linux-kernel - [tip:x86/fpu] x86/fpu: Split old & new FPU code paths

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Message-ID: <tip-9ad93fe35aff616fca4e2b9581fdeed498605f9e@git.kernel.org>
Date:   Fri, 7 Oct 2016 02:47:20 -0700
From:   tip-bot for Rik van Riel <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     riel@...hat.com, oleg@...hat.com, brgerst@...il.com, hpa@...or.com,
        peterz@...radead.org, quentin.casasnovas@...cle.com,
        tglx@...utronix.de, mingo@...nel.org, linux-kernel@...r.kernel.org,
        torvalds@...ux-foundation.org, jpoimboe@...hat.com,
        dvlasenk@...hat.com, dave.hansen@...ux.intel.com, luto@...nel.org,
        bp@...en8.de, fenghua.yu@...el.com
Subject: [tip:x86/fpu] x86/fpu: Split old & new FPU code paths

Commit-ID:  9ad93fe35aff616fca4e2b9581fdeed498605f9e
Gitweb:     http://git.kernel.org/tip/9ad93fe35aff616fca4e2b9581fdeed498605f9e
Author:     Rik van Riel <riel@...hat.com>
AuthorDate: Tue, 4 Oct 2016 20:34:38 -0400
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 7 Oct 2016 11:14:43 +0200

x86/fpu: Split old & new FPU code paths

Now that CR0.TS is no longer being manipulated, we can simplify
switch_fpu_prepare() by no longer nesting the handling of new_fpu
inside the two branches for the old_fpu.

Signed-off-by: Rik van Riel <riel@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@...cle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: pbonzini@...hat.com
Link: http://lkml.kernel.org/r/1475627678-20788-10-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/fpu/internal.h | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index d0324bc..1dcb29e 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -581,23 +581,17 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
 		/* But leave fpu_fpregs_owner_ctx! */
 		old_fpu->fpregs_active = 0;
 		trace_x86_fpu_regs_deactivated(old_fpu);
+	} else
+		old_fpu->last_cpu = -1;
 
-		/* Don't change CR0.TS if we just switch! */
-		if (fpu.preload) {
-			fpregs_activate(new_fpu);
-			trace_x86_fpu_regs_activated(new_fpu);
+	if (fpu.preload) {
+		if (fpregs_state_valid(new_fpu, cpu))
+			fpu.preload = 0;
+		else
 			prefetch(&new_fpu->state);
-		}
-	} else {
-		old_fpu->last_cpu = -1;
-		if (fpu.preload) {
-			if (fpregs_state_valid(new_fpu, cpu))
-				fpu.preload = 0;
-			else
-				prefetch(&new_fpu->state);
-			fpregs_activate(new_fpu);
-		}
+		fpregs_activate(new_fpu);
 	}
+
 	return fpu;
 }