On Fri, 2012-01-13 at 22:00 +0100, Jan Kiszka wrote: > On 2012-01-04 04:21, Alex Williamson wrote: > > On Mon, 2011-12-19 at 19:49 +0530, Shashidhar Patil wrote: > >> Hi, > >> I am running Ubuntu 10.10 (amd64) on a 2 socket nehalem based > >> server with IOH 5520. 5520 supports VTD. > >> I enabled DMAR with intel_iommu=on. The box has intel 82599 adapter > >> which I assigned through VT-D to FreeBSD 8.2 running > >> as guest os. The ixgbe driver detects the device and the driver > >> successfully configures the device. But the link > >> never comes up. It looks like link up/down interrupts are not > >> delivered. Then I checked kvm interrupt assignment and as expected > >> kvm could not make MSI-X entries for the VT-d guest. So no output from > >> "grep kvm /proc/interrupt". By enabling some debugs in the > >> qemu-kvm I figured out that the MSI-x updates are not received > >> properly. It does look like Linux updates MSI-X table in a batch > >> fashion > >> which qemu-kvm gets in one shot and every thing works fine in case of > >> linux. In case of FreeBSD PCIE updates come /MSI-X entry > >> which qemu-kvm can't make use. > > > > That's right, Linux and Windows both seem to setup the MSI-X table then > > enable it in one shot, so we only trigger the interrupt programming when > > the enable bit is set. We don't trigger changes on writes to the MSI-X > > table... not very accurate emulation of mask bits. > > According to the PCI spec, updates that happen while a vector is > unmasked, need not be considered by the hardware (thus the hypervisor > here). Is that the scenario here? I'm assuming the vector is masked in the MSI-X table. So Linux/Windows do: a) program MSI-X table b) enable MSI-X in capability register Whereas FreeBSD does: a) enable MSI-X in capability register (vectors masked in table) b) program and unmask individual vectors Thanks, Alex -- 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
