From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [iGVT-g] [vfio-users] [PATCH v3 00/11] igd passthrough chipset tweaks Date: Tue, 02 Feb 2016 07:38:11 -0700 Message-ID: <1454423891.10542.16.camel@redhat.com> References: <1451994098-6972-1-git-send-email-kraxel@redhat.com> <1454009759.7183.7.camel@redhat.com> <1454051359.28516.28.camel@redhat.com> <1454090373.23148.11.camel@redhat.com> <003AAFE53969E14CB1F09B6FD68C3CD47BB681B7@ORSMSX106.amr.corp.intel.com> <1454262132.10542.1.camel@redhat.com> <003AAFE53969E14CB1F09B6FD68C3CD47BB6B475@ORSMSX106.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <003AAFE53969E14CB1F09B6FD68C3CD47BB6B475@ORSMSX106.amr.corp.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org To: "Kay, Allen M" , Gerd Hoffmann , David Woodhouse Cc: "igvt-g@ml01.01.org" , "xen-devel@lists.xensource.com" , Eduardo Habkost , Stefano Stabellini , "qemu-devel@nongnu.org" , Cao jin , "vfio-users@redhat.com" List-Id: xen-devel@lists.xenproject.org On Tue, 2016-02-02 at 00:04 +0000, Kay, Allen M wrote: >=C2=A0 > > -----Original Message----- > > From: Alex Williamson [mailto:alex.williamson@redhat.com] > > Sent: Sunday, January 31, 2016 9:42 AM > > To: Kay, Allen M; Gerd Hoffmann; David Woodhouse > > Cc: igvt-g@ml01.01.org; xen-devel@lists.xensource.com; Eduardo Habkos= t; > > Stefano Stabellini; qemu-devel@nongnu.org; Cao jin; vfio- > > users@redhat.com > > Subject: Re: [iGVT-g] [vfio-users] [PATCH v3 00/11] igd passthrough c= hipset > > tweaks > >=C2=A0 > > On Sat, 2016-01-30 at 01:18 +0000, Kay, Allen M wrote: > > >=C2=A0 > > > > -----Original Message----- > > > > From: iGVT-g [mailto:igvt-g-bounces@lists.01.org] On Behalf Of Al= ex > > > > Williamson > > > > Sent: Friday, January 29, 2016 10:00 AM > > > > To: Gerd Hoffmann > > > > Cc: igvt-g@ml01.01.org; xen-devel@lists.xensource.com; Eduardo > > > > Habkost; Stefano Stabellini; qemu-devel@nongnu.org; Cao jin; vfio= - > > > > users@redhat.com > > > > Subject: Re: [iGVT-g] [vfio-users] [PATCH v3 00/11] igd passthrou= gh > > > > chipset tweaks > > > >=C2=A0 > > > > Do guest drivers depend on IGD appearing at 00:02.0?=C2=A0=C2=A0I= 'm currently > > > > testing for any Intel VGA device, but I wonder if I should only b= e > > > > enabling anything opregion if it also appears at a specific addre= ss. > > > >=C2=A0 > > >=C2=A0 > > > No.=C2=A0=C2=A0Both Windows and Linux IGD driver should work at any= PCI slot.=C2=A0=C2=A0We > > have seen 0:5.0 in the guest and the driver works. > >=C2=A0 > > Thanks Allen.=C2=A0=C2=A0Another question, when I boot a VM with an a= ssigned HD > > P4000 GPU, my console stream with IOMMU faults, like: > >=C2=A0 > > DMAR: DMAR:[DMA Write] Request device [00:02.0] fault addr 9fa30000 > > DMAR: DMAR:[DMA Write] Request device [00:02.0] fault addr 9fa30000 > > DMAR: DMAR:[DMA Write] Request device [00:02.0] fault addr 9fa30000 > > DMAR: DMAR:[DMA Write] Request device [00:02.0] fault addr 9fa30000 > > DMAR: DMAR:[DMA Write] Request device [00:02.0] fault addr 9fa30000 > >=C2=A0 > > All of these fall within the host RMRR range for the device: > >=C2=A0 > > DMAR: Setting RMRR: > > DMAR: Setting identity map for device 0000:00:02.0 [0x9f800000 - 0xaf= 9fffff] >=C2=A0 > Hi Alex, >=C2=A0 > Do you configure IGD as primary or secondary display in your KVM setup?= =C2=A0=C2=A0=C2=A0If primary, are you running Intel vBIOS as part of gues= t boot? >=C2=A0 > On BDW/SKL systems, we have started to configure IGD as secondary and Q= EMU VGA and primary.=C2=A0=C2=A0In this setup, we are no longer running v= BIOS in the guest which avoids some complications.=C2=A0=C2=A0vBIOS uses > stolen memory for display buffers which requires RMRR mapping.=C2=A0=C2= =A0We have been using similar setup (IGD as secondary) on other hyperviso= rs and have not seen IOMMU faults. >=C2=A0 > I will setup a KVM configuration on my SKL and see if I can duplicate y= our problem here.=C2=A0=C2=A0=C2=A0I will try to call into Don's Thursday= meeting to discuss this (I'm on call for jury duty this week).=C2=A0=C2=A0= I > will give you a heads up on Wednesday evening. Hi Allen, I'm currently trying to run as primary, but I don't get any output until well into the guest boot, so clearly the Intel vBIOS is not happy, regardless of whether I provide VGA region access.=C2=A0=C2=A0When I try = to run as secondary I don't get any output at all on the assigned device and the FC23 Live CD I'm booting doesn't appear to see the IGD output.=C2=A0=C2=A0= I've only just started playing with actually using it though, so perhaps I haven't dialed it in just yet.=C2=A0=C2=A0I will note though that the DMA= R faults are well after the vBIOS would have been run, I see the i915 driver reads the stolen memory base from config register 0x5c.=C2=A0=C2=A0Emulat= ing this register as returning 0x0 avoids the DMAR faults and fixes corruption of the framebuffer, so this doesn't appear to be exclusive to the vBIOS. Regardless of which we intend to support, device assignment is an advanced topic for most users and I think we need to do something to protect users from having their VM memory stomped on by an IGD device writing framebuffer data over RAM.=C2=A0=C2=A0Thanks, Alex