Re: B580 on POWER9: Unable to handle kernel data access on read at 0xc00a0000000003cc

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Mon, Mar 10, 2025 at 01:04:36AM +0900, Simon Richter wrote:
> Hi,
> 
> I've built a horrible contraption and received the following output:
> 
> BUG: Unable to handle kernel data access on read at 0xc00a0000000003cc
> Faulting instruction address: 0xc00800000dd46484
> Oops: Kernel access of bad area, sig: 11 [#1]
> LE PAGE_SIZE=4K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV
> Modules linked in: xe(+) xt_conntrack nft_chain_nat xt_MASQUERADE nf_nat
> nf_conntrack_netlink nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xfrm_user
> xfrm_algo xt_addrtype nft_compat x_tables nf_tables libcrc32c nfnetlink
> br_netfilter bridge stp llc overlay binfmt_misc evdev joydev hid_generic
> usbhid hid cec rc_core drm_gpuvm drm_exec drm_buddy gpu_sched
> drm_suballoc_helper drm_display_helper ast drm_ttm_helper ttm snd_hda_intel
> drm_shmem_helper snd_intel_dspcfg drm_kms_helper snd_hda_codec snd_hda_core
> drm ofpart snd_hwdep snd_pcm xts ipmi_powernv snd_timer ipmi_devintf
> powernv_flash snd vmx_crypto gf128mul mtd ipmi_msghandler opal_prd soundcore
> at24 drm_panel_orientation_quirks i2c_algo_bit regmap_i2c ext4 crc16 mbcache
> jbd2 crc32c_generic dm_mod xhci_pci xhci_hcd tg3 nvme crc32c_vpmsum usbcore
> nvme_core libphy usb_common nvme_auth [last unloaded: xe]
> CPU: 32 UID: 0 PID: 453 Comm: kworker/32:1 Not tainted
> 6.12.12+bpo-powerpc64le #1  Debian 6.12.12-1~bpo12+1
> Hardware name: T2P9D01 REV 1.01 POWER9 0x4e1202 opal:skiboot-9858186 PowerNV
> Workqueue: events work_for_cpu_fn
> NIP:  c00800000dd46484 LR: c00800000dd46384 CTR: 000000003006c394
> REGS: c00020000a637660 TRAP: 0300   Not tainted (6.12.12+bpo-powerpc64le
> Debian 6.12.12-1~bpo12+1)
> MSR:  9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE>  CR: 24008488  XER:
> 20040000
> CFAR: c00800000dd46398 DAR: c00a0000000003cc DSISR: 40000000 IRQMASK: 0
> GPR00: c00800000dd46384 c00020000a637900 c00800000db30600 c00a0000000003cc
> GPR04: 0000000000000000 0000000000000004 0000000035c20060 0000000035c20060
> GPR08: 0000000000000000 c00a000000000000 0000000000000000 0000000000008000
> GPR12: 0000000000000000 c0002007ff7ffb00 c00000000017d1cc c000200005d5c200
> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> GPR20: 0000000000000000 c0002007fbeeb280 c00800000df35350 c00800000df35700
> GPR24: c00800000df35730 c000200006f60000 0000000000000001 c000200006f61628
> GPR28: 0000000000000001 c0000000027703e0 0000000000000000 c00000000c167000
> NIP [c00800000dd46484] intel_vga_reset_io_mem+0x140/0x188 [xe]
> LR [c00800000dd46384] intel_vga_reset_io_mem+0x40/0x188 [xe]
> Call Trace:
> [c00020000a637900] [c00800000dd46384] intel_vga_reset_io_mem+0x40/0x188 [xe]
> (unreliable)
> [c00020000a637940] [c00800000dcbbd88] hsw_power_well_enable+0x1f0/0x238 [xe]
> [c00020000a637990] [c00800000dcbe470] intel_power_well_enable+0x8c/0xb8 [xe]
> [c00020000a637a00] [c00800000dcb6d08]
> __intel_display_power_get_domain.part.0+0x98/0xf4 [xe]
> [c00020000a637a50] [c00800000dcb9260] intel_power_domains_init_hw+0x94/0x3a8
> [xe]
> [c00020000a637af0] [c00800000dcafca4]
> intel_display_driver_probe_noirq+0xf4/0x300 [xe]
> [c00020000a637b70] [c00800000dc4f124] xe_display_init_noirq+0x80/0x124 [xe]
> [c00020000a637ba0] [c00800000dbcee98] xe_device_probe+0x414/0x768 [xe]
> [c00020000a637c30] [c00800000dc13370] xe_pci_probe+0x77c/0xc60 [xe]
> [c00020000a637d90] [c0000000009f4540] local_pci_probe+0x68/0xf4
> [c00020000a637e10] [c000000000169cdc] work_for_cpu_fn+0x38/0x54
> [c00020000a637e40] [c00000000016ff24] process_one_work+0x1fc/0x4d4
> [c00020000a637ef0] [c000000000170e3c] worker_thread+0x33c/0x504
> [c00020000a637f90] [c00000000017d2fc] kthread+0x138/0x140
> [c00020000a637fe0] [c00000000000de58] start_kernel_thread+0x14/0x18
> Code: ebc1fff0 ebe1fff8 7c0803a6 4e800020 60000000 60000000 60420000
> 3d220000 e9291800 e9290000 386903cc 7c0004ac <8bc903cc> 0c1e0000 4c00012c
> 57c9063e
> ---[ end trace 0000000000000000 ]---
> 
> note: kworker/32:1[453] exited with irqs disabled
> 
> The faulting line is
> 
>     outb(inb(VGA_MIS_R), VGA_MIS_W);
> 
> in drivers/gpu/drm/i915/display/intel_vga.c
> 
> The 0x3cc offset is VGA_MIS_R, and R9 points to c00a000000000000, where the
> I/O ports are mapped -- however the legacy ports don't seem to be active if
> the card was never initialized at boot, which it isn't, because the BMC's
> VGA emulation is preferred.
> 
> Commenting out the call to intel_vga_reset_io_mem solves the problem, and I
> get wonderful 1080p60 output -- but obviously that is not a generic
> solution.

Hi Simon, thanks for reporting this. Could you please report this to our gitlab
issues so we ensure this doesn't get lost on this busy mailing list?

https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.html

Since you are building your own kernel. Would you mind trying to reproduce
with latest drm-tip branch from https://gitlab.freedesktop.org/drm/tip

I believe Maarten had done some changes on this area lately.
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

in case he has some quick thoughts...

Thanks,
Rodrigo.

> 
>    Simon