Re: [PATCH v3] x86/bugs: Only harden syscalls when needed

[Borislav Petkov]

On Tue, Apr 16, 2024 at 04:02:21PM -0700, Josh Poimboeuf wrote:
> Syscall hardening (i.e., converting the syscall indirect branch to a
> series of direct branches) may cause performance regressions in certain
> scenarios.  Only use the syscall hardening when indirect branches are
> considered unsafe.
> 
> Fixes: 1e3ad78334a6 ("x86/syscall: Don't force use of indirect calls for system calls")
> Reviewed-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---
> v3:
> - fix X86_FEATURE_INDIRECT_SAFE value
> 
>  arch/x86/entry/common.c            | 15 ++++++++++++---
>  arch/x86/entry/syscall_32.c        | 11 +----------
>  arch/x86/entry/syscall_64.c        |  6 ------
>  arch/x86/entry/syscall_x32.c       |  7 ++++++-
>  arch/x86/include/asm/cpufeatures.h |  1 +
>  arch/x86/include/asm/syscall.h     |  8 +++++++-
>  arch/x86/kernel/cpu/bugs.c         | 31 +++++++++++++++++++++++++++++-
>  7 files changed, 57 insertions(+), 22 deletions(-)

I poked at this a bit and can't find anything that I can complain about
so

Acked-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>

I'll pick it up into urgent if no one complains soon.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette