Re: [Qemu-devel] [V12 0/4] AMD IOMMU

[David Kiarie]

On Wed, Jun 15, 2016 at 5:26 PM, Eduardo Habkost <address@hidden> wrote:
> On Wed, Jun 15, 2016 at 03:21:48PM +0300, David Kiarie wrote:
>> Hi all,
>>
>> This patchset adds basic AMD IOMMU emulation support to Qemu.
>>
>> Changes since V11
>>    -AMD IOMMU is not started with -device amd-iommu (with a dependency on 
>> Marcel's patches).
>>    -IOMMU commands are represented using bitfields which is less error prone 
>> and more readable[Peter]
>>    -Changed from debug fprintfs to tracing[Jan]
>
> What were the issues that required the sysbus+PCI code you sent
> previously? How did you address them in this series?

Short answer: Those issues are not present in this patch.

Long answer: The sysbus + PCI code is necessary for interrupt
remapping to be implemented(it could also be done without sysbus + PCI
code but that wouldn't be in line with the Intel IOMMU interrupt
remapping code, which is already on the list). The idea is that X86
IOMMUs should have a base class that implements common code. It was
decided that this class should be a SysBusDev(which works perfectly
with Intel IOMMU) but not with AMD IOMMU which has PCI properties. I
had to find a way to provide for the PCI properties once I inherit
from Intel IOMMU.

In this patchset, I have not inherited from the base class(it's not
merged yet) and even if it was merged I'd prefer to only use the
SysBus + PCI code when necessary(when I work on interrupt remapping)
so as to avoid delaying this patchset further.


>
> --
> Eduardo