linux-kernel - [patch 0/8] x86/fpu: Consolidate the size and feature information (part 3)

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Date:   Fri, 15 Oct 2021 01:09:28 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Chang S. Bae" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Subject: [patch 0/8] x86/fpu: Consolidate the size and feature information (part 3)

This is the third part of the effort to support AMX. The second part can be
found here:

     https://lore.kernel.org/r/20211013142847.120153383@linutronix.de

With AMX the FPU register state buffer which is part of
task_struct::thread::fpu is not going to be extended unconditionally for
all tasks on an AMX enabled system as that would waste minimum 8K per task.

AMX provides a mechanism to trap on first use. That trap will be utilized
to allocate a larger register state buffer when the task (process) has
permissions to use it. The default buffer task_struct will only carry
states up to AVX512.

This needs more information than what is provided now with various
variables. 

The original approach was to just add more variables, but it's simpler to
stick this into data structures. 

The current series:

 - creates a data structure which carries the necessary information:
   default and maximum features and sizes.

 - instantiates and initializes one for kernel information and one for user
   space

 - converts all users of the old variables

 - removes the now unused old variables

It's a straight forward conversion which should not introduce any
functional changes.

This series is based on:

   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/fpu-2

and also available from git:

   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/fpu-3

The full series with part 4 on top is available here:

   git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/fpu

Thanks,

	tglx
---
 include/asm/fpu/types.h  |   39 ++++++++++
 include/asm/fpu/xstate.h |   47 +-----------
 kernel/fpu/context.h     |    6 -
 kernel/fpu/core.c        |   37 +++++++---
 kernel/fpu/init.c        |   46 +++++-------
 kernel/fpu/internal.h    |    2 
 kernel/fpu/regset.c      |    2 
 kernel/fpu/signal.c      |   11 +-
 kernel/fpu/xstate.c      |  173 +++++++++++++++++++++++++----------------------
 kernel/fpu/xstate.h      |   15 +++-
 10 files changed, 205 insertions(+), 173 deletions(-)