From mboxrd@z Thu Jan 1 00:00:00 1970 From: Akio Takebe Subject: Re: [Q] Is qemu used when we use VTd? Date: Fri, 12 Sep 2008 12:25:17 +0900 Message-ID: <48C9E11D.9060006@jp.fujitsu.com> References: <48C8F6F2.20305@jp.fujitsu.com> <48C90572.6020206@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=gb2312 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Tian, Kevin" Cc: xen-devel@lists.xensource.com, Jean Guyader List-Id: xen-devel@lists.xenproject.org Tian, Kevin wrote: >> From: Akio Takebe >> Sent: 2008=C4=EA9=D4=C211=C8=D5 19:48 >> >> Can we directly use MMCONFIG for PCI-Express card=20 >> pass-throughed by VT-d on HVM? >> >=20 > You can't. MMCONFIG in no sense vary from old I/O port > style, as just a means to access PCI configuration space. > Note that PCI configuration space access has to be trapped > as it determines which devices, and also config space > content to be observed by HVM guest. Normally you'd need > some virtualization on config space content, such as BARs. > Thus even by presenting MMCONFIG capability to HVM > guest, you still need trap those access falling in that range. I suspect MMCONFIG is needed to access Extended PCI configuration space of PCI-Express. Probably PCI-Express card can work without those access. But we can't use full features of PCI-Express cards, right? Best Regards, Akio Takebe