[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH 3/4] x86/pv: switch SWAPGS to ALTERNATIVE

To: Juergen Gross <jgross@xxxxxxxx>
From: Andy Lutomirski <luto@xxxxxxxxxx>
Date: Mon, 16 Nov 2020 08:17:29 -0800
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, X86 ML <x86@xxxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, Linux Virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Deep Shah <sdeep@xxxxxxxxxx>, "VMware, Inc." <pv-drivers@xxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>
Delivery-date: Mon, 16 Nov 2020 16:17:48 +0000
List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On Mon, Nov 16, 2020 at 7:23 AM Juergen Gross <jgross@xxxxxxxx> 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.

Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>

References:
- [PATCH 0/4] x86/xen: do some paravirt cleanup
  - From: Juergen Gross
- [PATCH 3/4] x86/pv: switch SWAPGS to ALTERNATIVE
  - From: Juergen Gross

Prev by Date: Re: [PATCH 2/4] x86/xen: use specific Xen pv interrupt entry for DF
Next by Date: Re: [PATCH 4/4] x86/xen: drop USERGS_SYSRET64 paravirt call
Previous by thread: [PATCH 3/4] x86/pv: switch SWAPGS to ALTERNATIVE
Next by thread: [PATCH 4/4] x86/xen: drop USERGS_SYSRET64 paravirt call
Index(es):
- Date
- Thread

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.