linux-kernel - Re: [PATCH] x86/entry: fix entry_INT80

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Message-ID: <2987196d-a5fd-a756-03f4-e1ddc41b5249@suse.com>
Date:   Tue, 16 Aug 2022 09:48:09 +0200
From:   Jan Beulich <jbeulich@...e.com>
To:     Juergen Gross <jgross@...e.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, stable@...r.kernel.org,
        xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/entry: fix entry_INT80_compat for Xen PV guests

On 16.08.2022 09:11, Juergen Gross wrote:
> Commit c89191ce67ef ("x86/entry: Convert SWAPGS to swapgs and remove
> the definition of SWAPGS") missed one use case of SWAPGS in
> entry_INT80_compat. Removing of the SWAPGS macro led to asm just
> using "swapgs", as it is accepting instructions in capital letters,
> too.
> 
> This in turn leads to splats in Xen PV guests like:
> 
> [   36.145223] general protection fault, maybe for address 0x2d: 0000 [#1] PREEMPT SMP NOPTI
> [   36.145794] CPU: 2 PID: 1847 Comm: ld-linux.so.2 Not tainted 5.19.1-1-default #1 openSUSE Tumbleweed f3b44bfb672cdb9f235aff53b57724eba8b9411b
> [   36.146608] Hardware name: HP ProLiant ML350p Gen8, BIOS P72 11/14/2013
> [   36.148126] RIP: e030:entry_INT80_compat+0x3/0xa3
> 
> Fix that by open coding this single instance of the SWAPGS macro.
> 
> Cc: <stable@...r.kernel.org> # 5.19
> Fixes: c89191ce67ef ("x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS")
> Signed-off-by: Juergen Gross <jgross@...e.com>

Reviewed-by: Jan Beulich <jbeulich@...e.com>