[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: RE: [virtio-comment] Re: [PATCH v6 2/5] virtio-net: Add flow filter capabilities read commands
> From: Michael S. Tsirkin <mst@redhat.com> > Sent: Monday, November 27, 2023 4:58 PM > > On Mon, Nov 27, 2023 at 10:19:49AM +0000, Parav Pandit wrote: > > > > > From: Michael S. Tsirkin <mst@redhat.com> > > > Sent: Friday, November 24, 2023 5:04 PM > > > > > > On Fri, Nov 24, 2023 at 06:31:03AM +0000, Parav Pandit wrote: > > > > > > > > > From: Michael S. Tsirkin <mst@redhat.com> > > > > > Sent: Friday, November 24, 2023 11:48 AM > > > > > > > > > > On Fri, Nov 24, 2023 at 05:40:26AM +0000, Parav Pandit wrote: > > > > > > > we > > > > > > > strongly suggest that *drivers* support both old and new > > > > > > > mechanism, and then *devices* will only implement what's > required. > > > > > > There are other examples in the same document that makes > > > > > > things worst > > > > > with old and new. > > > > > > > > > > > > Also there is literally no way to enforce that driver supports > > > > > > both and new. It is just sounds like an excuse to force > > > > > > infinite config space. > > > > > > > > > > There is a very simple method though. We allow devices to > > > > > expose a subset of features when DMA is not used. So drivers > > > > > that want maximum features will always opt for DMA. We can also > > > > > strongly recommend that all drivers support DMA if available. > > > > Yeah, don't see how this is elegant at all with all mixed bits. > > > > > > It's elegant because simple low end devices can cheaply implement > > > MMIO and not worry about DMA. > > > > > It is not of much help in this case because any low end cheap device which > want to support flow filter commands need to have CVQ anyway. > > And hence reusing the same CVQ is more elegant that already does the DMA. > > > > So CVQ is fulfilling all the below needs. > > 1. Single interface for the get/set config flow filters 2. DMA the > > data 3. Not have any partial issues > > I don't know what these are. I mean partial writes for fields. > > > 4. provides consistent structures that provisioning side will be able > > to use > > Problem for provisioning is extra definitions will be needed, in a device specific > way. In vdpa tool and other OS tools of iproute2 developed, setting and getting those device specific values are useful. It is ok. > > > > > Nor do I see any enforcement, single method via cvq still holds strong. > > > > > > You don't need to enforce things, if people want to put a lot of RAM > > > on device and put it in a register let them. > > > > > Not enforced. It uses the CVQ for flow group and flow filter life cycles and for > the sharing this config as well. > > Also aligns with stats that rest also agreed on. > > I am talking about your attempt to generally say "no more config fields > everything must be in CVQ". Config fields for initialization time is fine as the spec allows it today. Things which can differ, it is ok to use cvq interface. > I think it's wrong definitiely for non network > devices must sometimes for network too and generally we need a solution for > config over DMA. This specific thing - whether it fits in CVQ is a separate > discussion. > I explained it before, that 6 out of 19 devices has cvq which are complex enough doing things over cvq. These are non-network devices already. If one of those remaining device becomes complex, it is likely it will need a cvq to suffice for the dma interface and it can just do with depth = 1. > > > > > > > > > > > > > > > > > > > > > > > > > > The method proposed here is elegant and clearly promote one > > > > > > way to do > > > > > things for driver and device with predictability. > > > > > > > > > > > > > > > > I don't see it as elegant at all. What is elegant is *a single > > > > > tag* that describes each property of the device. And this single > > > > > tag should be > > > good for everything: > > > > > driver, provisioning, migration. And config space offset serves as such. > > > > The single tag is the set of structures. > > > > > > I have no idea how this will work. If migration format i started > > > reviewing is anything to go by then there will be a huge elaborate > > > structure nothing single or simple. By comparison there's already a > > > proposal how provisioning can work by supplying config space. > > > it is just a clean model to grasp. > > > > > The provisioning model is simple is to supply all the configuration. > > To draw parallels to some sw side, > > > > There is per functionality socket option to set things, instead of one giant > structure. > > There is per functionality ethtool option/cmd instead of Set ALL/get ALL > enforcement. > > I'm not sure how much of a parallel one can draw. > Do not see a lot of similarity. For lot of configuration they are similar that happens at slow pace. > Devices commonly use register map. Everyone understands this paradigm. > For initialization early device setup time, yes. > > I am not altogether happy with the way you are making migration generate > duplicate definitions for lots of things we already have definitions for. > Having a 3rd one for provisioning? Gimme a break. For migration, we are not duplicating. Some structures are not well defined, it has some duplication. But large part seems be able to utilized pre-defined structs. And here for flow filter also same structs will be used. > > > > > > Provisioning access them via owner device. > > > > Member driver access them via CVQ or 1.2 legacy config space. > > >
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]