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Subject: Re: [virtio-comment] Re: [PATCH] virtio-net: introduce admin control virtqueue
On 2021/1/22 äå8:14, Michael S. Tsirkin wrote:
On Fri, Jan 22, 2021 at 04:14:19AM -0500, Jason Wang wrote:----- Original Message -----On Fri, Jan 22, 2021 at 03:41:23AM -0500, Jason Wang wrote:----- Original Message -----On Fri, Jan 22, 2021 at 04:23:25PM +0800, Jason Wang wrote:When implementing multiple (sub)functions virtio device like SRIOV or sub-function. We're suffering from several issues: - There's no management interface for management function (PF) to configure features, attributes for a (sub)function - Per (sub)function control virtqueue could be too expensive as the number of (sub)functions could be very large - Virtualize per (sub)function control virtqueue could be very challenge as we need the support of DMA isolation at queue level So this patch introduces the feature of VIRTIO_NET_CTRL_ADMIN_VQ. This allows the device to implement a single admin control virtqueue to manage per (sub)function features and attributes. The idea is simple, a new function id is introduced on top of the exist virtio_net_ctrl structure. This id is transport or device specific to uniquely identify a (sub)function. With this, we get a way of using management function (PF) to configure per (sub)function features and attributes. And since the admin control virtqueue belongs to management function (PF), the DMA is naturally isolated at (sub)function level instead of the queue level for per (sub)function control vq. Signed-off-by: Jason Wang<jasowang@redhat.com>Let's specify how this works at least for PCI? What about sub-functions under VF level? How are these specified?Ok, will do.--- content.tex | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/content.tex b/content.tex index 620c0e2..98592a4 100644 --- a/content.tex +++ b/content.tex @@ -2940,6 +2940,9 @@ \subsection{Feature bits}\label{sec:Device Types / Network Device / Feature bits \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control channel.+\item[VIRTIO_NET_F_ADMIN_CTRL_VQ(56)] Admin control channel is+ available. + \item[VIRTIO_NET_F_HASH_REPORT(57)] Device can report per-packet hash value and a type of calculated hash.@@ -3864,6 +3867,26 @@ \subsubsection{ControlVirtqueue}\label{sec:Device Types / Network Device / Devi do except issue a diagnostic if \field{ack} is not VIRTIO_NET_OK.+\subsubsection{Admin Control Virtqueue}\label{sec:Device Types /Network Device / Device Operation / Control Virtqueue} + +When VIRTIO_NET_F_ADMIN_CTRL_VQ is negotiated, the driver can use the +control virtqueue to manipulate features of individual function wheremanipulate features? You don't mean feature bits, do you?I copy from the control virtqueue paragraph above: """ The driver uses the control virtqueue (if VIRTIO_NET_F_CTRL_VQ is negotiated) to send commands to manipulate various features of the device which would not easily map into the configuration space. """ Do we need to tweak that part as well? ThanksMaybe, but let's be a bit more specific. For example, is it legal to manipulate the MAC of a VF?Right, so we can clarify that the admin control virtqueue should be only used/advertised for the management function like PF. When neogiated, it's always legal to manipulte the MAC of VF through it.When is it legal?Or do you mean some like "trust" command for iproute2 that allows VF to change its own mac? When PF has admin cvq and VF has normal cvq, management software needs to synrhonize the setting of mac address. E.g management won't set mac address after VM is launched. ThanksConsider. VF has VIRTIO_NET_F_CTRL_MAC_ADDR. This means guest can set mac address. This is something PF needs ability to control. How is this done?
This requires a new command to allow/deny the mac address setting from the VF.
Also, does PF allow setting guest MAC?
I think the answer is yes.
when?
It will work as how ip set vf mac work. Usually, it should be done before launching the guest. Management should make sure there's no conflict in mac address updating.
when PF has VIRTIO_NET_F_CTRL_MAC_ADDR?
Yes, without this feature. We can't set mac address through admin control virtqueue.
Do we differentiate between that and ability to set MAC for pf?
I think not. E.g PF should have a dedicated function_id (or virtual device id) like 0. Then we can set mac address of PF through admin cvq.
Thanks
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