From 954436989cc550dd91aab98363240c9c0a4b7e23 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 23 Jun 2021 14:02:21 +0200 Subject: [PATCH] x86/fpu: Remove PKRU handling from switch_fpu_finish() PKRU is already updated and the xstate is not longer the proper source of information. [ bp: Use cpu_feature_enabled() ] Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121456.708180184@linutronix.de --- arch/x86/include/asm/fpu/internal.h | 34 ++++------------------------- 1 file changed, 4 insertions(+), 30 deletions(-) diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 2a484f5f2413..528a86826f95 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -523,39 +523,13 @@ static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu) */ /* - * Load PKRU from the FPU context if available. Delay loading of the - * complete FPU state until the return to userland. + * Delay loading of the complete FPU state until the return to userland. + * PKRU is handled separately. */ static inline void switch_fpu_finish(struct fpu *new_fpu) { - u32 pkru_val = init_pkru_value; - struct pkru_state *pk; - - if (!static_cpu_has(X86_FEATURE_FPU)) - return; - - set_thread_flag(TIF_NEED_FPU_LOAD); - - if (!cpu_feature_enabled(X86_FEATURE_OSPKE)) - return; - - /* - * PKRU state is switched eagerly because it needs to be valid before we - * return to userland e.g. for a copy_to_user() operation. - */ - if (!(current->flags & PF_KTHREAD)) { - /* - * If the PKRU bit in xsave.header.xfeatures is not set, - * then the PKRU component was in init state, which means - * XRSTOR will set PKRU to 0. If the bit is not set then - * get_xsave_addr() will return NULL because the PKRU value - * in memory is not valid. This means pkru_val has to be - * set to 0 and not to init_pkru_value. - */ - pk = get_xsave_addr(&new_fpu->state.xsave, XFEATURE_PKRU); - pkru_val = pk ? pk->pkru : 0; - } - __write_pkru(pkru_val); + if (cpu_feature_enabled(X86_FEATURE_FPU)) + set_thread_flag(TIF_NEED_FPU_LOAD); } #endif /* _ASM_X86_FPU_INTERNAL_H */