alvisc / qemu Goto Github PK

/*
; * Copyright 2015  Alexander V. Schlegel
; *
; *
; *
; *
; * License: GPL Version 2.0
; */

TOC
1. Description
2. Test System
3. How to test
4. What to change for nvidia and intel
5. Current Status
6. Tips


1. Description

This is an attemp to create a gpu passthrough without legacy vga accesses to graphics card.

Legacy accesses to vga registers are replaced through MMIO accesses(BAR2).
E.g. 0x3cc to MMIOBASE+0x3cc

Legacy accesses to 0xA0000 region are replaced through accesses to plain framebuffer(BAR0).

Memory Map in textmode 03h:

A0000 Region:

0000: c0 a0 c1 a1 c2 a2 c3 a3 planes 0 and 1
0000: f0 f1	              plane 2 (font, hidden)

Framebuffer:

0000: c0 a0 f0 xx xx xx f1 xx c1 a1

c0 - cx: character bytes
a0 - ax: attribute bytes (colors)
f0 - fx: font bytes

QEMU 2.1.3 monitor - type 'help' for more information
(qemu) x /32b 0xb8000
00000000000b8000: 0x53 0x07 0x65 0x07 0x61 0x07 0x42 0x07
00000000000b8008: 0x49 0x07 0x4f 0x07 0x53 0x07 0x20 0x07
00000000000b8010: 0x28 0x07 0x76 0x07 0x65 0x07 0x72 0x07
00000000000b8018: 0x73 0x07 0x69 0x07 0x6f 0x07 0x6e 0x07
(qemu) x /32b 0xe0000000
00000000e0000000: 0x53 0x07 0x00 0xff 0x75 0x38 0x00 0xff
00000000e0000008: 0x65 0x07 0x00 0xff 0x75 0x38 0x00 0xff
00000000e0000010: 0x61 0x07 0x00 0xff 0x75 0x38 0x00 0xff
00000000e0000018: 0x42 0x07 0x00 0xff 0x75 0x38 0x00 0xff


2. Test System

My Configuration:

i7-3820
Asrock X79 Extreme6
Radeon 6950, 2:00.0, boot card, primary card, passthrough card
Radeon 5450, 1:00.0, card for linux desktop

cat /proc/cmdline 
BOOT_IMAGE=/boot/kernel-3.19 root=/dev/sda1 raid=noautodetect pci-stub.ids=1002:6719,1002:aa80 fbcon=map:1 intel_iommu=on vga=0

No initrd, pcistub in kernel


3. How to test

Testing DOS:

x86_64-softmmu/qemu-system-x86_64 -spice port=5900,disable-ticketing,seamless-migration=on  \
-netdev tap,id=hostnet0 -device virtio-net,netdev=hostnet0,id=net0,mac=xx:xx:xx:xx:xx:xx \
-chardev pipe,path=/tmp/qemudebugpipe,id=seabios \
-device isa-debugcon,iobase=0x402,chardev=seabios  \
-cpu host,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time \
-enable-kvm   -nodefaults -no-user-config  \
-nographic   -monitor  telnet::4444,server,nowait  \
-vga none -device pci-assign,host=02:00.0  \
/home/ax/vm/dosplatte.img 


Testing Windows:

 x86_64-softmmu/qemu-system-x86_64 -name windows  -M pc-i440fx-1.4 -cpu qemu32 -enable-kvm \
 -m 2048 -smp 2,sockets=2,cores=1,threads=1  -no-user-config -nodefaults   \
 -monitor telnet::4444,server,nowait  -rtc base=localtime -no-shutdown  \
 -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2  \
 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5  \
 -drive file=vmWindows.img,if=none,id=drive-ide0-0-0,format=raw,cache=none  \
 -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1  \
 -drive if=none,id=drive-ide0-1-0,readonly=on,format=raw  \
 -device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0  \
 -drive file=develop.img,if=none,id=drive-virtio-disk0,format=raw,cache=none \
 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk0,id=virtio-disk0  \
 -drive file=vs2010.img,if=none,id=drive-virtio-disk1,format=raw,cache=none  \
 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x9,drive=drive-virtio-disk1,id=virtio-disk1  \
 -netdev tap,id=hostnet0 \
 -device e1000,netdev=hostnet0,id=net0,mac=xx:xx:xx:xx:xx:xx,bus=pci.0,addr=0x3  \
 -chardev pty,id=charserial0 \
 -device isa-serial,chardev=charserial0,id=serial0 \
 -chardev socket,id=charserial1,host=127.0.0.1,port=4555,server,nowait  \
 -device isa-serial,chardev=charserial1,id=serial1 \
 -chardev spicevmc,id=charchannel0,name=vdagent  \
 -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0  \
 -spice port=5900,disable-ticketing,seamless-migration=on  \
 -vga none -device pci-assign,host=02:00.0 \
 -device pci-assign,host=00:1a.0,addr=1a.0,id=usb0  

(qemu) info pci
  Bus  0, device   0, function 0:
    Host bridge: PCI device 8086:1237
      id ""
  Bus  0, device   1, function 0:
    ISA bridge: PCI device 8086:7000
      id ""
  Bus  0, device   1, function 1:
    IDE controller: PCI device 8086:7010
      BAR4: I/O at 0xc120 [0xc12f].
      id ""
  Bus  0, device   1, function 3:
    Bridge: PCI device 8086:7113
      IRQ 9.
      id ""
  Bus  0, device   2, function 0:
    Ethernet controller: PCI device 1af4:1000
      IRQ 10.
      BAR0: I/O at 0xc100 [0xc11f].
      BAR1: 32 bit memory at 0xfebc0000 [0xfebc0fff].
      BAR6: 32 bit memory at 0xffffffffffffffff [0x0003fffe].
      id "net0"
  Bus  0, device   3, function 0:
    VGA controller: PCI device 1002:6719
      IRQ 11.
      BAR0: 64 bit prefetchable memory at 0xe0000000 [0xefffffff].
      BAR2: 64 bit memory at 0xfeb80000 [0xfeb9ffff].
      BAR4: I/O at 0xc000 [0xc0ff].
      BAR6: 32 bit memory at 0xffffffffffffffff [0x0001fffe].
      id ""


4. What to change for nvidia and intel

Code is written for radeon cards.
0x3c3 quirk is hardcoded for radeon in pci-assign

MMIO region is hardcoded to BAR2, must be changed for nvidia or intel.
Framebuffer region is hardcoded to BAR0, must be changed for nvidia or intel.


5. Current Status

Standard DOS mode (text mode 03h) works
Standard VGA mode (graphics mode 12h) works partially 

Windows Xp starts without boot logo
Windows 7 starts without boot logo, black screen until radeon driver loads


6. Tips

Switch to S3(suspend to ram) to deinit graphics card before restart the virtual machine.