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Date: Fri, 11 Mar 2016 10:48:02 +0100
From: Borislav Petkov <bp@alien8.de>
To: Ingo Molnar <mingo@kernel.org>,
        "Bryan O'Donoghue" <pure.logic@nexus-software.ie>
Cc: Andy Lutomirski <luto@amacapital.net>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Oleg Nesterov <oleg@redhat.com>,
        "Yu, Yu-cheng" <yu-cheng.yu@intel.com>
Subject: Re: Got FPU related warning on Intel Quark during boot
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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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