linux-kernel - Re: [kvm-devel] [PATCH 3/3] virtio PCI device

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: <473325EB.5090907@us.ibm.com>
Date:	Thu, 08 Nov 2007 09:06:19 -0600
From:	Anthony Liguori <aliguori@...ibm.com>
To:	Avi Kivity <avi@...ranet.com>
CC:	linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...ycorp.com.au>,
	virtualization@...ts.osdl.org, kvm-devel@...ts.sourceforge.net
Subject: Re: [kvm-devel] [PATCH 3/3] virtio PCI device

Avi Kivity wrote:
> If a pci device is capable of dma (or issuing interrupts), it will be 
> useless with pv pci.

Hrm, I think we may be talking about different things.  Are you thinking 
that the driver I posted allows you to do PCI pass-through over virtio?  
That's not what it is.

The driver I posted is a virtio implementation that uses a PCI device.  
This lets you use virtio-blk and virtio-net under KVM.  The alternative 
to this virtio PCI device would be a virtio transport built with 
hypercalls like lguest has.  I choose a PCI device because it ensured 
that each virtio device showed up like a normal PCI device.

Am I misunderstanding what you're asking about?

Regards,

Anthony Liguori

>
>>>  I think that with Amit's pvdma patches you
>>> can support dma-capable devices as well without too much fuss.
>>>   
>>
>> What is the use case you're thinking of?  A semi-paravirt driver that 
>> does dma directly to a device?
>
> No, an unmodified driver that, by using clever tricks with dma_ops, 
> can do dma directly to guest memory.  See Amit's patches.
>
> In fact, why do a virtio transport at all?  It can be done either with 
> trap'n'emulate, or by directly mapping the device mmio space into the 
> guest.
>
>
> (what use case are you considering? devices without interrupts and 
> dma? pci door stoppers?)
>

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/