From 4ee91519e1dccc175665fe24bb20a47c6053575c Mon Sep 17 00:00:00 2001
From: Rik van Riel <riel@surriel.com>
Date: Wed, 3 Apr 2019 18:41:38 +0200
Subject: 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
---
 arch/x86/include/asm/fpu/api.h | 11 +++++++++++
 1 file changed, 11 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 b56d504af654..73e684160f35 100644
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -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.
  *
-- 
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