Hello folks,
A colleague and I are trying to get legacy passthrough to work with a HP
Probook
430 G4 in BIOS mode. This is part of a "bigger" pet project where we are
trying
to use legacy passthrough on all our laptop that have a working IOMMU and
compatible hardware. Ultimately, we trying to run a Windows 10 guest within
that
VM.
We've experienced a success using a same generation IGD (on Lenovo Thinkpad
X260) where we got legacy passthrough to work and that encouraged us to
push
things further. We're now asking for help because we can't seem to find how
to
get it to work on an HP Probook G4. Qemu is stuck when loading the VBIOS.
Here is the command line for starting the VM:
$ qemu-system-x86_64 -D /var/log/qemu.log \
-serial file:/root/serial.logs -monitor stdio \
-bios /root/seabios-debug.bin -smbios type=0 \
-m 6G -enable-kvm -machine pc,accel=kvm \
-rtc driftfix=slew,base=localtime \
-cpu
host,hv_relaxed,hv_reset,hv_vpindex,hv_runtime,hv_spinlocks=0x1fff,hv_vapic,hv_time,kvm=off
\
-smp sockets=1,cores=2,threads=2 \
-drive format=qcow2,file=/root/windows.qcow2,index=0,if=virtio \
-vga none -display none -device
vfio-pci,host=00:02.0,id=hostdev0,bus=pci.0,addr=0x02,romfile=/root/image.rom,x-igd-gms=1
\
-device
virtio-input-host-pci,evdev=/dev/input/by-path/platform-i8042-serio-0-event-kbd
\
-device
virtio-input-host-pci,evdev=/dev/input/by-path/platform-i8042-serio-3-event-mouse
\
-net nic,model=virtio,addr=0x14 -net user
The image.rom VBIOS image has been extracted from a firmware update for HP
laptop (using UEFI tool) and patched with rom-fixer. The firmware update is
confirmed to be compatible with this laptop (it applied without bricking
the
laptop). We also tried using VBIOS from other hardware, but qemu then
rejects it
("Turning on vga text mode console" error message).
We compiled a Seabios with a debug serial console and obtained the
following output:
Changing serial settings was 0/0 now 3/0
SeaBIOS (version rel-1.11.0-25-g5adc8bd)
BUILD: gcc: (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609 binutils: (GNU
Binutils for Ubuntu) 2.26.1
No Xen hypervisor found.
enabling shadow ram
RamSize: 0xc0000000 [cmos]
malloc preinit
Relocating init from 0x000d8160 to 0xbffada00 (size 75104)
malloc init
Found QEMU fw_cfg
QEMU fw_cfg DMA interface supported
Add romfile: etc/show-boot-menu (size=2)
Add romfile: etc/irq0-override (size=1)
Add romfile: etc/max-cpus (size=2)
Add romfile: etc/numa-cpu-map (size=32)
Add romfile: etc/numa-nodes (size=0)
Add romfile: bootorder (size=0)
Add romfile: etc/acpi/rsdp (size=36)
Add romfile: etc/acpi/tables (size=131072)
Add romfile: etc/boot-fail-wait (size=4)
Add romfile: etc/e820 (size=60)
Add romfile: etc/igd-bdsm-size (size=8)
Add romfile: etc/igd-opregion (size=8192)
Add romfile: etc/msr_feature_control (size=8)
Add romfile: etc/smbios/smbios-anchor (size=31)
Add romfile: etc/smbios/smbios-tables (size=387)
Add romfile: etc/system-states (size=6)
Add romfile: etc/table-loader (size=4096)
Add romfile: etc/tpm/log (size=0)
Add romfile: genroms/kvmvapic.bin (size=9216)
RamBlock: addr 0x0000000000000000 len 0x00000000c0000000 [e820]
RamBlock: addr 0x0000000100000000 len 0x00000000c0000000 [e820]
Moving pm_base to 0x600
init ivt
init bda
init bios32
init PMM
init PNPBIOS table
init keyboard
init mouse
init pic
math cp init
pci setup
=== PCI bus & bridge init ===
PCI: pci_bios_init_bus_rec bus = 0x0
=== PCI device probing ===
PCI probe
Found 14 PCI devices (max PCI bus is 00)
=== PCI new allocation pass #1 ===
PCI: check devices
=== PCI new allocation pass #2 ===
PCI: IO: c000 - c0ef
PCI: 32: 00000000c0000000 - 00000000fec00000
PCI: map device bdf=00:02.0 bar 4, addr 0000c000, size 00000040 [io]
PCI: map device bdf=00:08.0 bar 0, addr 0000c040, size 00000040 [io]
PCI: map device bdf=00:01.2 bar 4, addr 0000c080, size 00000020 [io]
PCI: map device bdf=00:05.0 bar 0, addr 0000c0a0, size 00000020 [io]
PCI: map device bdf=00:14.0 bar 0, addr 0000c0c0, size 00000020 [io]
PCI: map device bdf=00:01.1 bar 4, addr 0000c0e0, size 00000010 [io]
PCI: map device bdf=00:02.0 bar 0, addr fd000000, size 01000000 [mem]
PCI: map device bdf=00:14.0 bar 6, addr fe000000, size 00040000 [mem]
PCI: map device bdf=00:02.0 bar 6, addr fe040000, size 00010000 [mem]
PCI: map device bdf=00:06.0 bar 0, addr fe050000, size 00004000 [mem]
PCI: map device bdf=00:03.0 bar 1, addr fe054000, size 00001000 [mem]
PCI: map device bdf=00:04.0 bar 1, addr fe055000, size 00001000 [mem]
PCI: map device bdf=00:05.0 bar 1, addr fe056000, size 00001000 [mem]
PCI: map device bdf=00:07.0 bar 0, addr fe057000, size 00001000 [mem]
PCI: map device bdf=00:08.0 bar 1, addr fe058000, size 00001000 [mem]
PCI: map device bdf=00:14.0 bar 1, addr fe059000, size 00001000 [mem]
PCI: map device bdf=00:02.0 bar 2, addr e0000000, size 10000000
[prefmem]
PCI: map device bdf=00:03.0 bar 4, addr f0000000, size 00004000
[prefmem]
PCI: map device bdf=00:04.0 bar 4, addr f0004000, size 00004000
[prefmem]
PCI: map device bdf=00:05.0 bar 4, addr f0008000, size 00004000
[prefmem]
PCI: map device bdf=00:08.0 bar 4, addr f000c000, size 00004000
[prefmem]
PCI: map device bdf=00:14.0 bar 4, addr f0010000, size 00004000
[prefmem]
PCI: init bdf=00:00.0 id=8086:1237
PCI: init bdf=00:01.0 id=8086:7000
PIIX3/PIIX4 init: elcr=00 0c
PCI: init bdf=00:01.1 id=8086:7010
PCI: init bdf=00:01.2 id=8086:7020
PCI: init bdf=00:01.3 id=8086:7113
Using pmtimer, ioport 0x608
PCI: init bdf=00:02.0 id=8086:5916
Intel IGD OpRegion enabled at 0xbfffe000, size 8KB, dev 00:02.0
Intel IGD BDSM enabled at 0xbf700000, size 8MB, dev 00:02.0
PCI: init bdf=00:03.0 id=1af4:1052
PCI: init bdf=00:04.0 id=1af4:1052
PCI: init bdf=00:05.0 id=1af4:1012
PCI: init bdf=00:06.0 id=8086:293e
PCI: init bdf=00:07.0 id=1b36:0007
PCI: init bdf=00:08.0 id=1af4:1001
PCI: init bdf=00:14.0 id=1af4:1000
PCI: init bdf=00:1f.0 id=8086:9d58
PCI: Using 00:02.0 for primary VGA
init smm
init mtrr
handle_smp: apic_id=0x1
handle_smp: apic_id=0x3
handle_smp: apic_id=0x2
Found 4 cpu(s) max supported 4 cpu(s)
init PIR table
Copying PIR from 0xbffbfcc0 to 0x000f4ea0
init MPTable
Copying MPTABLE from 0x00006e60/bffa4470 to 0x000f4d80
Copying SMBIOS entry point from 0x00006e60 to 0x000f4bd0
load ACPI tables
init timer
WARNING - Timeout at wait_reg8:81!
Scan for VGA option rom
Running option rom at c000:0003
Attaching gdb on qemu only confirmed that we were looping "somewhere" in
the
guest VM BIOS (judging from the address space between 0x6702 and 0x670C).
As a side note, we never managed to get the UPT mode to output on the
displays
(even on the Thinkpad X260, where legacy PT works). Perhaps because we
tried on
a Q35/UEFI platform back then. On the guest, we got rid of the "error 43"
in
Windows after updating to the latest intel driver. Also, it always
indicates
the presence of a second monitor in the configuration dialogs (even without
the
x-igd-opregion=on option which make me doubt the actual screen is even
detected).
On the Lenovo X260, we were luckier with the Q35/Seabios combo: we managed
once to get the external display to work and even then the internal display
had
brightness issues and was unreadable.
We identified some differences between our test hardware:
- HP Probook's processor is a i3-7100U (Kabylake), graphic chip is a Intel
HD Graphics 620 (8086:5916)
- Lenovo X260's processor is a i3-6100U (Skylake), graphic chip is a Intel
HD Graphics 520 GT2 (8086:1916)
On the Linux host, we are using:
- a mix of linux Kernel 4.15.15 (for some early tests) and 4.16 (for all
the debug output in the email)
- Qemu 2.12 or git master (HEAD of master on 4/25/2018)
We believe that Qemu could currently be lacking support for Gen9 KBL_GT2
graphics chips and that some memory regions need to be "reserved/mapped" or
some
"stolen memory" should be declared (we are clearly not expert here, we just
looked at how the previous commits on pci_quirks.c handled newer generation
IGD
hardware in Qemu). We haven't ruled out yet that an interrupt could be
triggered
and we would be enterring an interrupt loop. We are a little at odds on how
to
direct our debug next:
- do you know ways to check for memory write error in Qemu (in case the
device
is trying to communicate with a memory region that have not been mapped)?
- how do we check for interrupt loop?
We are also more than open to other suggestions. :-)
Best regards,
Tony Cheneau
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