linux-kernel - [PATCH 11/23] x86/fpu: Add (__)make_fpregs

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Message-Id: <20181107194858.9380-12-bigeasy@linutronix.de>
Date:   Wed,  7 Nov 2018 20:48:46 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        kvm@...r.kernel.org, "Jason A. Donenfeld" <Jason@...c4.com>,
        Rik van Riel <riel@...riel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 11/23] x86/fpu: Add (__)make_fpregs_active helpers

From: Rik van Riel <riel@...riel.com>

Add helper function that ensures the floating point registers for
the current task are active. Use with preemption disabled.

Signed-off-by: Rik van Riel <riel@...riel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 arch/x86/include/asm/fpu/api.h      | 11 +++++++++++
 arch/x86/include/asm/fpu/internal.h | 26 ++++++++++++++++----------
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index a9caac9d4a729..8c03b42416656 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>
 
 /*
  * Careful: __kernel_fpu_begin/end() must be called with preempt disabled
@@ -27,6 +28,16 @@ extern void kernel_fpu_begin(void);
 extern void kernel_fpu_end(void);
 extern bool irq_fpu_usable(void);
 
+static inline void __fpregs_changes_begin(void)
+{
+	preempt_disable();
+}
+
+static inline void __fpregs_changes_end(void)
+{
+	preempt_enable();
+}
+
 /*
  * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
  *
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index d7f9e14c73c19..260cd4f4ba2bb 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -512,6 +512,20 @@ static inline void fpregs_activate(struct fpu *fpu)
 	trace_x86_fpu_regs_activated(fpu);
 }
 
+/*
+ * Load the FPU state for the current task. Call with preemption disabled.
+ */
+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);
+		else
+			copy_kernel_to_fpregs(&init_fpstate);
+	}
+	fpregs_activate(fpu);
+}
+
 /*
  * FPU state switching for scheduling.
  *
@@ -547,16 +561,8 @@ 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);
-			else
-				copy_kernel_to_fpregs(&init_fpstate);
-		}
-
-		fpregs_activate(new_fpu);
-	}
+	if (static_cpu_has(X86_FEATURE_FPU))
+		__fpregs_load_activate(new_fpu, cpu);
 }
 
 /*
-- 
2.19.1