[PATCH] drm/amd/display: Fix by adding FPU protection for dcn30_internal_validate_bw

[CHANDAN VURDIGERE NATARAJ]

[WHY]
Below general protection fault observed when WebGL Aquarium is run for
longer duration. If drm debug logs are enabled and set to 0x1f then the
issue is observed within 10 minutes of run.

[  100.717056] general protection fault, probably for non-canonical address 0x2d33302d32323032: 0000 [#1] PREEMPT SMP NOPTI
[  100.727921] CPU: 3 PID: 1906 Comm: DrmThread Tainted: G        W         5.15.30 #12 d726c6a2d6ebe5cf9223931cbca6892f916fe18b
[  100.754419] RIP: 0010:CalculateSwathWidth+0x1f7/0x44f
[  100.767109] Code: 00 00 00 f2 42 0f 11 04 f0 48 8b 85 88 00 00 00 f2 42 0f 10 04 f0 48 8b 85 98 00 00 00 f2 42 0f 11 04 f0 48 8b 45 10 0f 57 c0 <f3> 42 0f 2a 04 b0 0f 57 c9 f3 43 0f 2a 0c b4 e8 8c e2 f3 ff 48 8b
[  100.781269] RSP: 0018:ffffa9230079eeb0 EFLAGS: 00010246
[  100.812528] RAX: 2d33302d32323032 RBX: 0000000000000500 RCX: 0000000000000000
[  100.819656] RDX: 0000000000000001 RSI: ffff99deb712c49c RDI: 0000000000000000
[  100.826781] RBP: ffffa9230079ef50 R08: ffff99deb712460c R09: ffff99deb712462c
[  100.833907] R10: ffff99deb7124940 R11: ffff99deb7124d70 R12: ffff99deb712ae44
[  100.841033] R13: 0000000000000001 R14: 0000000000000000 R15: ffffa9230079f0a0
[  100.848159] FS:  00007af121212640(0000) GS:ffff99deba780000(0000) knlGS:0000000000000000
[  100.856240] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  100.861980] CR2: 0000209000fe1000 CR3: 000000011b18c000 CR4: 0000000000350ee0
[  100.869106] Call Trace:
[  100.871555]  <TASK>
[  100.873655]  ? asm_sysvec_reschedule_ipi+0x12/0x20
[  100.878449]  CalculateSwathAndDETConfiguration+0x1a3/0x6dd
[  100.883937]  dml31_ModeSupportAndSystemConfigurationFull+0x2ce4/0x76da
[  100.890467]  ? kallsyms_lookup_buildid+0xc8/0x163
[  100.895173]  ? kallsyms_lookup_buildid+0xc8/0x163
[  100.899874]  ? __sprint_symbol+0x80/0x135
[  100.903883]  ? dm_update_plane_state+0x3f9/0x4d2
[  100.908500]  ? symbol_string+0xb7/0xde
[  100.912250]  ? number+0x145/0x29b
[  100.915566]  ? vsnprintf+0x341/0x5ff
[  100.919141]  ? desc_read_finalized_seq+0x39/0x87
[  100.923755]  ? update_load_avg+0x1b9/0x607
[  100.927849]  ? compute_mst_dsc_configs_for_state+0x7d/0xd5b
[  100.933416]  ? fetch_pipe_params+0xa4d/0xd0c
[  100.937686]  ? dc_fpu_end+0x3d/0xa8
[  100.941175]  dml_get_voltage_level+0x16b/0x180
[  100.945619]  dcn30_internal_validate_bw+0x10e/0x89b
[  100.950495]  ? dcn31_validate_bandwidth+0x68/0x1fc
[  100.955285]  ? resource_build_scaling_params+0x98b/0xb8c
[  100.960595]  ? dcn31_validate_bandwidth+0x68/0x1fc
[  100.965384]  dcn31_validate_bandwidth+0x9a/0x1fc
[  100.970001]  dc_validate_global_state+0x238/0x295
[  100.974703]  amdgpu_dm_atomic_check+0x9c1/0xbce
[  100.979235]  ? _printk+0x59/0x73
[  100.982467]  drm_atomic_check_only+0x403/0x78b
[  100.986912]  drm_mode_atomic_ioctl+0x49b/0x546
[  100.991358]  ? drm_ioctl+0x1c1/0x3b3
[  100.994936]  ? drm_atomic_set_property+0x92a/0x92a
[  100.999725]  drm_ioctl_kernel+0xdc/0x149
[  101.003648]  drm_ioctl+0x27f/0x3b3
[  101.007051]  ? drm_atomic_set_property+0x92a/0x92a
[  101.011842]  amdgpu_drm_ioctl+0x49/0x7d
[  101.015679]  __se_sys_ioctl+0x7c/0xb8
[  101.015685]  do_syscall_64+0x5f/0xb8
[  101.015690]  ? __irq_exit_rcu+0x34/0x96

[HOW]
It calles populate_dml_pipes which uses doubles to initialize.
Adding FPU protection avoids context switch and probable loss of vba context
as there is potential contention while drm debug logs are enabled.

Signed-off-by: CHANDAN VURDIGERE NATARAJ <chandan.vurdigerenataraj at amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c b/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c
index 826970f2bd0a..f27262417abe 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c
@@ -1750,7 +1750,9 @@ bool dcn31_validate_bandwidth(struct dc *dc,
 
 	BW_VAL_TRACE_COUNT();
 
+	DC_FP_START();
 	out = dcn30_internal_validate_bw(dc, context, pipes, &pipe_cnt, &vlevel, fast_validate);
+	DC_FP_END();
 
 	// Disable fast_validate to set min dcfclk in alculate_wm_and_dlg
 	if (pipe_cnt == 0)
-- 
2.25.1