[Qemu-devel] [Bug 1809684] [NEW] amdgpu passthrough on POWER9 (ppc64el) not working

[Timothy Pearson]

Public bug reported:

When attempting to pass a Vega 56 GPU to a virtualized guest using QEMU
3.1 on ppc64el (POWER9), the guest is unable to initialize the GPU.
Further digging reveals the driver attempting to allocate a large BAR,
which then fails:

[    6.058544] [drm] PCI I/O BAR is not found.
<snip uninteresting bits>
[    6.679193] amdgpu 0000:00:03.0: BAR 2: releasing [mem 
0x210400000000-0x2104001fffff pref]
[    6.679306] amdgpu 0000:00:03.0: BAR 0: releasing [mem 
0x210200000000-0x2103ffffffff pref]
[    6.679361] amdgpu 0000:00:03.0: BAR 0: no space for [mem size 0x200000000 
pref]
[    6.679403] amdgpu 0000:00:03.0: BAR 0: failed to assign [mem size 
0x200000000 pref]
[    6.679444] amdgpu 0000:00:03.0: BAR 2: assigned [mem 
0x200080200000-0x2000803fffff pref]
[    6.681420] amdgpu 0000:00:03.0: VRAM: 8176M 0x000000F400000000 - 
0x000000F5FEFFFFFF (8176M used)
[    6.681507] amdgpu 0000:00:03.0: GART: 512M 0x0000000000000000 - 
0x000000001FFFFFFF
[    6.681594] amdgpu 0000:00:03.0: AGP: 267419648M 0x000000F800000000 - 
0x0000FFFFFFFFFFFF
[    6.681653] [drm] Detected VRAM RAM=8176M, BAR=0M
[    6.681688] [drm] RAM width 2048bits HBM
[    6.681885] [TTM] Zone  kernel: Available graphics memory: 4176288 kiB
[    6.681978] [TTM] Zone   dma32: Available graphics memory: 2097152 kiB
[    6.682043] [TTM] Initializing pool allocator
[    6.682159] [drm] amdgpu: 8176M of VRAM memory ready
[    6.682249] [drm] amdgpu: 6117M of GTT memory ready.
[    6.682387] [drm] GART: num cpu pages 8192, num gpu pages 131072
[    6.682466] amdgpu 0000:00:03.0: (-22) kernel bo map failed
[    6.682539] [drm:amdgpu_device_init [amdgpu]] *ERROR* 
amdgpu_vram_scratch_init failed -22
[    6.682592] amdgpu 0000:00:03.0: amdgpu_device_ip_init failed
[    6.682636] amdgpu 0000:00:03.0: Fatal error during GPU init

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1809684

Title:
  amdgpu passthrough on POWER9 (ppc64el) not working

Status in QEMU:
  New

Bug description:
  When attempting to pass a Vega 56 GPU to a virtualized guest using
  QEMU 3.1 on ppc64el (POWER9), the guest is unable to initialize the
  GPU.  Further digging reveals the driver attempting to allocate a
  large BAR, which then fails:

  [    6.058544] [drm] PCI I/O BAR is not found.
  <snip uninteresting bits>
  [    6.679193] amdgpu 0000:00:03.0: BAR 2: releasing [mem 
0x210400000000-0x2104001fffff pref]
  [    6.679306] amdgpu 0000:00:03.0: BAR 0: releasing [mem 
0x210200000000-0x2103ffffffff pref]
  [    6.679361] amdgpu 0000:00:03.0: BAR 0: no space for [mem size 0x200000000 
pref]
  [    6.679403] amdgpu 0000:00:03.0: BAR 0: failed to assign [mem size 
0x200000000 pref]
  [    6.679444] amdgpu 0000:00:03.0: BAR 2: assigned [mem 
0x200080200000-0x2000803fffff pref]
  [    6.681420] amdgpu 0000:00:03.0: VRAM: 8176M 0x000000F400000000 - 
0x000000F5FEFFFFFF (8176M used)
  [    6.681507] amdgpu 0000:00:03.0: GART: 512M 0x0000000000000000 - 
0x000000001FFFFFFF
  [    6.681594] amdgpu 0000:00:03.0: AGP: 267419648M 0x000000F800000000 - 
0x0000FFFFFFFFFFFF
  [    6.681653] [drm] Detected VRAM RAM=8176M, BAR=0M
  [    6.681688] [drm] RAM width 2048bits HBM
  [    6.681885] [TTM] Zone  kernel: Available graphics memory: 4176288 kiB
  [    6.681978] [TTM] Zone   dma32: Available graphics memory: 2097152 kiB
  [    6.682043] [TTM] Initializing pool allocator
  [    6.682159] [drm] amdgpu: 8176M of VRAM memory ready
  [    6.682249] [drm] amdgpu: 6117M of GTT memory ready.
  [    6.682387] [drm] GART: num cpu pages 8192, num gpu pages 131072
  [    6.682466] amdgpu 0000:00:03.0: (-22) kernel bo map failed
  [    6.682539] [drm:amdgpu_device_init [amdgpu]] *ERROR* 
amdgpu_vram_scratch_init failed -22
  [    6.682592] amdgpu 0000:00:03.0: amdgpu_device_ip_init failed
  [    6.682636] amdgpu 0000:00:03.0: Fatal error during GPU init

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