From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: ioeventfd question
Date: Fri, 27 May 2011 11:30:16 +0300
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Cc: kvm <kvm@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
	Pekka Enberg <penberg@kernel.org>,
	Asias He <asias.hejun@gmail.com>,
	Prasad Joshi <prasadjoshi124@gmail.com>,
	Cyrill Gorcunov <gorcunov@gmail.com>
To: Sasha Levin <levinsasha928@gmail.com>
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On 05/26/2011 10:03 PM, Sasha Levin wrote:
> Hi Avi,
>
> I'm working on adding ioeventfd support into tools/kvm/.
> Currently the implementation creates ioeventfd entries at the
> 'VIRTIO_PCI_QUEUE_NOTIFY' of each device and waits on all of them using
> epoll().
> The basics are working - when IO is triggered I receive a notification
> using the event instead of an exit.
>
> I couldn't find a way to retrieve the value written to the PIO port -
> the guest memory at that location doesn't change, 'reading' the event
> just returns 1 (as expected) and I couldn't find anything else which
> might suggest what value was written to the PIO port.

You can use KVM_IOEVENTFD_FLAG_DATAMATCH for that.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.