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Re: [Qemu-ppc] [PATCH] spapr-pci: remove io ports workaround

From: Alexey Kardashevskiy
Subject: Re: [Qemu-ppc] [PATCH] spapr-pci: remove io ports workaround
Date: Wed, 11 Dec 2013 17:47:55 +1100
User-agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1

On 12/10/2013 06:47 PM, Greg Kurz wrote:
> On Tue, 10 Dec 2013 13:43:05 +1100
> Alexey Kardashevskiy <address@hidden> wrote:
>> On 12/10/2013 03:33 AM, Greg Kurz wrote:
>>> In the past, IO space could not be mapped into the memory address space
>>> so we introduced a workaround for that. Nowadays it does not look
>>> necessary so we can remove the workaround and make sPAPR PCI
>>> configuration simplier.
>>> This workaround has also an evil side effect with virtio devices:
>>> because all PHBs have their .io region at the same address, the devices
>>> get mapped in the .io-alias region of every PHB (AKA. mapped multiple
>>> times). This breaks the ioeventfd feature and causes qemu to abort()
>>> when running with KVM and asking for more than one PHB:
>>> $ qemu-system-ppc64 -machine type=pseries,accel=kvm -smp 1 -m 4G \
>>>   -hda /local/greg/images/fedora-be.qcow2 \
>>>   -device
>>> virtio-9p-pci,fsdev=fsdev0,mount_tag=share,bus=pci,ioeventfd=on \
>>> -fsdev local,security_model=none,id=fsdev0,path=$HOME/share1 \ -device
>>> spapr-pci-host-bridge,index=15 kvm_mem_ioeventfd_add: error adding
>>> ioeventfd: File exists Aborted
>>> This will prevent to use virtio and VFIO passthrough at the same time,
>>> since VFIO needs a dedicated PHB to work on ppc.
>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>> I have not seen this version yet so please remove me from "SOB". The patch
>> you replied to was eventually reworked and went to upstream as
>> 66aab867cedd2a2d81b4d64eff7c3e0f6f272bbf
> Hi Alex,
> I agree you have not seen this version yet... The patch I replied to was my
> primary source of inspiration and contains these bits, hence the SOB. 
> Anyway, the SOB is now removed until you decide to add one yourself. :)
>> This one might be correct too but I want to try this first :)
> Well, I hope it is. Please try it.

Yep. Tried. Looks good, did not break a thing as far as I can tell, even
VGA works :)

Signed-off-by: Alexey Kardashevskiy <address@hidden>


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