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Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390.
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390. |
Date: |
Tue, 26 Feb 2013 12:54:00 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 |
On 26/02/13 12:18, Michael S. Tsirkin wrote:
> On Tue, Feb 26, 2013 at 01:04:21PM +0200, Michael S. Tsirkin wrote:
>> On Mon, Feb 25, 2013 at 04:27:45PM +0100, Cornelia Huck wrote:
>>> Here's the latest version of my patch series enabling ioeventfds
>>> on s390, again against kvm-next.
>>>
>>> Patches 1 and 2 (cleaning up initialization and exporting the virtio-ccw
>>> api) would make sense even independent of the ioeventfd enhancements.
>>>
>>> Patches 3-5 are concerned with adding a new type of ioeventfds for
>>> virtio-ccw notifications on s390. The naming is now hopefully clearer.
>>> We won't add ioeventfd support for the legacy s390-virtio transport.
>>>
>>> Please consider applying.
>>
>> I just had a thought: this makes us lookup the device on the bus
>> for each notification. It would be better to simply get the
>> device index from guest instead.
>>
>> We could validate that it matches the correct device,
>> if not - fallback to the current linear scan.
>>
>> We could return the index to guest for the next call.
>>
>> I know this needs guest changes but it's still not too late to
>> fix this for 3.9 guests so that we won't need to worry
>> about compatibility going forward.
>>
>> Hmm?
>
> And just to clarify, here's what I mean (BTW, why doesn't
> this code use the interfaces from kvm_para.h?)
> I think it's a good idea to merge this before 3.9 so we don't
> need to worry about legacy going forward.
>
> Completely untested, just to give you the idea.
Thinking more about it: Isnt the index on the kvm bus just an implementation
detail? In other words, what happens if we want to re-arrange the kvm io bus
to a tree like structure. Then the index becomes pretty much useless. Do we
really want to put such an internal thing into an interface?
CHristian
- [Qemu-devel] [PATCH v3 4/5] KVM: ioeventfd for virtio-ccw devices., (continued)
- [Qemu-devel] [PATCH v3 2/5] KVM: s390: Export virtio-ccw api., Cornelia Huck, 2013/02/25
- [Qemu-devel] [PATCH v3 3/5] KVM: Introduce KVM_VIRTIO_CCW_NOTIFY_BUS., Cornelia Huck, 2013/02/25
- Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390., Michael S. Tsirkin, 2013/02/26
- Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390., Michael S. Tsirkin, 2013/02/26
- Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390., Christian Borntraeger, 2013/02/26
- Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390., Michael S. Tsirkin, 2013/02/26
- Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390., Christian Borntraeger, 2013/02/27
Re: [Qemu-devel] [PATCH v3 0/5] kvm: Make ioeventfd usable on s390., Christian Borntraeger, 2013/02/26