Michael S. Tsirkin
2020-Dec-02 09:23 UTC
[PATCH] vdpa/mlx5: Use random MAC for the vdpa net instance
On Wed, Dec 02, 2020 at 07:57:14AM +0200, Eli Cohen wrote:> On Wed, Dec 02, 2020 at 12:18:36PM +0800, Jason Wang wrote: > > > > On 2020/12/1 ??5:23, Cindy Lu wrote: > > > On Mon, Nov 30, 2020 at 11:33 PM Michael S. Tsirkin <mst at redhat.com> wrote: > > > > On Mon, Nov 30, 2020 at 06:41:45PM +0800, Cindy Lu wrote: > > > > > On Mon, Nov 30, 2020 at 5:33 PM Michael S. Tsirkin <mst at redhat.com> wrote: > > > > > > On Mon, Nov 30, 2020 at 11:27:59AM +0200, Eli Cohen wrote: > > > > > > > On Mon, Nov 30, 2020 at 04:00:51AM -0500, Michael S. Tsirkin wrote: > > > > > > > > On Mon, Nov 30, 2020 at 08:27:46AM +0200, Eli Cohen wrote: > > > > > > > > > On Sun, Nov 29, 2020 at 03:08:22PM -0500, Michael S. Tsirkin wrote: > > > > > > > > > > On Sun, Nov 29, 2020 at 08:43:51AM +0200, Eli Cohen wrote: > > > > > > > > > > > We should not try to use the VF MAC address as that is used by the > > > > > > > > > > > regular (e.g. mlx5_core) NIC implementation. Instead, use a random > > > > > > > > > > > generated MAC address. > > > > > > > > > > > > > > > > > > > > > > Suggested by: Cindy Lu <lulu at redhat.com> > > > > > > > > > > > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices") > > > > > > > > > > > Signed-off-by: Eli Cohen <elic at nvidia.com> > > > > > > > > > > I didn't realise it's possible to use VF in two ways > > > > > > > > > > with and without vdpa. > > > > > > > > > Using a VF you can create quite a few resources, e.g. send queues > > > > > > > > > recieve queues, virtio_net queues etc. So you can possibly create > > > > > > > > > several instances of vdpa net devices and nic net devices. > > > > > > > > > > > > > > > > > > > Could you include a bit more description on the failure > > > > > > > > > > mode? > > > > > > > > > Well, using the MAC address of the nic vport is wrong since that is the > > > > > > > > > MAC of the regular NIC implementation of mlx5_core. > > > > > > > > Right but ATM it doesn't coexist with vdpa so what's the problem? > > > > > > > > > > > > > > > This call is wrong: mlx5_query_nic_vport_mac_address() > > > > > > > > > > > > > > > > > Is switching to a random mac for such an unusual > > > > > > > > > > configuration really justified? > > > > > > > > > Since I can't use the NIC's MAC address, I have two options: > > > > > > > > > 1. To get the MAC address as was chosen by the user administering the > > > > > > > > > NIC. This should invoke the set_config callback. Unfortunately this > > > > > > > > > is not implemented yet. > > > > > > > > > > > > > > > > > > 2. Use a random MAC address. This is OK since if (1) is implemented it > > > > > > > > > can always override this random configuration. > > > > > > > > > > > > > > > > > > > It looks like changing a MAC could break some guests, > > > > > > > > > > can it not? > > > > > > > > > > > > > > > > > > > No, it will not. The current version of mlx5 VDPA does not allow regular > > > > > > > > > NIC driver and VDPA to co-exist. I have patches ready that enable that > > > > > > > > > from steering point of view. I will post them here once other patches on > > > > > > > > > which they depend will be merged. > > > > > > > > > > > > > > > > > > https://patchwork.ozlabs.org/project/netdev/patch/20201120230339.651609-12-saeedm at nvidia.com/ > > > > > > > > Could you be more explicit on the following points: > > > > > > > > - which configuration is broken ATM (as in, two device have identical > > > > > > > > macs? any other issues)? > > > > > > > The only wrong thing is the call to mlx5_query_nic_vport_mac_address(). > > > > > > > It's not breaking anything yet is wrong. The random MAC address setting > > > > > > > is required for the steering patches. > > > > > > Okay so I'm not sure the Fixes tag at least is appropriate if it's a > > > > > > dependency of a new feature. > > > > > > > > > > > > > > - why won't device MAC change from guest point of view? > > > > > > > > > > > > > > > It's lack of implementation in qemu as far as I know. > > > > > > Sorry not sure I understand. What's not implemented in QEMU? > > > > > > > > > > > HI Michael, there are some bug in qemu to set_config, this will fix in future, > > > > > But this patch is still needed, because without this patch the mlx > > > > > driver will give an 0 mac address to qemu > > > > > and qemu will overwrite the default mac address. This will cause traffic down. > > > > Hmm the patch description says VF mac address, not 0 address. Confused. > > > > If there's no mac we can clear VIRTIO_NET_F_MAC and have guest > > > > use a random value ... > > > > > > I'm not sure this can work for all types of vDPA (e.g it could not be a > > learning bridge in the swtich). > > > > > > > > > > > hi Michael? > > > I have tried as your suggestion, seems even remove the > > > VIRTIO_NET_F_MAC the qemu will still call get_cinfig and overwrite the > > > default address in VM, > > > > > > This looks a bug in qemu, in guest driver we had: > > > > ??? /* Configuration may specify what MAC to use.? Otherwise random. */ > > ??? if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) > > ??? ??? virtio_cread_bytes(vdev, > > ??? ??? ??? ??? ?? offsetof(struct virtio_net_config, mac), > > ??? ??? ??? ??? ?? dev->dev_addr, dev->addr_len); > > ??? else > > ??? ??? eth_hw_addr_random(dev); > > > > > > > this process is like > > > vdpa _init -->qemu call get_config ->mlx driver will give an mac > > > address with all 0--> > > > qemu will not check this mac address and use it --> overwrite the mac > > > address in qemu > > > > > > So for my understanding there are several method to fix this problem > > > > > > 1, qemu check the mac address, if the mac address is all 0, qemu will > > > ignore it and set the random mac address to mlx driver. > > > > > > So my understanding is that, if mac address is all 0, vDPA parent should not > > advertise VIRTIO_NET_F_MAC. And qemu should emulate this feature as you did: > > Thinking it over, at least in mlx5, I should always advertise > VIRTIO_NET_F_MAC and set a non zero MAC value. The source of the MAC can > be either randomly generated value by mlx5_vdpa or by a management tool. > This is important becauase we should not let the VM modify the MAC. If > we do it can set a MAC value identical to the mlx5 NIC driver and can > kidnap traffic that was not destined to it. > > In addition, when VIRTIO_NET_F_MAC is published, attempts to change the > MAC address from the VM should result in error.That is not what the spec says though. VIRTIO_NET_F_MAC only says whether mac is valid in the config space. Whether guest can control that depends on VIRTIO_NET_F_CTRL_MAC_ADDR: The VIRTIO_NET_CTRL_MAC_ADDR_SET command is used to set the default MAC address which rx filtering accepts (and if VIRTIO_NET_F_MAC_ADDR has been negotiated, this will be reflected in mac in config space). The command-specific-data for VIRTIO_NET_CTRL_MAC_ADDR_SET is the 6-byte MAC address.> > > > > 1) get a random mac > > 2) advertise VIRTIO_NET_F_MAC > > 3) set the random mac to vDPA through set_config > > 4) advertise the random mac to emulated config to guest > > > > > > > 2. mlx driver checks the mac address and if this mac is 0, return fail > > > to qemu, but this need to change the UAPI. > > > > > > uAPI is probably fine since ioctl can fail.? We can change the to allow the > > set_config to fail but virito spec doesn't have a way to advertise the error > > in this case. Anyway, the driver only risk itself for setting a wrong value, > > so we're probably fine. > > > > Thanks > > > > > > > 3. mlx driver it shelf should get an correct mac address while it init. > > > 4. add check in qemu get_config function , if there is not F_MAC Then > > > ignore the mac address from mlx driver > > > > > > not sure which method is more suitable ? > > > > > > Thanks > > > Cindy > > > > > > > > > > > > > > > > > > > > --- > > > > > > > > > > > drivers/vdpa/mlx5/net/mlx5_vnet.c | 5 +---- > > > > > > > > > > > 1 file changed, 1 insertion(+), 4 deletions(-) > > > > > > > > > > > > > > > > > > > > > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > > > > > > > > > > index 1fa6fcac8299..80d06d958b8b 100644 > > > > > > > > > > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c > > > > > > > > > > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c > > > > > > > > > > > @@ -1955,10 +1955,7 @@ void *mlx5_vdpa_add_dev(struct mlx5_core_dev *mdev) > > > > > > > > > > > if (err) > > > > > > > > > > > goto err_mtu; > > > > > > > > > > > > > > > > > > > > > > - err = mlx5_query_nic_vport_mac_address(mdev, 0, 0, config->mac); > > > > > > > > > > > - if (err) > > > > > > > > > > > - goto err_mtu; > > > > > > > > > > > - > > > > > > > > > > > + eth_random_addr(config->mac); > > > > > > > > > > > mvdev->vdev.dma_dev = mdev->device; > > > > > > > > > > > err = mlx5_vdpa_alloc_resources(&ndev->mvdev); > > > > > > > > > > > if (err) > > > > > > > > > > > -- > > > > > > > > > > > 2.26.2 > >
Jason Wang
2020-Dec-02 13:48 UTC
[PATCH] vdpa/mlx5: Use random MAC for the vdpa net instance
On 2020/12/2 ??5:23, Michael S. Tsirkin wrote:> On Wed, Dec 02, 2020 at 07:57:14AM +0200, Eli Cohen wrote: >> On Wed, Dec 02, 2020 at 12:18:36PM +0800, Jason Wang wrote: >>> On 2020/12/1 ??5:23, Cindy Lu wrote: >>>> On Mon, Nov 30, 2020 at 11:33 PM Michael S. Tsirkin<mst at redhat.com> wrote: >>>>> On Mon, Nov 30, 2020 at 06:41:45PM +0800, Cindy Lu wrote: >>>>>> On Mon, Nov 30, 2020 at 5:33 PM Michael S. Tsirkin<mst at redhat.com> wrote: >>>>>>> On Mon, Nov 30, 2020 at 11:27:59AM +0200, Eli Cohen wrote: >>>>>>>> On Mon, Nov 30, 2020 at 04:00:51AM -0500, Michael S. Tsirkin wrote: >>>>>>>>> On Mon, Nov 30, 2020 at 08:27:46AM +0200, Eli Cohen wrote: >>>>>>>>>> On Sun, Nov 29, 2020 at 03:08:22PM -0500, Michael S. Tsirkin wrote: >>>>>>>>>>> On Sun, Nov 29, 2020 at 08:43:51AM +0200, Eli Cohen wrote: >>>>>>>>>>>> We should not try to use the VF MAC address as that is used by the >>>>>>>>>>>> regular (e.g. mlx5_core) NIC implementation. Instead, use a random >>>>>>>>>>>> generated MAC address. >>>>>>>>>>>> >>>>>>>>>>>> Suggested by: Cindy Lu<lulu at redhat.com> >>>>>>>>>>>> Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices") >>>>>>>>>>>> Signed-off-by: Eli Cohen<elic at nvidia.com> >>>>>>>>>>> I didn't realise it's possible to use VF in two ways >>>>>>>>>>> with and without vdpa. >>>>>>>>>> Using a VF you can create quite a few resources, e.g. send queues >>>>>>>>>> recieve queues, virtio_net queues etc. So you can possibly create >>>>>>>>>> several instances of vdpa net devices and nic net devices. >>>>>>>>>> >>>>>>>>>>> Could you include a bit more description on the failure >>>>>>>>>>> mode? >>>>>>>>>> Well, using the MAC address of the nic vport is wrong since that is the >>>>>>>>>> MAC of the regular NIC implementation of mlx5_core. >>>>>>>>> Right but ATM it doesn't coexist with vdpa so what's the problem? >>>>>>>>> >>>>>>>> This call is wrong: mlx5_query_nic_vport_mac_address() >>>>>>>> >>>>>>>>>>> Is switching to a random mac for such an unusual >>>>>>>>>>> configuration really justified? >>>>>>>>>> Since I can't use the NIC's MAC address, I have two options: >>>>>>>>>> 1. To get the MAC address as was chosen by the user administering the >>>>>>>>>> NIC. This should invoke the set_config callback. Unfortunately this >>>>>>>>>> is not implemented yet. >>>>>>>>>> >>>>>>>>>> 2. Use a random MAC address. This is OK since if (1) is implemented it >>>>>>>>>> can always override this random configuration. >>>>>>>>>> >>>>>>>>>>> It looks like changing a MAC could break some guests, >>>>>>>>>>> can it not? >>>>>>>>>>> >>>>>>>>>> No, it will not. The current version of mlx5 VDPA does not allow regular >>>>>>>>>> NIC driver and VDPA to co-exist. I have patches ready that enable that >>>>>>>>>> from steering point of view. I will post them here once other patches on >>>>>>>>>> which they depend will be merged. >>>>>>>>>> >>>>>>>>>> https://patchwork.ozlabs.org/project/netdev/patch/20201120230339.651609-12-saeedm at nvidia.com/ >>>>>>>>> Could you be more explicit on the following points: >>>>>>>>> - which configuration is broken ATM (as in, two device have identical >>>>>>>>> macs? any other issues)? >>>>>>>> The only wrong thing is the call to mlx5_query_nic_vport_mac_address(). >>>>>>>> It's not breaking anything yet is wrong. The random MAC address setting >>>>>>>> is required for the steering patches. >>>>>>> Okay so I'm not sure the Fixes tag at least is appropriate if it's a >>>>>>> dependency of a new feature. >>>>>>> >>>>>>>>> - why won't device MAC change from guest point of view? >>>>>>>>> >>>>>>>> It's lack of implementation in qemu as far as I know. >>>>>>> Sorry not sure I understand. What's not implemented in QEMU? >>>>>>> >>>>>> HI Michael, there are some bug in qemu to set_config, this will fix in future, >>>>>> But this patch is still needed, because without this patch the mlx >>>>>> driver will give an 0 mac address to qemu >>>>>> and qemu will overwrite the default mac address. This will cause traffic down. >>>>> Hmm the patch description says VF mac address, not 0 address. Confused. >>>>> If there's no mac we can clear VIRTIO_NET_F_MAC and have guest >>>>> use a random value ... >>> I'm not sure this can work for all types of vDPA (e.g it could not be a >>> learning bridge in the swtich). >>> >>> >>>> hi Michael? >>>> I have tried as your suggestion, seems even remove the >>>> VIRTIO_NET_F_MAC the qemu will still call get_cinfig and overwrite the >>>> default address in VM, >>> This looks a bug in qemu, in guest driver we had: >>> >>> ??? /* Configuration may specify what MAC to use.? Otherwise random. */ >>> ??? if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) >>> ??? ??? virtio_cread_bytes(vdev, >>> ??? ??? ??? ??? ?? offsetof(struct virtio_net_config, mac), >>> ??? ??? ??? ??? ?? dev->dev_addr, dev->addr_len); >>> ??? else >>> ??? ??? eth_hw_addr_random(dev); >>> >>> >>>> this process is like >>>> vdpa _init -->qemu call get_config ->mlx driver will give an mac >>>> address with all 0--> >>>> qemu will not check this mac address and use it --> overwrite the mac >>>> address in qemu >>>> >>>> So for my understanding there are several method to fix this problem >>>> >>>> 1, qemu check the mac address, if the mac address is all 0, qemu will >>>> ignore it and set the random mac address to mlx driver. >>> So my understanding is that, if mac address is all 0, vDPA parent should not >>> advertise VIRTIO_NET_F_MAC. And qemu should emulate this feature as you did: >> Thinking it over, at least in mlx5, I should always advertise >> VIRTIO_NET_F_MAC and set a non zero MAC value. The source of the MAC can >> be either randomly generated value by mlx5_vdpa or by a management tool. >> This is important becauase we should not let the VM modify the MAC. If >> we do it can set a MAC value identical to the mlx5 NIC driver and can >> kidnap traffic that was not destined to it. >> >> In addition, when VIRTIO_NET_F_MAC is published, attempts to change the >> MAC address from the VM should result in error. > That is not what the spec says though. > VIRTIO_NET_F_MAC only says whether mac is valid in the config space. > Whether guest can control that depends on VIRTIO_NET_F_CTRL_MAC_ADDR: > > The VIRTIO_NET_CTRL_MAC_ADDR_SET command is used to set the default MAC address which rx > filtering accepts (and if VIRTIO_NET_F_MAC_ADDR has been negotiated, this will be reflected in mac in > config space). > The command-specific-data for VIRTIO_NET_CTRL_MAC_ADDR_SET is the 6-byte MAC address.Consider VIRTIO_NET_CTRL_MAC_ADDR_SET is not supported now. What Eli proposed here should work? Thanks> > > >