Re: [Qemu-devel] [V9 2/4] hw/i386: ACPI table for AMD IOMMU

[Valentine Sinitsyn <valentine.sinitsyn@gmail.com>]

On 29.04.2016 13:28, David Kiarie wrote:
> On Fri, Apr 29, 2016 at 9:09 AM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> On 2016-04-25 00:12, David Kiarie wrote:
>>> Add IVRS table for AMD IOMMU. Generate IVRS or DMAR
>>> depending on emulated IOMMU
>>
>> It seems you lack scope descriptions for the PCI devices in the system.
>> At least, this is what our jailhouse config generator complains about
>> right now (didn't look into details yet). If so, the guest OS will
>> likely not configure the IOMMU appropriately as it thinks that the
>> devices are passed through anyway.
>>
>> On Intel, there is an easy way to state "catch them all" in the ACPI
>> table. Maybe AMD has this as well so that you don't need to add
>> individual devices.
>
> This is what am currently doing. From what I can see, linux correctly
> detects the range but I will have a look at it again before sending
> the next version.
>
> There was another issue raised by Michael about denying VFIO in case a
> user requests for IOMMU support. I did look at this but since VFIO is
> started with '-device' I didn't find a way to deny it in case of IOMMU
> support except by parsing command line arguments which turned out to
> be a bit ugly.
>
> We could exclude VFIO from translation by IOMMU by excluding it from
> the scope descriptions but am not quite sure this will remedy all the
> problems relating to VFIO and IOMMU. This will also require the device
> scope to explicitly list all the devices.
You may also try listing everything "up to" VFIO, then everything 
"after" the VFIO, I guess.

Valentine