| From | "Chang S. Bae" <> | Subject | [PATCH v5 21/28] x86/fpu/amx: Initialize child's AMX state | Date | Sun, 23 May 2021 12:32:52 -0700 |
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Assure that a forked child starts AMX registers in the INIT-state.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Reviewed-by: Len Brown <len.brown@intel.com> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- Changes from v4: * Added as a new patch. This was missing on previous versions. --- arch/x86/kernel/fpu/core.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 016c3adebec3..cccfeafe81e5 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -285,6 +285,10 @@ int fpu__copy(struct task_struct *dst, struct task_struct *src) fpregs_unlock(); + /* AMX state is volatile, children do not inherit it. */ + if (xfeatures_mask_all & XFEATURE_MASK_XTILE) + dst_fpu->state->xsave.header.xfeatures &= ~(XFEATURE_MASK_XTILE); + set_tsk_thread_flag(dst, TIF_NEED_FPU_LOAD); trace_x86_fpu_copy_src(src_fpu); -- 2.17.1
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