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Message-ID: <20201127113156.GB13163@zn.tnic>
Date: Fri, 27 Nov 2020 12:31:56 +0100
From: Borislav Petkov <bp@...en8.de>
To: Juergen Gross <jgross@...e.com>
Cc: xen-devel@...ts.xenproject.org, x86@...nel.org,
linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org, peterz@...radead.org,
luto@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Deep Shah <sdeep@...are.com>,
"VMware, Inc." <pv-drivers@...are.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Stefano Stabellini <sstabellini@...nel.org>
Subject: Re: [PATCH v2 03/12] x86/pv: switch SWAPGS to ALTERNATIVE
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@...e.com>
> Acked-by: Andy Lutomirski <luto@...nel.org>
> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
> 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@...e.de>
--
Regards/Gruss,
Boris.
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