Commit 9ad93fe3 authored Oct 04, 2016 by Rik van Riel Committed by Ingo Molnar Oct 07, 2016

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@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-10-git-send-email-riel@redhat.com

Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 66f314ef

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

+8 −14

Original line number	Diff line number	Diff line
		@@ -581,15 +581,9 @@ 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);

		/* Don't change CR0.TS if we just switch! */
		if (fpu.preload) {
		fpregs_activate(new_fpu);
		trace_x86_fpu_regs_activated(new_fpu);
		prefetch(&new_fpu->state);
		}
		} else {
		} else
		old_fpu->last_cpu = -1;

		if (fpu.preload) {
		if (fpregs_state_valid(new_fpu, cpu))
		fpu.preload = 0;
		@@ -597,7 +591,7 @@ switch_fpu_prepare(struct fpu old_fpu, struct fpu new_fpu, int cpu)
		prefetch(&new_fpu->state);
		fpregs_activate(new_fpu);
		}
		}

		return fpu;
		}