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drm/amdkfd: Preserve wave state after instruction fetch MEM_VIOL

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If instruction fetch fails the wave cannot be halted and returned to
the shader without raising MEM_VIOL again. Currently the wave is
terminated if this occurs, but this loses information about the cause
of the fault. The debugger would prefer the faulting wave state to be
context-saved.

Poll inside the trap handler until TRAPSTS.SAVECTX indicates context
save is ready. Exit the poll loop and complete the remainder of the
exception handler, then return to the shader. The next instruction
fetch will be from the trap handler and not the faulting PC. Context
save will then deschedule the wave and save its state.

Signed-off-by: Jay Cornwall <Jay.Cornwall@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Jay Cornwall 2019-01-31 11:38:18 -06:00 committed by Alex Deucher
parent 2db2f25959
commit 157e586dc9
2 changed files with 14 additions and 6 deletions
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10
drivers/gpu/drm/amd/amdkfd/cwsr_trap_handler.h
View file

@ -274,15 +274,17 @@ static const uint32_t cwsr_trap_gfx8_hex[] = {
static const uint32_t cwsr_trap_gfx9_hex[] = {
0xbf820001, 0xbf82015d,
0xbf820001, 0xbf820161,
0xb8f8f802, 0x89788678,
0xb8f1f803, 0x866eff71,
0x00000400, 0xbf850037,
0x00000400, 0xbf85003b,
0x866eff71, 0x00000800,
0xbf850003, 0x866eff71,
0x00000100, 0xbf840008,
0x00000100, 0xbf84000c,
0x866eff78, 0x00002000,
0xbf840001, 0xbf810000,
0xbf840005, 0xbf8e0010,
0xb8eef803, 0x866eff6e,
0x00000400, 0xbf84fffb,
0x8778ff78, 0x00002000,
0x80ec886c, 0x82ed806d,
0xb8eef807, 0x866fff6e,

10
drivers/gpu/drm/amd/amdkfd/cwsr_trap_handler_gfx9.asm
View file

@ -266,10 +266,16 @@ if (!EMU_RUN_HACK)
L_HALT_WAVE:
// If STATUS.HALT is set then this fault must come from SQC instruction fetch.
// We cannot prevent further faults so just terminate the wavefront.
// We cannot prevent further faults. Spin wait until context saved.
s_and_b32 ttmp2, s_save_status, SQ_WAVE_STATUS_HALT_MASK
s_cbranch_scc0 L_NOT_ALREADY_HALTED
s_endpgm
L_WAIT_CTX_SAVE:
s_sleep 0x10
s_getreg_b32 ttmp2, hwreg(HW_REG_TRAPSTS)
s_and_b32 ttmp2, ttmp2, SQ_WAVE_TRAPSTS_SAVECTX_MASK
s_cbranch_scc0 L_WAIT_CTX_SAVE
L_NOT_ALREADY_HALTED:
s_or_b32 s_save_status, s_save_status, SQ_WAVE_STATUS_HALT_MASK