From f17b168734c0fe47343a7502d012266a051f9942 Mon Sep 17 00:00:00 2001 From: "Chang S. Bae" Date: Wed, 8 Jun 2022 09:47:47 -0700 Subject: x86/fpu: Add a helper to prepare AMX state for low-power CPU idle When a CPU enters an idle state, a non-initialized AMX register state may be the cause of preventing a deeper low-power state. Other extended register states whether initialized or not do not impact the CPU idle state. The new helper can ensure the AMX state is initialized before the CPU is idle, and it will be used by the intel idle driver. Check the AMX_TILE feature bit before using XGETBV1 as a chain of dependencies was established via cpuid_deps[]: AMX->XFD->XGETBV1. Signed-off-by: Chang S. Bae Signed-off-by: Dave Hansen Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20220608164748.11864-2-chang.seok.bae@intel.com --- arch/x86/include/asm/fpu/api.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/include/asm/fpu/api.h') diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index 6b0f31fb53f7..503a577814b2 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -164,4 +164,6 @@ static inline bool fpstate_is_confidential(struct fpu_guest *gfpu) /* prctl */ extern long fpu_xstate_prctl(int option, unsigned long arg2); +extern void fpu_idle_fpregs(void); + #endif /* _ASM_X86_FPU_API_H */ -- cgit v1.2.3