Re: [Qemu-devel] [PATCH v2 00/13] IOMMU: Enable interrupt remapping for Intel IOMMU

[Jan Kiszka]

On 2016-04-13 00:27, Peter Xu wrote:
> On Mon, Apr 11, 2016 at 03:32:18PM +0300, Michael S. Tsirkin wrote:
>> On Mon, Apr 11, 2016 at 05:19:10PM +0800, Peter Xu wrote:
>>> v2 changes:
>>> - patch 1
>>>   - rename "int_remap" to "intr" in several places [Marcel]
>>>   - remove "Intel" specific words in desc or commit message, prepare
>>>     itself with further AMD support [Marcel]
>>>   - avoid using object_property_get_bool() [Marcel]
>>> - patch 5
>>>   - use PCI bus number 0xff rather than 0xf0 for the IOAPIC scope
>>>     definition. (please let me know if anyone knows how I can avoid
>>>     user using PCI bus number 0xff... TIA)
>>> - patch 11
>>>   - fix comments [Marcel]
>>> - all
>>>   - remove intr_supported variable [Marcel]
>>>
>>> This patchset provide very basic functionalities for interrupt
>>> remapping (IR) support of the emulated Intel IOMMU device.
>>>
>>> By default, IR is disabled to be better compatible with current
>>> QEMU. To enable IR, we can using the following command to boot a
>>> IR-supported VM with basic network (still do not support kvm-ioapic,
>>> so we need to specify kernel-irqchip=off here):
>>>
>>> $ qemu-system-x86_64 -M q35,iommu=on,intr=on,kernel-irqchip=off \
>>>      -enable-kvm -m 1024 -s \
>>>      -monitor telnet::3333,server,nowait \
>>>      -netdev user,id=user.0,hostfwd=tcp::5555-:22 \
>>>      -device virtio-net-pci,netdev=user.0 \
>>>      /var/lib/libvirt/images/vm1.qcow2
>>>
>>> When guest boots, we can verify whether IR enabled by grepping the
>>> dmesg like:
>>>
>>> address@hidden ~]# journalctl -k | grep "DMAR-IR"
>>> Feb 19 11:21:23 localhost.localdomain kernel: DMAR-IR: IOAPIC id 0 under 
>>> DRHD base  0xfed90000 IOMMU 0
>>> Feb 19 11:21:23 localhost.localdomain kernel: DMAR-IR: Enabled IRQ 
>>> remapping in xapic mode
>>>
>>> Currently only two devices are supported:
>>>
>>> - Emulated IOAPIC device
>>> - PCI Devices
>>>
>>> TODO List:
>>>
>>> - kvm-ioapic support
>>
>> This is probably a must. I don't think we can merge this
>> as long as it breaks kvm.
> 
> But kvm-ioapic might require modification to KVM as well. Do you
> think I should add kvm-ioapic into this series as well? Or can I
> first submit this part of work without kvm-ioapic (since this work
> is not related to KVM at all), then work on another one to support
> kvm-ioapic?

Just go for split irqchip. If we ever need support for in-kernel irqchip
is questionable.

Jan