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From:   "Bae, Chang Seok" <chang.seok.bae@intel.com>
To:     Thomas Gleixner <tglx@linutronix.de>
CC:     "bp@suse.de" <bp@suse.de>, "Lutomirski, Andy" <luto@kernel.org>,
        "mingo@kernel.org" <mingo@kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "Brown, Len" <len.brown@intel.com>,
        "lenb@kernel.org" <lenb@kernel.org>,
        "Hansen, Dave" <dave.hansen@intel.com>,
        "Macieira, Thiago" <thiago.macieira@intel.com>,
        "Liu, Jing2" <jing2.liu@intel.com>,
        "Shankar, Ravi V" <ravi.v.shankar@intel.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v10 05/28] x86/fpu/xstate: Add a new variable to indicate
 dynamic user states
Thread-Topic: [PATCH v10 05/28] x86/fpu/xstate: Add a new variable to indicate
 dynamic user states
Thread-Index: AQHXmcpyDgSn+PMdakuOT8LrEK8anqu+WZCAgAPA4oA=
Date:   Sun, 3 Oct 2021 22:35:51 +0000
Message-ID: <DC2E88A6-4CE8-4F10-B527-081EE147927A@intel.com>
References: <20210825155413.19673-1-chang.seok.bae@intel.com>
 <20210825155413.19673-6-chang.seok.bae@intel.com> <87bl486g1y.ffs@tglx>
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On Oct 1, 2021, at 06:16, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Wed, Aug 25 2021 at 08:53, Chang S. Bae wrote:
>> +/*
>> + * This represents user xstates, a subset of xfeatures_mask_all, saved =
in a
>> + * dynamic kernel XSAVE buffer.
>> + */
>> +u64 xfeatures_mask_user_dynamic __ro_after_init;
>> +
>> static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init =3D
>> 	{ [ 0 ... XFEATURE_MAX - 1] =3D -1};
>> static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init =3D
>> @@ -709,6 +715,7 @@ static int __init init_xstate_size(void)
>> static void fpu__init_disable_system_xstate(void)
>> {
>> 	xfeatures_mask_all =3D 0;
>> +	xfeatures_mask_user_dynamic =3D 0;
>=20
> It's zero at boot already, isn't it?

I thought of this as a safety net here when it was introduced.

But let me move it to patch13 [1] where the variable is updated.

Thanks,
Chang

[1] https://lore.kernel.org/lkml/20210825155413.19673-14-chang.seok.bae@int=
el.com/