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Date: Fri, 13 Mar 2015 15:39:28 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@intel.com>, Ingo Molnar <mingo@kernel.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Pekka Riikonen <priikone@iki.fi>, Rik van Riel <riel@redhat.com>,
        Suresh Siddha <sbsiddha@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "Yu, Fenghua" <fenghua.yu@intel.com>,
        Quentin Casasnovas <quentin.casasnovas@oracle.com>
Subject: Re: [PATCH 2/4] x86/fpu: introduce restore_init_xstate()
Message-ID: <20150313143928.GB21603@redhat.com>
References: <54F74F59.5070107@intel.com> <20150311173346.GB5032@redhat.com> <20150311173429.GD5032@redhat.com> <20150313103406.GB31998@pd.tnic>
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On 03/13, Borislav Petkov wrote:
>
> > - It is not clear why we can't call setup_init_fpu_buf() unconditionally
> >   to always create init_xstate_buf().
>
> I also don't understand what the thought behind xstate_enable_boot_cpu()
> and eager_fpu_init_bp() - we do call xstate_enable_boot_cpu() and alloc
> init_xstate_buf and then when we come to
>
> eager_fpu_init
> |-> eager_fpu_init_bp
>
> we get to init it if not initted yet.
>
> When can that ever happen?

This too needs cleanups. But later ;)

Note that xstate_enable_boot_cpu is not called if !cpu_has_xsave, see the
check in xsave_init(). Howver, eagerfpu=on will force eager_fpu_init() which
calls eager_fpu_init_bp().

Btw, I was also going to kill eager_fpu_init_bp(). Probably I will send the
patch today.

> Applied, thanks.

Thanks!

Oleg.