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Re: [Xen-devel] Bug when disabling/enabling a PT device with MSI enabled

To: Tom Rotenberg <tom.rotenberg@xxxxxxxxx>
Subject: Re: [Xen-devel] Bug when disabling/enabling a PT device with MSI enabled
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Tue, 24 Nov 2009 14:48:15 -0500
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On Tue, Nov 24, 2009 at 08:42:49PM +0200, Tom Rotenberg wrote:
> Hi,
> I am using the xen-3,4, and i am doing pass-through for a device with
> MSI enabled (the device of-course supports MSI) to a domU with Windows
> XP. When i disable and then re-enable the device using Windows device
> manager, everything looks like it's working fine, but the device seems
> to malfunction.
> After digging a little bit, i saw that the problem is, because the bit
> of the interrupt-status (bit 3) in the status register (offset 0x6 in
> the PCI config space) was turned on somehow -  this proibably caused
> the MSI to malfunction (because the IntX assertion was enabled - thus
> disabling the MSI) - and this lead to the problem i experienced.
> Any ideas on how to solve this issue?

Looks like QEMU is not doing its job. It ought to be tracking
when an MSI devices transforms to a INTx PCI device (and vice-versa) and
make the appropiate Xen calls. Look in ioemu-dir/hw/pass-through.c

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