On Thu, Dec 03, 2020 at 08:49:28AM +0200, Eli Cohen wrote:
> On Wed, Dec 02, 2020 at 05:00:22PM -0500, Michael S. Tsirkin wrote:
> > On Wed, Dec 02, 2020 at 09:48:25PM +0800, Jason Wang wrote:
> > >
> > > On 2020/12/2 下午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 下午5:23, Cindy Lu wrote:
> > > > > > > On Mon, Nov 30, 2020 at 11:33 PM Michael S.
> > > > > > > Tsirkin<m...@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<m...@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<l...@redhat.com>
> > > > > > > > > > > > > > > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver
> > > > > > > > > > > > > > > for supported mlx5 devices")
> > > > > > > > > > > > > > > Signed-off-by: Eli Cohen<e...@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-sae...@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
> > >
> >
> > We can have management set a MAC address. Randomizing it in kernel
> > does not seem like a reasonable policy to me ...
> >
>
> This manangement should be the VDPA tool that Parav is pushing. We can
> use it to set a MAC chosen by the user. The mlx5 vdpa driver can then
> use that MAC instead of randomizing a value. If no admin value is given
> we can use a random MAC.
IIUC in this model devices are created by this tool, right?
Why not require the MAC when device is created?
> >
> > > >
> > > >
> > > >
> > > >
> >
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