Re: [PATCH v3 3/5] drm/xe/regs: fix RING_CTL_SIZE(size) calculation

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

On Wed, Jul 23, 2025 at 04:45:15PM +0900, Simon Richter wrote:
> From: Mingcong Bai <jeffbai@aosc.io>
> 
> Similar to the preceding patch for GuC (and with the same references),
> Intel GPUs expects command buffers to align to 4KiB boundaries.
> 
> Current code uses `PAGE_SIZE' as an assumed alignment reference but 4KiB
> kernel page sizes is by no means a guarantee. On 16KiB-paged kernels, this
> causes driver failures during boot up:
> 
> [   14.018975] ------------[ cut here ]------------
> [   14.023562] xe 0000:09:00.0: [drm] GT0: Kernel-submitted job timed out
> [   14.030084] WARNING: CPU: 3 PID: 564 at drivers/gpu/drm/xe/xe_guc_submit.c:1181 guc_exec_queue_timedout_job+0x1c0/0xacc [xe]
> [   14.041300] Modules linked in: nf_conntrack_netbios_ns(E) nf_conntrack_broadcast(E) nft_fib_inet(E) nft_fib_ipv4(E) nft_fib_ipv6(E) nft_fib(E) nft_reject_inet(E) nf_reject_ipv4(E) nf_reject_ipv6(E) nft_reject(E) nft_ct(E) nft_chain_nat(E) ip6table_nat(E) ip6table_mangle(E) ip6table_raw(E) ip6table_security(E) iptable_nat(E) nf_nat(E) nf_conntrack(E) nf_defrag_ipv6(E) nf_defrag_ipv4(E) rfkill(E) iptable_mangle(E) iptable_raw(E) iptable_security(E) ip_set(E) nf_tables(E) ip6table_filter(E) ip6_tables(E) iptable_filter(E) snd_hda_codec_conexant(E) snd_hda_codec_generic(E) snd_hda_codec_hdmi(E) nls_iso8859_1(E) snd_hda_intel(E) snd_intel_dspcfg(E) qrtr(E) nls_cp437(E) snd_hda_codec(E) spi_loongson_pci(E) rtc_efi(E) snd_hda_core(E) loongson3_cpufreq(E) spi_loongson_core(E) snd_hwdep(E) snd_pcm(E) snd_timer(E) snd(E) soundcore(E) gpio_loongson_64bit(E) input_leds(E) rtc_loongson(E) i2c_ls2x(E) mousedev(E) sch_fq_codel(E) fuse(E) nfnetlink(E) dmi_sysfs(E) ip_tables(E) x_tables(E) xe(E) d
>  rm_gpuvm(E) drm_buddy(E) gpu_sched(E)
> [   14.041369]  drm_exec(E) drm_suballoc_helper(E) drm_display_helper(E) cec(E) rc_core(E) hid_generic(E) tpm_tis_spi(E) r8169(E) realtek(E) led_class(E) loongson(E) i2c_algo_bit(E) drm_ttm_helper(E) ttm(E) drm_client_lib(E) drm_kms_helper(E) sunrpc(E) i2c_dev(E)
> [   14.153910] CPU: 3 UID: 0 PID: 564 Comm: kworker/u32:2 Tainted: G            E      6.14.0-rc4-aosc-main-gbad70b1cd8b0-dirty #7
> [   14.165325] Tainted: [E]=UNSIGNED_MODULE
> [   14.169220] Hardware name: Loongson Loongson-3A6000-HV-7A2000-1w-V0.1-EVB/Loongson-3A6000-HV-7A2000-1w-EVB-V1.21, BIOS Loongson-UDK2018-V4.0.05756-prestab
> [   14.182970] Workqueue: gt-ordered-wq drm_sched_job_timedout [gpu_sched]
> [   14.189549] pc ffff8000024f3760 ra ffff8000024f3760 tp 900000012f150000 sp 900000012f153ca0
> [   14.197853] a0 0000000000000000 a1 0000000000000000 a2 0000000000000000 a3 0000000000000000
> [   14.206156] a4 0000000000000000 a5 0000000000000000 a6 0000000000000000 a7 0000000000000000
> [   14.214458] t0 0000000000000000 t1 0000000000000000 t2 0000000000000000 t3 0000000000000000
> [   14.222761] t4 0000000000000000 t5 0000000000000000 t6 0000000000000000 t7 0000000000000000
> [   14.231064] t8 0000000000000000 u0 900000000195c0c8 s9 900000012e4dcf48 s0 90000001285f3640
> [   14.239368] s1 90000001004f8000 s2 ffff8000026ec000 s3 0000000000000000 s4 900000012e4dc028
> [   14.247672] s5 90000001009f5e00 s6 000000000000137e s7 0000000000000001 s8 900000012f153ce8
> [   14.255975]    ra: ffff8000024f3760 guc_exec_queue_timedout_job+0x1c0/0xacc [xe]
> [   14.263379]   ERA: ffff8000024f3760 guc_exec_queue_timedout_job+0x1c0/0xacc [xe]
> [   14.270777]  CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)
> [   14.276927]  PRMD: 00000004 (PPLV0 +PIE -PWE)
> [   14.281258]  EUEN: 00000000 (-FPE -SXE -ASXE -BTE)
> [   14.286024]  ECFG: 00071c1d (LIE=0,2-4,10-12 VS=7)
> [   14.290790] ESTAT: 000c0000 [BRK] (IS= ECode=12 EsubCode=0)
> [   14.296329]  PRID: 0014d000 (Loongson-64bit, Loongson-3A6000-HV)
> [   14.302299] CPU: 3 UID: 0 PID: 564 Comm: kworker/u32:2 Tainted: G            E      6.14.0-rc4-aosc-main-gbad70b1cd8b0-dirty #7
> [   14.302302] Tainted: [E]=UNSIGNED_MODULE
> [   14.302302] Hardware name: Loongson Loongson-3A6000-HV-7A2000-1w-V0.1-EVB/Loongson-3A6000-HV-7A2000-1w-EVB-V1.21, BIOS Loongson-UDK2018-V4.0.05756-prestab
> [   14.302304] Workqueue: gt-ordered-wq drm_sched_job_timedout [gpu_sched]
> [   14.302307] Stack : 900000012f153928 d84a6232d48f1ac7 900000000023eb34 900000012f150000
> [   14.302310]         900000012f153900 0000000000000000 900000012f153908 9000000001c31c70
> [   14.302313]         0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [   14.302315]         0000000000000000 d84a6232d48f1ac7 0000000000000000 0000000000000000
> [   14.302318]         0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [   14.302320]         0000000000000000 0000000000000000 00000000072b4000 900000012e4dcf48
> [   14.302323]         9000000001eb8000 0000000000000000 9000000001c31c70 0000000000000004
> [   14.302325]         0000000000000004 0000000000000000 000000000000137e 0000000000000001
> [   14.302328]         900000012f153ce8 9000000001c31c70 9000000000244174 0000555581840b98
> [   14.302331]         00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d
> [   14.302333]         ...
> [   14.302335] Call Trace:
> [   14.302336] [<9000000000244174>] show_stack+0x3c/0x16c
> [   14.302341] [<900000000023eb30>] dump_stack_lvl+0x84/0xe0
> [   14.302346] [<9000000000288208>] __warn+0x8c/0x174
> [   14.302350] [<90000000017c1918>] report_bug+0x1c0/0x22c
> [   14.302354] [<90000000017f66e8>] do_bp+0x280/0x344
> [   14.302359]
> [   14.302360] ---[ end trace 0000000000000000 ]---
> 
> Revise calculation of `RING_CTL_SIZE(size)' to use `SZ_4K' to fix the
> aforementioned issue.
> 
> Cc: stable@vger.kernel.org
> Fixes: b79e8fd954c4 ("drm/xe: Remove dependency on intel_engine_regs.h")
> Tested-by: Mingcong Bai <jeffbai@aosc.io>
> Tested-by: Wenbin Fang <fangwenbin@vip.qq.com>
> Tested-by: Haien Liang <27873200@qq.com>
> Tested-by: Jianfeng Liu <liujianfeng1994@gmail.com>
> Tested-by: Shirong Liu <lsr1024@qq.com>
> Tested-by: Haofeng Wu <s2600cw2@126.com>
> Link: https://github.com/FanFansfan/loongson-linux/commit/22c55ab3931c32410a077b3ddb6dca3f28223360
> Link: https://t.me/c/1109254909/768552
> Co-developed-by: Shang Yatsen <429839446@qq.com>
> Signed-off-by: Shang Yatsen <429839446@qq.com>
> Signed-off-by: Mingcong Bai <jeffbai@aosc.io>
> ---
>  drivers/gpu/drm/xe/regs/xe_engine_regs.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/regs/xe_engine_regs.h b/drivers/gpu/drm/xe/regs/xe_engine_regs.h
> index 7ade41e2b7b3..a7608c50c907 100644
> --- a/drivers/gpu/drm/xe/regs/xe_engine_regs.h
> +++ b/drivers/gpu/drm/xe/regs/xe_engine_regs.h
> @@ -56,7 +56,7 @@
>  #define RING_START(base)			XE_REG((base) + 0x38)
>  
>  #define RING_CTL(base)				XE_REG((base) + 0x3c)
> -#define   RING_CTL_SIZE(size)			((size) - PAGE_SIZE) /* in bytes -> pages */
> +#define   RING_CTL_SIZE(size)			((size) - SZ_4K) /* in bytes -> pages */

XE_PAGE_SIZE ?

or perhaps we should kill the xe_page_size in favor of only using
SZ_4K directly?

But also, this makes me think about the previous patch. There we should go
then with XE_PAGE_SIZE or with directly SZ_4K instead of creating yet another
define exclusively for GuC.

What I'm trying to say is that we need some consistency...

>  
>  #define RING_START_UDW(base)			XE_REG((base) + 0x48)
>  
> -- 
> 2.47.2
>