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Message-ID: <4473dcbd-38fa-bc19-d665-673dfc763f8f@intel.com>
Date: Mon, 21 Jun 2021 09:15:43 -0700
From: "Yu, Yu-cheng" <yu-cheng.yu@...el.com>
To: Thomas Gleixner <tglx@...utronix.de>,
LKML <linux-kernel@...r.kernel.org>
Cc: Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Fenghua Yu <fenghua.yu@...el.com>,
Tony Luck <tony.luck@...el.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Borislav Petkov <bp@...e.de>,
Peter Zijlstra <peterz@...radead.org>,
Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [patch V3 00/66] x86/fpu: Spring cleaning and PKRU sanitizing
On 6/18/2021 7:18 AM, Thomas Gleixner wrote:
> The main parts of this series are:
>
> - Yet more bug fixes
>
> - Simplification and removal/replacement of redundant and/or
> overengineered code.
>
> - Name space cleanup as the existing names were just a permanent source
> of confusion.
>
> - Clear seperation of user ABI and kernel internal state handling.
>
> - Removal of PKRU from being XSTATE managed in the kernel because PKRU
> has to be eagerly restored on context switch and keeping it in sync
> in the xstate buffer is just pointless overhead and fragile.
>
> The kernel still XSAVEs PKRU on context switch but the value in the
> buffer is not longer used and never restored from the buffer.
>
> This still needs to be cleaned up, but the series is already 40+
> patches large and the cleanup of this is not a functional problem.
>
> The functional issues of PKRU management are fully addressed with the
> series as is.
>
> - Cleanup of fpu signal restore
>
> - Make the fast path self contained. Handle #PF directly and skip
> the slow path on any other exception as that will just end up
> with the same result that the frame is invalid. This allows
> the compiler to optimize the slow path out for 64bit kernels
> w/o ia32 emulation.
>
> - Reduce code duplication and unnecessary operations
>
>
> It applies on top of
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git master
>
> and is also available via git:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/fpu
>
> This is a follow up to V2 which can be found here:
>
> https://lore.kernel.org/r/20210614154408.673478623@linutronix.de
>
> Changes vs. V2:
>
> - Fixed the testing fallout (Dave, Kan)
>
> - Fixed a few issues found by myself when going through the lot
> with a fine comb, especially MXCSR handling
>
> - Drop the FNSAVE optimizations
>
> - Cleanup of signal restore
>
> - Addressed review comments, mostly comments and a hopefully better
> naming scheme which now just uses the instruction names and
> consolidates everything else on save/restore so it's close to the way
> how the hardware works.
>
> - A few cleanups and simplifications on the way (mostly regset related).
>
> - Picked up tags
>
> With the above I'm not intending to do any further surgery on that
> code at the moment, though there is still room for improvement which
> can and has to be worked on when new bits are added.
>
> Thanks,
Run all my tests again, and all pass.
Thanks,
Yu-cheng
>
> tglx
> ---
> arch/x86/events/intel/lbr.c | 6
> arch/x86/include/asm/fpu/internal.h | 211 +++-------
> arch/x86/include/asm/fpu/xstate.h | 70 ++-
> arch/x86/include/asm/pgtable.h | 57 --
> arch/x86/include/asm/pkeys.h | 9
> arch/x86/include/asm/pkru.h | 62 +++
> arch/x86/include/asm/processor.h | 9
> arch/x86/include/asm/special_insns.h | 14
> arch/x86/kernel/cpu/common.c | 34 -
> arch/x86/kernel/fpu/core.c | 276 +++++++------
> arch/x86/kernel/fpu/init.c | 15
> arch/x86/kernel/fpu/regset.c | 220 ++++++-----
> arch/x86/kernel/fpu/signal.c | 423 +++++++++------------
> arch/x86/kernel/fpu/xstate.c | 693 ++++++++++++++---------------------
> arch/x86/kernel/process.c | 22 -
> arch/x86/kernel/process_64.c | 28 +
> arch/x86/kernel/traps.c | 5
> arch/x86/kvm/svm/sev.c | 1
> arch/x86/kvm/x86.c | 56 +-
> arch/x86/mm/extable.c | 2
> arch/x86/mm/fault.c | 2
> arch/x86/mm/pkeys.c | 22 -
> include/linux/pkeys.h | 4
> 23 files changed, 1060 insertions(+), 1181 deletions(-)
>
>
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