On Fri, 25 May 2012, Thomas Gleixner wrote: > On Fri, 25 May 2012, Michael S. Tsirkin wrote: > > On Thu, May 24, 2012 at 06:53:15PM -0300, Jan Kiszka wrote: > > > On 2012-05-24 18:39, Thomas Gleixner wrote: > > > > On Thu, 24 May 2012, Alex Williamson wrote: > > > >> On Thu, 2012-05-24 at 18:02 +0100, Richard Weinberger wrote: > > > >>> + if (address == msi_start + PCI_MSI_DATA_32) > > > >>> + handle_cfg_write_msi(pci_dev, assigned_dev); > > > >> > > > >> Why didn't we just use range_covers_byte(address, len, pci_dev->msi_cap > > > >> + PCI_MSI_DATA_32) to start with? But how does this handle the enable > > > >> bit? > > > > > > > > The problem with the current implementation is that it only changes > > > > the routing if the msi entry goes from masked to unmasked state. > > > > > > > > Linux does not mask the entries on affinity changes and never did, > > > > neither for MSI nor for MSI-X. > > > > > > > > I know it's probably not according to the spec, but we can't fix that > > > > retroactively. > > > > > > For MSI, this is allowed. For MSI-X, this would clearly be a Linux bug, > > > waiting for hardware to dislike this spec violation. > > > > > > However, if this is the current behavior of such a prominent guest, I > > > guess we have to stop optimizing the QEMU MSI-X code that it only > > > updates routings on mask changes. Possibly other OSes get this wrong too... > > > > Very strange, a clear spec violation. I'll have to dig in the source to > > verify this. > > Stop digging. MSI-X is correct. This was based off an older version of qemu-kvm, where the routing for MSI-X was broken for other reasons. But that seems to be fixed now. I use the age excuse :) Thanks, tglx -- 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
