From 4bc6a4fca1f06bf4ae1d30e751f52e738c964110 Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Wed, 23 Aug 2023 14:57:47 +0800 Subject: [PATCH] x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4 commit 2c66ca3949dc701da7f4c9407f2140ae425683a5 upstream. 0-Day found a 34.6% regression in stress-ng's 'af-alg' test case, and bisected it to commit b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()"), which optimizes the FPU init order, and moves the CR4_OSXSAVE enabling into a later place: arch_cpu_finalize_init identify_boot_cpu identify_cpu generic_identify get_cpu_cap --> setup cpu capability ... fpu__init_cpu fpu__init_cpu_xstate cr4_set_bits(X86_CR4_OSXSAVE); As the FPU is not yet initialized the CPU capability setup fails to set X86_FEATURE_OSXSAVE. Many security module like 'camellia_aesni_avx_x86_64' depend on this feature and therefore fail to load, causing the regression. Cure this by setting X86_FEATURE_OSXSAVE feature right after OSXSAVE enabling. [ tglx: Moved it into the actual BSP FPU initialization code and added a comment ] Fixes: b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()") Reported-by: kernel test robot Signed-off-by: Feng Tang Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/202307192135.203ac24e-oliver.sang@intel.com Link: https://lore.kernel.org/lkml/20230823065747.92257-1-feng.tang@intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/fpu/xstate.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 80836b94189e..b897feb519ad 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -892,6 +892,14 @@ void __init fpu__init_system_xstate(void) setup_init_fpu_buf(); setup_xstate_comp_offsets(); setup_supervisor_only_offsets(); + + /* + * CPU capabilities initialization runs before FPU init. So + * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely + * functional, set the feature bit so depending code works. + */ + setup_force_cpu_cap(X86_FEATURE_OSXSAVE); + print_xstate_offset_size(); pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",