x86/fpu: Add an __fpregs_load_activate() internal helper (4ee91519) · Commits · 戴 / test

Add a helper function that ensures the floating point registers for the current task are active. Use with preemption disabled. While at it, add fpregs_lock/unlock() helpers too, to be used in later patches. [ bp: Add a comment about its intended usage. ] Signed-off-by:

Rik van Riel <riel@surriel.com> Signed-off-by:

Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by:

Borislav Petkov <bp@suse.de> Reviewed-by:

Dave Hansen <dave.hansen@intel.com> Reviewed-by:

Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Aubrey Li <aubrey.li@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: "Jason A. Donenfeld" <Jason@zx2c4.com> Cc: kvm ML <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190403164156.19645-10-bigeasy@linutronix.de

arch/x86/include/asm/fpu/api.h

+11 −0

Original line number	Diff line number	Diff line
		@@ -10,6 +10,7 @@

		#ifndef _ASM_X86_FPU_API_H
		#define _ASM_X86_FPU_API_H
		#include <linux/preempt.h>

		/*
		* Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
		@@ -22,6 +23,16 @@ extern void kernel_fpu_begin(void);
		extern void kernel_fpu_end(void);
		extern bool irq_fpu_usable(void);

		static inline void fpregs_lock(void)
		{
		preempt_disable();
		}

		static inline void fpregs_unlock(void)
		{
		preempt_enable();
		}

		/*
		* Query the presence of one or more xfeatures. Works on any legacy CPU as well.
		*

arch/x86/include/asm/fpu/internal.h

+14 −8

Original line number	Diff line number	Diff line
		@@ -484,6 +484,18 @@ static inline void fpregs_activate(struct fpu *fpu)
		trace_x86_fpu_regs_activated(fpu);
		}

		/*
		* Internal helper, do not use directly. Use switch_fpu_return() instead.
		*/
		static inline void __fpregs_load_activate(struct fpu *fpu, int cpu)
		{
		if (!fpregs_state_valid(fpu, cpu)) {
		if (current->mm)
		copy_kernel_to_fpregs(&fpu->state);
		fpregs_activate(fpu);
		}
		}

		/*
		* FPU state switching for scheduling.
		*
		@@ -522,14 +534,8 @@ switch_fpu_prepare(struct fpu *old_fpu, int cpu)
		*/
		static inline void switch_fpu_finish(struct fpu *new_fpu, int cpu)
		{
		if (static_cpu_has(X86_FEATURE_FPU)) {
		if (!fpregs_state_valid(new_fpu, cpu)) {
		if (current->mm)
		copy_kernel_to_fpregs(&new_fpu->state);
		}

		fpregs_activate(new_fpu);
		}
		if (static_cpu_has(X86_FEATURE_FPU))
		__fpregs_load_activate(new_fpu, cpu);
		}

		/*

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