From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@qumranet.com>
Subject: Re: [PATCH 1/1] direct mmio for passthrough - kernel
 part
Date: Tue, 01 Apr 2008 20:05:01 +0300
Message-ID: <47F26B3D.203@qumranet.com>
References: <1207050734-13166-1-git-send-email-benami@il.ibm.com>	<1207050734-13166-2-git-send-email-benami@il.ibm.com>
	<47F238D8.7040608@qumranet.com> <47F249C3.6000300@codemonkey.ws>
	<47F252D1.6060905@codemonkey.ws>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Cc: kvm-devel@lists.sourceforge.net, allen.m.kay@intel.com,
	andrea@qumranet.com, benami@il.ibm.com
To: Anthony Liguori <anthony@codemonkey.ws>
Return-path: <kvm-devel-bounces@lists.sourceforge.net>
In-Reply-To: <47F252D1.6060905@codemonkey.ws>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/kvm-devel>,
	<mailto:kvm-devel-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=kvm-devel>
List-Post: <mailto:kvm-devel@lists.sourceforge.net>
List-Help: <mailto:kvm-devel-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/kvm-devel>,
	<mailto:kvm-devel-request@lists.sourceforge.net?subject=subscribe>
Sender: kvm-devel-bounces@lists.sourceforge.net
Errors-To: kvm-devel-bounces@lists.sourceforge.net
List-Id: kvm.vger.kernel.org

Anthony Liguori wrote:
>>
>> Regardless of whether we can use /dev/mem, I think we should 
>> introduce a new char device anyway.  We only need to mmap() MMIO 
>> regions which are mapped by the PCI bus, presumably, the kernel 
>> should know about these mappings.  The driver should only allow 
>> mappings that are valid for a particular PCI device such that it 
>> cannot be abused to map arbitrary regions of memory into a guest.  
>> Bonus points if it can validate that there isn't a valid Linux driver 
>> loaded for the given PCI device.
>
> Which is apparently entirely unnecessary as we already have 
> /sys/bus/pci/.../region.  It's just a matter of checking if a vma is 
> VM_IO and then dealing with the subsequent reference counting issues 
> as Avi points out.
>

 From idea to working implementation in 38 minutes.  Congrats.


-- 
Any sufficiently difficult bug is indistinguishable from a feature.


-------------------------------------------------------------------------
Check out the new SourceForge.net Marketplace.
It's the best place to buy or sell services for
just about anything Open Source.
http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace