On Tue, 2011-09-06 at 10:49 +0200, Jan Kiszka wrote: > On 2011-09-06 10:46, Sasha Levin wrote: > > On Tue, 2011-09-06 at 10:36 +0200, Jan Kiszka wrote: > >> On 2011-09-06 10:12, Michael S. Tsirkin wrote: > >>> On Tue, Sep 06, 2011 at 10:52:41AM +0300, Avi Kivity wrote: > >>>>> > >>>>> BTW, the same is also true for that optional per-vector masking of > >>>>> legacy MSI. Are there devices in the field that actually support this? I > >>>>> haven't found one so far and tend to consider this feature not worth > >>>>> implementing. > >>>> > >>>> Don't know. I don't like implementing features on the basis of bug > >>>> reports, though. On the other hand we can't really test it without > >>>> a real device. > >>> > >>> Linux will use this capability if present. So > >>> we could add support for an emulated device (e.g. e1000), > >>> then test with nested virt once iommu emulation lands :) > >> > >> Yeah, would be kind of cool. Still, I would feel better having it tested > >> against a real silicon as well. Also to prove that there is a real need. > >> > >> So, in case someone stumbles for such a device (bit 8 set in MSI control > >> word), please let us know! > > > > Doesn't any device that supports MSI-X supports per-vector masking? > > > >>From the spec: > > > > "MSI and MSI-X each support per-vector masking. Per-vector masking is an > > optional extension to MSI, and a standard feature with MSI-X" > > Right, but the cap flag still has to be set. > Are you sure? Take a look at the table in section 6.8.2.3 in the spec (pci v3). Unlike the message control for MSI, this table doesn't mention anything about bit 8 or the per-vector masking capability for MSI-X, it just assumes it's there. > Do you have any MSI-X device in reach? Don't think so, but I think it would be much easier to find a MSI-X device rather than a MSI with per-vector capability. -- Sasha. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
