[PATCH 143/208] x86/fpu: Simplify __save_fpu()

[Ingo Molnar]

__save_fpu() has this pattern:

		if (unlikely(system_state == SYSTEM_BOOTING))
			xsave_state_booting(&fpu->state.xsave);
		else
			xsave_state(&fpu->state.xsave);

... but it does not actually get called during system bootup.

So remove the complication and always call xsave_state().

To make sure this assumption is correct, add a WARN_ONCE()
debug check to xsave_state().

Reviewed-by: Borislav Petkov <bp@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/fpu/xsave.h | 2 ++
 arch/x86/kernel/fpu/core.c       | 5 +----
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/fpu/xsave.h b/arch/x86/include/asm/fpu/xsave.h
index a10e66582c1b..2f2ed322263f 100644
--- a/arch/x86/include/asm/fpu/xsave.h
+++ b/arch/x86/include/asm/fpu/xsave.h
@@ -133,6 +133,8 @@ static inline int xsave_state(struct xsave_struct *fx)
 	u32 hmask = mask >> 32;
 	int err = 0;
 
+	WARN_ON(system_state == SYSTEM_BOOTING);
+
 	/*
 	 * If xsaves is enabled, xsaves replaces xsaveopt because
 	 * it supports compact format and supervisor states in addition to
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 43689660d71c..a0e2b65745da 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -172,10 +172,7 @@ EXPORT_SYMBOL_GPL(irq_ts_restore);
 static void __save_fpu(struct fpu *fpu)
 {
 	if (use_xsave()) {
-		if (unlikely(system_state == SYSTEM_BOOTING))
-			xsave_state_booting(&fpu->state.xsave);
-		else
-			xsave_state(&fpu->state.xsave);
+		xsave_state(&fpu->state.xsave);
 	} else {
 		fpu_fxsave(fpu);
 	}
-- 
2.1.0

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