Re: [PATCH v2 03/12] x86/pv: switch SWAPGS to ALTERNATIVE

[Borislav Petkov <bp@xxxxxxxxx>]

On Fri, Nov 20, 2020 at 12:46:21PM +0100, Juergen Gross wrote:
> SWAPGS is used only for interrupts coming from user mode or for
> returning to user mode. So there is no reason to use the PARAVIRT
> framework, as it can easily be replaced by an ALTERNATIVE depending
> on X86_FEATURE_XENPV.
> 
> There are several instances using the PV-aware SWAPGS macro in paths
> which are never executed in a Xen PV guest. Replace those with the
> plain swapgs instruction. For SWAPGS_UNSAFE_STACK the same applies.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
>  arch/x86/entry/entry_64.S             | 10 +++++-----
>  arch/x86/include/asm/irqflags.h       | 20 ++++++++------------
>  arch/x86/include/asm/paravirt.h       | 20 --------------------
>  arch/x86/include/asm/paravirt_types.h |  2 --
>  arch/x86/kernel/asm-offsets_64.c      |  1 -
>  arch/x86/kernel/paravirt.c            |  1 -
>  arch/x86/kernel/paravirt_patch.c      |  3 ---
>  arch/x86/xen/enlighten_pv.c           |  3 ---
>  8 files changed, 13 insertions(+), 47 deletions(-)

I love patches like this one! Give me more...

Reviewed-by: Borislav Petkov <bp@xxxxxxx>

-- 
Regards/Gruss,
    Boris.

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