Re: [Qemu-devel] VFIO VGA test branches

[Maik Broemme]

Hi Knut,

Knut Omang <address@hidden> wrote:
> 
> On Mon, 2013-05-13 at 16:23 -0600, Alex Williamson wrote:
> > On Mon, 2013-05-13 at 22:55 +0200, Knut Omang wrote:
> > > Hi all,
> > > 
> > > Perfect timing from my perspective, thanks Alex!
> > > 
> > > I spent the better part of the weekend testing your branches on a new 
> > > system 
> > > I just put together for this purpose, results below..
> > > 
> > > On Fri, 2013-05-03 at 16:56 -0600, Alex Williamson wrote:
> > > ...
> > > > git://github.com/awilliam/linux-vfio.git vfio-vga-reset
> > > > git://github.com/awilliam/qemu-vfio.git vfio-vga-reset
> > > 
> > > System setup: 
> > > 
> > > - Fedora 18 on
> > > - Gigabyte Z77X-UD5H motherboard
> > > - Intel Core i7 3770 (Ivy bridge w/integrated graphics)
> > > - 2 discrete graphics cards:
> > > 
> > > lspci | egrep 'VGA|Audio'
> > > 00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v2/3rd 
> > > Gen Core processor Graphics Controller (rev 09)
> > > 00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset 
> > > Family High Definition Audio Controller (rev 04)
> > > 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI 
> > > Caicos [Radeon HD 6450]
> > > 01:00.1 Audio device: Advanced Micro Devices [AMD] nee ATI Caicos HDMI 
> > > Audio [Radeon HD 6400 Series]
> > > 02:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI 
> > > Cape Verde PRO [Radeon HD 7700 Series]
> > > 02:00.1 Audio device: Advanced Micro Devices [AMD] nee ATI Cape 
> > > Verde/Pitcairn HDMI Audio [Radeon HD 7700/7800 Series]
> > > 
> > > Short summary:
> > > 
> > > - Once I got past a few time consuming obstacles explained below
> > >    - the graphics part of the graphics/hdmi audio passthrough seems to 
> > > work perfect
> > >      on both discrete graphics cards 
> > >      (though so far only one at at time and with some minor issues, see 
> > > below)
> > >    - no success with the hdmi audio yet (ideas for further investigation 
> > > appreciated!)
> > 
> > I've had hdmi audio working with an HD7850, but only in Windows (7) and
> > it was using legacy interrupts for some reason instead of MSI.  I wonder
> > if Liux guests might work with snd_hda_intel.enable_msi=0.  I'm not sure
> > what's wrong with MSI, but it seems to be new with the PCI bus reset
> > support.
> 
> In my first tries, Windows were just using a generic
> VGA driver, which still seems to work perfect with reboots and everything 
> and in full screen resolution (1920x1200).
> However after installing the Catalyst AMD driver stack, upon boot
> Windows 7 now consequently get a BSOD from the graphics driver
> with the message:
> 
> "Attempt to reset the display driver and recover from timeout failed"
> - a picture of the BSOD screen attached.
> 
> I attach the corresponding vfio log where I added some timing code to
> make it easier to see when the BSOD happens (with 2 seconds of silence
> in the log before the VM reboots, I believe this is at 09:28:32-34 in
> the log.
> 
> Similar behaviour both just after reboot/power cycle of the host and
> subsequent VM boot attempts.
> 
> This is still with the HD7700 as passed through device, but after a
> motherboard firmware upgrade (to F14) which did not seem to affect the
> observed behaviour on Windows prior to Catalyst install or with Linux
> guest, neither did it fix the bug in selecting primary devices as I 
> was hoping for.
> 
> Let me know if you have ideas for further debugging this,
> 

I had a similar problem a couple of days ago and posted it in this list.
I got similar BSOD and tested already the following configurations:

1) machine: q35 / kvm: yes / vga: none   / x-vga: on  = qemu freeze
2) machine: q35 / kvm: no  / vga: none   / x-vga: on  = qemu freeze
   (with errors below)
3) machine: q35 / kvm: yes / vga: none   / x-vga: off = qemu runs with
   100% CPU due to no VGA init (no picture)
4) machine: q35 / kvm: yes / vga: cirrus / x-vga: off = qemu runs with
   BOSD on loading atikmpag.sys
5) machine: pc  / kvm: yes / vga: cirrus / x-vga: off = qemu runs fine

However I've re-run the BSOD case already with the following branches
from Alex:

git://github.com/awilliam/linux-vfio.git vfio-vga-reset
git://github.com/awilliam/qemu-vfio.git vfio-vga-reset

Also with latest seabios and it worked so far. No more BSOD and reboot
of VM was also possible without suspend / resume the host between.

> Thanks,
> 
> Knut
> 
> > > - Contrary to address@hidden I had no success with using pci-assign for 
> > > VGA
> > >   with a standard fedora 18 kernel and fairly recent qemu, nor with your 
> > > branches, 
> > > 
> > > Details:
> > > 
> > > - I started off with the required kernel parameter 'intel_iommu=on' + 
> > > necessary parameters for disabling radeon
> > >    (radeon.modeset=0 rd.driver.blacklist=radeon) using the integrated 
> > > graphics as primary display
> > >    - this caused the system to freeze (with color artifacts on the 
> > > console)
> > > 
> > > - In my naivity and because of the "i" in ifgx I tried both with 
> > >   'intel_iommu=ifgx_off' and then 'intel_iommu=on,igfx_off' 
> > >   and a full set of combinations of vfio, cards, kernels and pci-assign 
> > > before I suspected 
> > >   that iommu support was turned off for **all** graphics cards with 
> > > igfx_off
> > 
> > I'm not sure why this is, looks like the code only tries to turn it off
> > when only graphics is under the remapping device.  We'd probably need to
> > see the DMAR to know more (/sys/firmware/acpi/tables/DMAR).
> > 
> > > - The solution was to have integrated graphics turned off in the BIOS, 
> > > and 'intel_iommu=on':
> > > 
> > > - iommu groups:
> > > 
> > > ls -l /sys/bus/pci/devices/0000:01:00.0/iommu_group/devices
> > > total 0
> > > lrwxrwxrwx 1 root root 0 May 11 08:55 0000:00:01.0 -> 
> > > ../../../../devices/pci0000:00/0000:00:01.0
> > > lrwxrwxrwx 1 root root 0 May 11 08:55 0000:00:01.1 -> 
> > > ../../../../devices/pci0000:00/0000:00:01.1
> > > lrwxrwxrwx 1 root root 0 May 11 08:55 0000:01:00.0 -> 
> > > ../../../../devices/pci0000:00/0000:00:01.0/0000:01:00.0
> > > lrwxrwxrwx 1 root root 0 May 11 08:55 0000:01:00.1 -> 
> > > ../../../../devices/pci0000:00/0000:00:01.0/0000:01:00.1
> > > lrwxrwxrwx 1 root root 0 May 11 08:55 0000:02:00.0 -> 
> > > ../../../../devices/pci0000:00/0000:00:01.1/0000:02:00.0
> > > lrwxrwxrwx 1 root root 0 May 11 08:55 0000:02:00.1 -> 
> > > ../../../../devices/pci0000:00/0000:00:01.1/0000:02:00.1
> > > 
> > > - eg. both the VGA/HDMI Audio pairs + the two root ports they are plugged 
> > > into are in the same group:
> > 
> > Ick.  Intel has been pretty good about advertising ACS support on their
> > root ports.  I wonder if this is an oversight or if they are actually
> > not isolated from each other.
> > 
> > > # lspci -n
> > > ...
> > > 01:00.0 0300: 1002:683f
> > > 01:00.1 0403: 1002:aab0
> > > 02:00.0 0300: 1002:6779
> > > 02:00.1 0403: 1002:aa98
> > > ...
> > > 
> > > modprobe vfio_pci
> > > echo 0000:01:00.1 > /sys/bus/pci/devices/0000\:01\:00.1/driver/unbind
> > > echo 0000:02:00.1 > /sys/bus/pci/devices/0000\:02\:00.1/driver/unbind
> > > echo 1002 683f > /sys/bus/pci/drivers/vfio-pci/new_id
> > > echo 1002 aab0 > /sys/bus/pci/drivers/vfio-pci/new_id
> > > echo 1002 6779 > /sys/bus/pci/drivers/vfio-pci/new_id
> > > echo 1002 aa98 > /sys/bus/pci/drivers/vfio-pci/new_id
> > > 
> > > # lsusb 
> > > ...
> > > Bus 001 Device 008: ID 046d:c315 Logitech, Inc. Classic New Touch Keyboard
> > > Bus 001 Device 004: ID 046d:c05b Logitech, Inc. M-U0004 810-001317 [B110 
> > > Optical USB Mouse]
> > > ...
> > > 
> > > - I also applied your suggested patch to the quirk function in VFIO (see 
> > > below)
> > > 
> > > - Here is a (trimmed for readability) command line I successfully used to 
> > > boot from the Windows 7 install DVD, 
> > >   notice the cd and disk device descriptions and the bus parameter - I 
> > > struggled a while with that 
> > >   until I came across a comment by Gerd Hoffmann here: 
> > > https://bugzilla.redhat.com/show_bug.cgi?id=922670 (Thanks, Gerd!)
> > > 
> > > 
> > > qemu-kvm -M q35 \
> > >   -nodefconfig -readconfig $SRC/qemu/docs/q35-chipset.cfg \
> > >   -device 
> > > vfio-pci,host=2:00.0,x-vga=on,multifunction=on,bus=ich9-pcie-port-1,addr=0.0
> > >  \
> > >   -device vfio-pci,host=2:00.1,bus=ich9-pcie-port-1,addr=0.1 \
> > >   -L $SRC/seabios/out/ -L $SRC/qemu/pc-bios \
> > >   -vga none -nographic -cpu host -rtc base=localtime -k no -m 8192 -smp 2 
> > > \
> > >   -drive file=/dev/sr0,index=2,media=cdrom,id=cd \
> > >   -drive file=ivm03.img,index=0,media=disk,id=ivm03 \
> > >   -device ide-drive,drive=ivm03,bus=ide.0 \
> > >   -device ide-cd,drive=cd,bus=ide.1 \
> > >   -net nic,vlan=0,model=virtio -net tap,vlan=0 \
> > >   -enable-kvm \
> > >   -device usb-host,hostbus=1,hostaddr=8 \
> > >   -device usb-host,hostbus=1,hostaddr=4
> > > 
> > > - Both the graphics card seemshould really support ACS on s to have a rom 
> > > but only the HD6450 let itself to "scraping". 
> > 
> > Did you try scraping the HD6450 while the HD7700 was the boot VGA and
> > vica versa?  The boot VGA ROM is handled in a special way and what you
> > really get is the shadow copy, which isn't what we want.
> > 
> > > Anyway, supplying it to vfio did not seem to make any difference.
> > > 
> > > find /sys -name rom
> > > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/rom
> > > /sys/devices/pci0000:00/0000:00:01.1/0000:02:00.0/rom
> > > ...
> > > 
> > > Some observations and remaining unresolved issues:
> > > 
> > > - VFIO patch:
> > >   Initially (while still running with igfx_off) I observed exactly the 
> > > same behaviour as address@hidden
> > >   reported a while ago: With vfio_pci debug enabled, vfio_pci ended up 
> > > spinning with repeated calls to
> > >   vfio_ati_3c3_quirk_read and repeated logs: 
> > >     vfio: vfio_vga_read(0x3c3, 1) = 0x0
> > >   I patched up accordingly with 
> > > 
> > > 
> > > diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> > > index da0e5f9..a361d06 100644
> > > --- a/hw/misc/vfio.c
> > > +++ b/hw/misc/vfio.c
> > > @@ -1291,7 +1291,7 @@ static uint64_t vfio_ati_3c3_quirk_read(void 
> > > *opaque,
> > >      uint64_t data = vfio_vga_read(&vdev->vga.region[QEMU_PCI_VGA_IO_HI],
> > >                                    addr + quirk->data.base_offset, size);
> > >  
> > > -    if (data == quirk->data.address_match) {
> > > +    if (1 || data == quirk->data.address_match) {
> > >          data = vfio_pci_read_config(&vdev->pdev, 
> > > quirk->data.address_val, size);
> > >          DPRINTF("%s(0x3c3, 1) = 0x%"PRIx64"\n", __func__, data);
> > >      }
> > > 
> > > 
> > >   This of course did not help much until I actually got the iommu 
> > >   enabled for the radeons (similar "repeated patters" as deniv reported)
> > >   but what I have observed after I got it working is that if 
> > >   I disable the patch above, things are not that well: the Fedora VM 
> > >   comes up with VGA and the Fedora boot screen, then goes blank when 
> > >   switching to X.
> > 
> > Hmm, I think we'd probably have better luck making that unconditional
> > until we have reason to do otherwise.
> > 
> > > - The fact that the iommu group now extends across all my available 
> > > graphics 
> > >   devices now makes it difficult to  get the radeon (or catalyst) driver 
> > > use to 
> > >   the other card since the vfio_pci driver needs to hold it.
> > >   Not a complete showstopper since the vesa driver comes up with 
> > > 1024x768..
> > >   Might it be a good idea to have an override option (exception list or 
> > > similar?) 
> > >   to allow the vfio_pci to be less restrictive about owning the whole 
> > > group 
> > >    - allow functionality over security in such case? This of course is 
> > > further complicated
> > >   by the need for graphics drivers to be disabled/enabled already at the 
> > > kernel prompt..
> > 
> > We have a quirk in the kernel that enables us to witelist devices, but
> > yes, there is no flexibility in this w/o modifying the code and
> > rebuilding.  (see drivers/pci/quirks.c:pci_dev_acs_enabled and follow
> > the example above w/ pci_dev_dma_source - function can just return 1)
> > 
> > > - There seems to be a bug in the (version F8) UEFI BIOS on the 
> > > motherboard, 
> > >   The BIOS offers (undocumented) a full range of selections of which PCIe 
> > >   (or PCIe 1x) graphics card to use as primary, but any other selection 
> > >   than the first PCIe 16x slot has no effect and the motherboard reverts 
> > >   to the first slot, so to be able to test both cards, I had to put the 
> > > card under test
> > >   into the second (8x) PCIe slot. I am waiting for feedback from Gigabyte 
> > > on possible 
> > >   fixes for this in newer BIOSes.
> > > 
> > > - The ultimate goal is to try to consolidate some older Windows desktops 
> > > as "seats" 
> > >   on the new system, using the discrete graphics with HDMI/Displayport 
> > > audio. 
> > >   With the HD7700 moved to the second PCIe slot I tested both Windows and 
> > >   Linux guests to try to get some sound through the HDMI audio device. 
> > >   Windows complains that no usable device is available. On Linux (Fedora 
> > > 18, KDE desktop), 
> > >   the system settings -> multimedia dialogue never opens up which seems 
> > > to indicate that 
> > >   PulseAudio has problems communicating with the passed through device 
> > > (?), 
> > >   any hints/pointers here appreciated. From the vfio log it seems at least
> > >   config space is accessed ok.
> > > 
> > > - There also seems to be issues with radeon and intel_iommu=on - if I try 
> > >   to enable modesetting and normal X support for the radeon cards, X 
> > > fails to start.
> > > 
> > > - It would be nice if the integrated graphics could be used as the host 
> > > primary display - 
> > >   I would be happy if someone has any hints as to if/how the ifgx_off 
> > > option 
> > >   could be extended/modified to only affect iommu operation on selected 
> > > device(s),
> > >   if at all possible..
> > 
> > Let's see what we can discover from your DMAR.  Also send along sudo
> > lspci -vvv.  Thanks,
> > 
> > Alex
> > 
> 
> 

--Maik