linux-kernel - Re: Got FPU related warning on Intel Quark during boot

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Message-ID: <20160311094802.GA4312@pd.tnic>
Date:	Fri, 11 Mar 2016 10:48:02 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Ingo Molnar <mingo@...nel.org>,
	Bryan O'Donoghue <pure.logic@...us-software.ie>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Oleg Nesterov <oleg@...hat.com>,
	"Yu, Yu-cheng" <yu-cheng.yu@...el.com>
Subject: Re: Got FPU related warning on Intel Quark during boot

On Fri, Mar 11, 2016 at 10:08:40AM +0100, Ingo Molnar wrote:
> So yes, this needs to be fixed too.

Yes indeed. So the diff below seems to work with Bryan's simple test
case.

Bryan, can you confirm on your box pls?

---
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index dea8e76d60c6..8e37cc8a539a 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -474,8 +474,10 @@ static inline void copy_init_fpstate_to_fpregs(void)
 {
 	if (use_xsave())
 		copy_kernel_to_xregs(&init_fpstate.xsave, -1);
-	else
+	else if (static_cpu_has(X86_FEATURE_FXSR))
 		copy_kernel_to_fxregs(&init_fpstate.fxsave);
+	else
+		copy_kernel_to_fregs(&init_fpstate.fsave);
 }
 
 /*
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index e12cc0ad368e..c835f61d5feb 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -134,7 +134,7 @@ static void __init fpu__init_system_generic(void)
 	 * Set up the legacy init FPU context. (xstate init might overwrite this
 	 * with a more modern format, if the CPU supports it.)
 	 */
-	fpstate_init_fxstate(&init_fpstate.fxsave);
+	fpstate_init(&init_fpstate);
 
 	fpu__init_system_mxcsr();
 }

---

Thanks.

-- 
Regards/Gruss,
    Boris.

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