PROP_END_OF_LIST(), >> }; >> >> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c >> index 866f0deeb7..593debe56e 100644 >> --- a/hw/vfio/pci.c >> +++ b/hw/vfio/pci.c >> @@ -220,6 +220,12 @@ static void vfio_intx_disable_kvm(VFIOPCIDevice *vdev) >> #endif >> } >> >> +bool vfio_is_vfio_pci(PCIDevice* pdev) >> +{ >> + VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev); >> + return vdev->vbasedev.type == VFIO_DEVICE_TYPE_PCI; >> +} >> + >> static void vfio_intx_update(PCIDevice *pdev) >> { >> VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev); >> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h >> index 821def0565..26dfde805f 100644 >> --- a/include/hw/vfio/vfio-common.h >> +++ b/include/hw/vfio/vfio-common.h >> @@ -195,5 +195,6 @@ int vfio_spapr_create_window(VFIOContainer *container, >> hwaddr *pgsize); >> int vfio_spapr_remove_window(VFIOContainer *container, >> hwaddr offset_within_address_space); >> +bool vfio_is_vfio_pci(PCIDevice* pdev); >> >> #endif /* HW_VFIO_VFIO_COMMON_H */ >> diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h >> index 4d7f3c82ca..94388b40cb 100644 >> --- a/include/hw/virtio/virtio-net.h >> +++ b/include/hw/virtio/virtio-net.h >> @@ -42,6 +42,7 @@ typedef struct virtio_net_conf >> int32_t speed; >> char *duplex_str; >> uint8_t duplex; >> + char *standby_id_str; >> } virtio_net_conf; >> >> /* Maximum packet size we can receive from tap device: header + 64k */ >> @@ -103,6 +104,7 @@ typedef struct VirtIONet { >> int announce_counter; >> bool needs_vnet_hdr_swap; >> bool mtu_bypass_backend; >> + PCIDevice *standby_pdev; >> } VirtIONet; >> >> void virtio_net_set_netclient_name(VirtIONet *n, const char *name, >> (END) >> >> > >> > --------------------------------------------------------------------- >> > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org >> > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org >> > >> >> >> -- >> Respectfully, >> Sameeh Jubran >> Linkedin >> Software Engineer @ Daynix. > > --------------------------------------------------------------------- > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org >
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