Hi, I have had fun recently trying to get vega gpu passthru working. After a lot of testing and some kernel patching I would say: 1) if you want vega gpu reset working, use kernel 5.1.5 or above in the guest as well as the host. 2) if you want passthru working instead of a blank screen at vm start, use OVMF efi instead of seabios. 3) you may or may not need a vfio patch that stops the graphics card resizing the BAR.
Kind regards James On Mon, 3 Jun 2019, 22:40 Micah Morton, <mort...@chromium.org> wrote: > Hi Alex, > > Could you remind me whether there is a minimum recommended kernel > version to be running in the VM guest when doing GPU passthrough? > > I'm fine running 4.14 in the host, but was looking to see if I could > run 4.4 in the guest and couldn't remember if it is advised to use a > newer kernel in the guest or if there is any reason to have the guest > kernel match the host kernel version? > > On Wed, May 29, 2019 at 10:00 AM Micah Morton <mort...@chromium.org> > wrote: > > > > Ah my bad. Just realized I was using my own copy of SeaBIOS that I had > > built. When I use the copy from qemu-3.0.0/pc-bios/bios-256k.bin I see > > the i915 driver finding the OpRegion: > > [ 0.269341] in i915_driver_init_hw > > [ 0.269374] [drm] Memory usable by graphics device = 4096M > > [ 0.269585] in intel_opregion_setup > > [ 0.269600] graphic opregion physical addr: 0x7fffe000 > > > > Still working on getting the screen to light up > > > > On Wed, May 29, 2019 at 9:44 AM Alex Williamson > > <alex.william...@redhat.com> wrote: > > > > > > On Wed, 29 May 2019 09:25:59 -0700 > > > Micah Morton <mort...@chromium.org> wrote: > > > > > > > So as I mentioned, the ChromeOS firmware writes the location of the > > > > OpRegion to the ASLS PCI config register > > > > ( > https://github.com/coreboot/coreboot/blob/master/src/drivers/intel/gma/opregion.c#L88 > ). > > > > The i915 driver then gets the address for the OpRegion from that > > > > register here: > https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/i915/intel_opregion.c#L910 > . > > > > This all works for Chrome OS, but when we run a VM with SeaBIOS the > > > > ASLS PCI config register doesn't get written with the location of the > > > > OpRegion.: > > > > [ 0.263640] in i915_driver_init_hw (I added this) > > > > ... > > > > [ 0.263922] in intel_opregion_setup (and this) > > > > [ 0.263954] graphic opregion physical addr: 0x0 <-- This is > > > > supposed to point to the OpRegion, not be zero. > > > > [ 0.263954] ACPI OpRegion not supported! > > > > ... > > > > [ 0.267727] Failed to find VBIOS tables (VBT) > > > > > > > > I'm also not sure if the OpRegion is actually in VM memory or not. Do > > > > you think I need to find a way to put the OpRegion in VM memory as we > > > > have seen coreboot (Chrome OS firmware) do above? Or should using > > > > "x-igd-opregion=on" somehow ensure that the OpRegion makes it into VM > > > > memory? Clearly I at least need to find a way to set that ASLS PCI > > > > config register in the VM or modify the i915 driver that runs in the > > > > guest so it can find the OpRegion. > > > > > > In QEMU, vfio_pci_igd_opregion_init() adds the opregion to a fw_cfg > > > file "etc/igd-opregion" and makes the (virtual) ASLS register > > > writable. Then in SeaBIOS, any Intel vendor ID, PCI class VGA device > > > will trigger the intel_igd_setup() function, which looks for the fw_cfg > > > file, allocates space for it, and writes the GPA back to the ASLS > > > register. That's at least how it's supposed to work, which again > > > reminds me for the umpteenth time that x-igd-opregion only works with > > > SeaBIOS as OVMF has rejected this support in favor of an option ROM > > > based solution, which Intel never provided. I think you're using > > > SeaBIOS though so, so as long as that's not an ancient version it > > > should do the little dance here. The ASLS is writable though, we don't > > > do any write-once tricks, so something could blindly stomp on it. You > > > might enable logging in SeaBIOS, it will emit some spew for the > > > OpRegion support. You could also enable tracing to see the write of > > > the ASLS into QEMU. Thanks, > > > > > > Alex > > _______________________________________________ > vfio-users mailing list > vfio-users@redhat.com > https://www.redhat.com/mailman/listinfo/vfio-users >
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