netdev - Re: [Alacrityvm-devel] [PATCH v3 3/6] vbus: add a "vbus-proxy" bus model for vbus

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4A8ADC09.3030205@redhat.com>
Date:	Tue, 18 Aug 2009 19:51:21 +0300
From:	Avi Kivity <avi@...hat.com>
To:	"Ira W. Snyder" <iws@...o.caltech.edu>
CC:	"Michael S. Tsirkin" <mst@...hat.com>,
	Gregory Haskins <gregory.haskins@...il.com>,
	kvm@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	alacrityvm-devel@...ts.sourceforge.net,
	Anthony Liguori <anthony@...emonkey.ws>,
	Ingo Molnar <mingo@...e.hu>,
	Gregory Haskins <ghaskins@...ell.com>
Subject: Re: [Alacrityvm-devel] [PATCH v3 3/6] vbus: add a "vbus-proxy" bus
 model for vbus_driver objects

On 08/18/2009 06:53 PM, Ira W. Snyder wrote:
> So, in my system, copy_(to|from)_user() is completely wrong. There is no
> userspace, only a physical system. In fact, because normal x86 computers
> do not have DMA controllers, the host system doesn't actually handle any
> data transfer!
>    

In fact, modern x86s do have dma engines these days (google for Intel 
I/OAT), and one of our plans for vhost-net is to allow their use for 
packets above a certain size.  So a patch allowing vhost-net to 
optionally use a dma engine is a good thing.

> I used virtio-net in both the guest and host systems in my example
> virtio-over-PCI patch, and succeeded in getting them to communicate.
> However, the lack of any setup interface means that the devices must be
> hardcoded into both drivers, when the decision could be up to userspace.
> I think this is a problem that vbus could solve.
>    

Exposing a knob to userspace is not an insurmountable problem; vhost-net 
already allows changing the memory layout, for example.

-- 
error compiling committee.c: too many arguments to function

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html