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x86/fpu: Add an __fpregs_load_activate() internal helper

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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
This commit is contained in:
Rik van Riel 2019-04-03 18:41:38 +02:00 committed by Borislav Petkov
parent 0169f53e0d
commit 4ee91519e1
2 changed files with 25 additions and 8 deletions
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11
arch/x86/include/asm/fpu/api.h
View File

@ -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.
*

22
arch/x86/include/asm/fpu/internal.h
View File

@ -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);
}
/*