[PATCH 41/66] drm/amd/display: Disable migration to ensure consistency of per-CPU variable

[Qingqing Zhuo]

From: Tianci Yin <tianci.yin at amd.com>

[why]
Since the variable fpu_recursion_depth is per-CPU type, it has one copy
on each CPU, thread migration causes data consistency issue, then the
call trace shows up. And preemption disabling can't prevent migration.

[how]
Disable migration to ensure consistency of fpu_recursion_depth.

Reviewed-by: Aurabindo Pillai <aurabindo.pillai at amd.com>
Signed-off-by: Tianci Yin <tianci.yin at amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
index 1743ca0a3641..c42aa947c969 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
@@ -89,6 +89,7 @@ void dc_fpu_begin(const char *function_name, const int line)
 
 	if (*pcpu == 1) {
 #if defined(CONFIG_X86)
+		migrate_disable();
 		kernel_fpu_begin();
 #elif defined(CONFIG_PPC64)
 		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
@@ -129,6 +130,7 @@ void dc_fpu_end(const char *function_name, const int line)
 	if (*pcpu <= 0) {
 #if defined(CONFIG_X86)
 		kernel_fpu_end();
+		migrate_enable();
 #elif defined(CONFIG_PPC64)
 		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
 			disable_kernel_vsx();
-- 
2.34.1