Re: [regression, bisected, pci/iommu] Bug 216865 - Black screen when amdgpu started during 6.2-rc1 boot with AMD IOMMU enabled

[Baolu Lu]

On 2023/1/4 2:55, Matt Fagnani wrote:
> I reproduced the problem with 6.2-rc1 in a Fedora 37 installation with early kdump enabled as described athttps://fedoraproject.org/wiki/How_to_use_kdump_to_debug_kernel_crashes  https://github.com/k-hagio/fedora-kexec-tools/blob/master/early-kdump-howto.txt  I panicked the kernel with sysrq+alt+c. The dmesg saved with the kdump showed warnings at drivers/pci/ats.c:251 pci_disable_pri+0x75/0x80 and at drivers/pci/ats.c:419 pci_disable_pasid+0x45/0x50 involving AMD IOMMU and amdgpu functions in the trace. Since those warnings' were
> if (WARN_ON(!pdev->pri_enabled)) and if (WARN_ON(!pdev->pasid_enabled)), pci_disable_pri and pci_disable_pasid looked like they were called when pdev->pri_enabled and pdev->pasid_enabled were both false.
> A null pointer dereference occurred right after that which made amdgpu crash.
>
> [   13.132368] [drm] amdgpu kernel modesetting enabled.
> [   13.133766] amdgpu: Topology: Add APU node [0x0:0x0]
> [   13.137596] Console: switching to colour dummy device 80x25
> [   13.143717] amdgpu 0000:00:01.0: vgaarb: deactivate vga console
> [   13.143970] [drm] initializing kernel modesetting (CARRIZO 0x1002:0x9874 0x103C:0x8332 0xCA).
> [   13.144205] [drm] register mmio base: 0xF0400000
> [   13.144209] [drm] register mmio size: 262144
> [   13.144310] [drm] add ip block number 0 <vi_common>
> [   13.144316] [drm] add ip block number 1 <gmc_v8_0>
> [   13.144320] [drm] add ip block number 2 <cz_ih>
> [   13.144324] [drm] add ip block number 3 <gfx_v8_0>
> [   13.144328] [drm] add ip block number 4 <sdma_v3_0>
> [   13.144332] [drm] add ip block number 5 <powerplay>
> [   13.144336] [drm] add ip block number 6 <dm>
> [   13.144340] [drm] add ip block number 7 <uvd_v6_0>
> [   13.144343] [drm] add ip block number 8 <vce_v3_0>
> [   13.144347] [drm] add ip block number 9 <acp_ip>
> [   13.144388] amdgpu 0000:00:01.0: amdgpu: Fetched VBIOS from VFCT
> [   13.144397] amdgpu: ATOM BIOS: 113-C75100-031
> [   13.144425] [drm] UVD is enabled in physical mode
> [   13.144431] [drm] VCE enabled in physical mode
> [   13.144435] amdgpu 0000:00:01.0: amdgpu: Trusted Memory Zone (TMZ) feature not supported
> [   13.144491] [drm] vm size is 64 GB, 2 levels, block size is 10-bit, fragment size is 9-bit
> [   13.144503] amdgpu 0000:00:01.0: amdgpu: VRAM: 512M 0x000000F400000000 - 0x000000F41FFFFFFF (512M used)
> [   13.144511] amdgpu 0000:00:01.0: amdgpu: GART: 1024M 0x000000FF00000000 - 0x000000FF3FFFFFFF
> [   13.144524] [drm] Detected VRAM RAM=512M, BAR=512M
> [   13.144529] [drm] RAM width 64bits UNKNOWN
> [   13.144623] [drm] amdgpu: 512M of VRAM memory ready
> [   13.144630] [drm] amdgpu: 3572M of GTT memory ready.
> [   13.144653] [drm] GART: num cpu pages 262144, num gpu pages 262144
> [   13.144705] [drm] PCIE GART of 1024M enabled (table at 0x000000F400600000).
> [   13.158820] amdgpu: hwmgr_sw_init smu backed is smu8_smu
> [   13.175036] [drm] Found UVD firmware Version: 1.91 Family ID: 11
> [   13.175097] [drm] UVD ENC is disabled
> [   13.186675] [drm] Found VCE firmware Version: 52.4 Binary ID: 3
> [   13.187879] amdgpu: smu version 27.18.00
> [   13.193760] [drm] DM_PPLIB: values for Engine clock
> [   13.193773] [drm] DM_PPLIB:	 300000
> [   13.193776] [drm] DM_PPLIB:	 480000
> [   13.193779] [drm] DM_PPLIB:	 533340
> [   13.193781] [drm] DM_PPLIB:	 576000
> [   13.193784] [drm] DM_PPLIB:	 626090
> [   13.193786] [drm] DM_PPLIB:	 685720
> [   13.193788] [drm] DM_PPLIB:	 720000
> [   13.193791] [drm] DM_PPLIB:	 757900
> [   13.193793] [drm] DM_PPLIB: Validation clocks:
> [   13.193796] [drm] DM_PPLIB:    engine_max_clock: 75790
> [   13.193799] [drm] DM_PPLIB:    memory_max_clock: 93300
> [   13.193802] [drm] DM_PPLIB:    level           : 8
> [   13.193806] [drm] DM_PPLIB: values for Display clock
> [   13.193809] [drm] DM_PPLIB:	 300000
> [   13.193811] [drm] DM_PPLIB:	 400000
> [   13.193814] [drm] DM_PPLIB:	 496560
> [   13.193816] [drm] DM_PPLIB:	 626090
> [   13.193819] [drm] DM_PPLIB:	 685720
> [   13.193821] [drm] DM_PPLIB:	 757900
> [   13.193823] [drm] DM_PPLIB:	 800000
> [   13.193825] [drm] DM_PPLIB:	 847060
> [   13.193828] [drm] DM_PPLIB: Validation clocks:
> [   13.193830] [drm] DM_PPLIB:    engine_max_clock: 75790
> [   13.193833] [drm] DM_PPLIB:    memory_max_clock: 93300
> [   13.193836] [drm] DM_PPLIB:    level           : 8
> [   13.193839] [drm] DM_PPLIB: values for Memory clock
> [   13.193842] [drm] DM_PPLIB:	 667000
> [   13.193844] [drm] DM_PPLIB:	 933000
> [   13.193847] [drm] DM_PPLIB: Validation clocks:
> [   13.193849] [drm] DM_PPLIB:    engine_max_clock: 75790
> [   13.193852] [drm] DM_PPLIB:    memory_max_clock: 93300
> [   13.193854] [drm] DM_PPLIB:    level           : 8
> [   13.193973] [drm] Display Core initialized with v3.2.215!
> [   13.309967] [drm] UVD initialized successfully.
> [   13.511031] [drm] VCE initialized successfully.
> [   13.515217] kfd kfd: amdgpu: Allocated 3969056 bytes on gart
> [   13.515442] amdgpu: sdma_bitmap: f
> [   13.515549] ------------[ cut here ]------------
> [   13.515555] WARNING: CPU: 0 PID: 477 at drivers/pci/ats.c:251 pci_disable_pri+0x75/0x80
> [   13.515571] Modules linked in: amdgpu(+) drm_ttm_helper ttm iommu_v2 hid_logitech_hidpp crct10dif_pclmul drm_buddy crc32_pclmul gpu_sched crc32c_intel polyval_clmulni polyval_generic ghash_clmulni_intel sha512_ssse3 drm_display_helper wdat_wdt serio_raw hid_multitouch sp5100_tco hid_logitech_dj r8169 cec video wmi scsi_dh_rdac scsi_dh_emc scsi_dh_alua fuse dm_multipath
> [   13.515620] CPU: 0 PID: 477 Comm: systemd-udevd Kdump: loaded Not tainted 6.2.0-0.rc1.14.fc38.x86_64 #1
> [   13.515628] Hardware name: HP HP Laptop 15-bw0xx/8332, BIOS F.52 12/03/2019
> [   13.515634] RIP: 0010:pci_disable_pri+0x75/0x80
> [   13.515642] Code: 54 24 06 89 ee 48 89 df 83 e2 fe 66 89 54 24 06 0f b7 d2 e8 1d e1 fc ff 80 a3 4b 08 00 00 fd 48 83 c4 08 5b 5d e9 2b 8b 69 00 <0f> 0b eb b6 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90
> [   13.515651] RSP: 0018:ffffbaf4407ab8e8 EFLAGS: 00010046
> [   13.515658] RAX: 0000000000000000 RBX: ffff90aa00ac4000 RCX: 0000000000000009
> [   13.515663] RDX: 0000000000000000 RSI: 0000000000000014 RDI: ffff90aa00ac4000
> [   13.515668] RBP: ffff90aa0e0c3810 R08: 0000000000000002 R09: 0000000000000000
> [   13.515673] R10: 0000000000000000 R11: ffffffffade4e430 R12: ffff90aa011a8800
> [   13.515678] R13: ffff90aa0e0c3800 R14: ffff90aa011a8800 R15: ffff90aa0e0c3960
> [   13.515683] FS:  00007fabd67feb40(0000) GS:ffff90aaf7400000(0000) knlGS:0000000000000000
> [   13.515689] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   13.515695] CR2: 00007f5689ff54c0 CR3: 0000000100f16000 CR4: 00000000001506f0
> [   13.515700] Call Trace:
> [   13.515704]  <TASK>
> [   13.515710]  amd_iommu_attach_device+0x2e0/0x300
> [   13.515719]  __iommu_attach_device+0x1b/0x90
> [   13.515727]  iommu_attach_group+0x65/0xa0
> [   13.515735]  amd_iommu_init_device+0x16b/0x250 [iommu_v2]
> [   13.515747]  kfd_iommu_resume+0x4c/0x1a0 [amdgpu]
> [   13.517094]  kgd2kfd_resume_iommu+0x12/0x30 [amdgpu]
> [   13.518419]  kgd2kfd_device_init.cold+0x346/0x49a [amdgpu]
> [   13.519699]  amdgpu_amdkfd_device_init+0x142/0x1d0 [amdgpu]
> [   13.520877]  amdgpu_device_init.cold+0x19f5/0x1e21 [amdgpu]
> [   13.522118]  ? _raw_spin_lock_irqsave+0x23/0x50
> [   13.522126]  amdgpu_driver_load_kms+0x15/0x110 [amdgpu]
> [   13.523386]  amdgpu_pci_probe+0x161/0x370 [amdgpu]
> [   13.524516]  local_pci_probe+0x41/0x80
> [   13.524525]  pci_device_probe+0xb3/0x220
> [   13.524533]  really_probe+0xde/0x380
> [   13.524540]  ? pm_runtime_barrier+0x50/0x90
> [   13.524546]  __driver_probe_device+0x78/0x170
> [   13.524555]  driver_probe_device+0x1f/0x90
> [   13.524560]  __driver_attach+0xce/0x1c0
> [   13.524565]  ? __pfx___driver_attach+0x10/0x10
> [   13.524570]  bus_for_each_dev+0x73/0xa0
> [   13.524575]  bus_add_driver+0x1ae/0x200
> [   13.524580]  driver_register+0x89/0xe0
> [   13.524586]  ? __pfx_init_module+0x10/0x10 [amdgpu]
> [   13.525819]  do_one_initcall+0x59/0x230
> [   13.525828]  do_init_module+0x4a/0x200
> [   13.525834]  __do_sys_init_module+0x157/0x180
> [   13.525839]  do_syscall_64+0x5b/0x80
> [   13.525845]  ? handle_mm_fault+0xff/0x2f0
> [   13.525850]  ? do_user_addr_fault+0x1ef/0x690
> [   13.525856]  ? exc_page_fault+0x70/0x170
> [   13.525860]  entry_SYSCALL_64_after_hwframe+0x72/0xdc
> [   13.525867] RIP: 0033:0x7fabd66cde4e
> [   13.525872] Code: 48 8b 0d e5 5f 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 af 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d b2 5f 0c 00 f7 d8 64 89 01 48
> [   13.525878] RSP: 002b:00007ffdd89bc6a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000af
> [   13.525884] RAX: ffffffffffffffda RBX: 0000563e4d23f0a0 RCX: 00007fabd66cde4e
> [   13.525887] RDX: 00007fabd6817453 RSI: 000000000174fb66 RDI: 00007fabd3bd4010
> [   13.525890] RBP: 00007fabd6817453 R08: 0000563e4d237c70 R09: 00007fabd672f900
> [   13.525893] R10: 0000000000000005 R11: 0000000000000246 R12: 0000000000020000
> [   13.525896] R13: 0000563e4d239060 R14: 0000000000000000 R15: 0000563e4d23e450
> [   13.525900]  </TASK>
> [   13.525902] ---[ end trace 0000000000000000 ]---
> [   13.525964] ------------[ cut here ]------------

This (including the following) kernel traces are triggered by the
following code.

1698 static int pdev_pri_ats_enable(struct pci_dev *pdev)
1699 {
1700         int ret;
1701
1702         /* Only allow access to user-accessible pages */
1703         ret = pci_enable_pasid(pdev, 0);
1704         if (ret)
1705                 goto out_err;

[--cut for short--]

1724 out_err:
1725         pci_disable_pri(pdev);
1726         pci_disable_pasid(pdev);
1727
1728         return ret;
1729 }

pci_disable_pri() and pci_disable_pasid() are called with PCI PASID and
PRI not enabled. There are WARN_ON()s in the pci code for such cases.

This happens in the domain attach device path. I haven't figured out why
the failure of PASID or PRI enabling will cause the domain attach device
to fail. And also why pci_pasid_features() and pci_pri_supported() are
not called before pci_enable_pasid/pri().

commit 201007ef707a ("PCI: Enable PASID only when ACS RR & UF enabled on
upstream path") requires ACS P2P Request Redirect and Upstream
Forwarding are enabled for the path leading to the device when enabling
PASID because PCIe fabric routes Memory Requests based on the TLP
address, ignoring any PASID. I guess this is the reason why
pci_enable_pasid() returns failure and discovers above buggy code.

--
Best regards,
baolu