Re: [patch V2 00/52] x86/fpu: Spring cleaning and PKRU sanitizing

Yu, Yu-cheng
2021-06-16T00:50:18Z

On 6/14/2021 8:44 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.
>
> 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 V1 which can be found here:
>
> https://lore.kernel.org/r/20210611161523.508908024@linutronix.de
>
> Changes vs. V1:
>
> - Fix the broken init_fpstate initialization
>
> - Make xstate copy to ptrace work correctly
>
> - Sanitize the regset functions more and get rid of
> fpstate_sanitize_xstate().
>
> - Addressed review comments
>
> - Picked up tags
>
> Thanks,
>
> tglx
> ---
> arch/x86/events/intel/lbr.c | 6
> arch/x86/include/asm/fpu/internal.h | 179 +++-------
> 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 | 29 -
> arch/x86/kernel/fpu/core.c | 242 +++++++++----
> arch/x86/kernel/fpu/init.c | 4
> arch/x86/kernel/fpu/regset.c | 177 ++++-----
> arch/x86/kernel/fpu/signal.c | 59 +--
> arch/x86/kernel/fpu/xstate.c | 620 ++++++++++++++---------------------
> arch/x86/kernel/process.c | 19 +
> arch/x86/kernel/process_64.c | 28 +
> 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
> 22 files changed, 818 insertions(+), 853 deletions(-)
>
>

I applied shadow stack, IBT on top of this series, and ran routine
tests. All passed with one small change to patch #45 (see reply to that
one).

Thanks,
Yu-cheng