From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 0/16 v6] PCI: Linux kernel SR-IOV support Date: Sun, 09 Nov 2008 21:37:20 +0200 Message-ID: <49173BF0.5050506@redhat.com> References: <20081106154351.GA30459@kroah.com> <894107.30288.qm@web45108.mail.sp1.yahoo.com> <20081106164919.GA4099@kroah.com> <0199E0D51A61344794750DC57738F58E5E26F996C4@GVW1118EXC.americas.hpqcorp.net> <20081106180354.GA17429@kroah.com> <4916DB16.2040709@redhat.com> <20081109192505.GA3091@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081109192505.GA3091@kroah.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Greg KH Cc: "randy.dunlap@oracle.com" , "grundler@parisc-linux.org" , "Chiang, Alexander" , "matthew@wil.cx" , "linux-pci@vger.kernel.org" , "rdreier@cisco.com" , "linux-kernel@vger.kernel.org" , "jbarnes@virtuousgeek.org" , "virtualization@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "mingo@elte.hu" List-Id: virtualization@lists.linuxfoundation.org Greg KH wrote: > On Sun, Nov 09, 2008 at 02:44:06PM +0200, Avi Kivity wrote: > >> Greg KH wrote: >> >>> It's that "second" part that I'm worried about. How is that going to >>> happen? Do you have any patches that show this kind of "assignment"? >>> >>> >>> >> For kvm, this is in 2.6.28-rc. >> > > Where? I just looked and couldn't find anything, but odds are I was > looking in the wrong place :( > > arch/x86/kvm/vtd.c: iommu integration (allows assigning the device's memory resources) virt/kvm/irq*: interrupt redirection (allows assigning the device's interrupt resources) the rest (pci config space, pio redirection) are in userspace. >> Note there are two ways to assign a device to a guest: >> >> - run the VF driver in the guest: this has the advantage of best >> performance, but requires pinning all guest memory, makes live migration a >> tricky proposition, and ties the guest to the underlying hardware. >> > > Is this what you would prefer for kvm? > > It's not my personal preference, but it is a supported configuration. For some use cases it is the only one that makes sense. Again, VF-in-guest and VF-in-host both have their places. And since Linux can be both guest and host, it's best if the VF driver knows nothing about SR-IOV; it's just a pci driver. The PF driver should emulate anything that SR-IOV does not provide (like missing pci config space). -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.