linux-kernel - Re: [PATCH v2] x86/xen: avoid warning in Xen pv guest with CONFIG_AMD_MEM

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Message-ID: <27d2b0bb-3232-a99b-a577-e61014dd04bc@suse.com>
Date:   Wed, 27 Jan 2021 14:59:08 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     Andrew Cooper <andrew.cooper3@...rix.com>,
        xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] x86/xen: avoid warning in Xen pv guest with
 CONFIG_AMD_MEM_ENCRYPT enabled

On 27.01.21 12:23, Andrew Cooper wrote:
> On 27/01/2021 10:26, Jürgen Groß wrote:
>> On 27.01.21 10:43, Andrew Cooper wrote:
>>> On 27/01/2021 09:38, Juergen Gross wrote:
>>>> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
>>>> index 4409306364dc..ca5ac10fcbf7 100644
>>>> --- a/arch/x86/xen/enlighten_pv.c
>>>> +++ b/arch/x86/xen/enlighten_pv.c
>>>> @@ -583,6 +583,12 @@ DEFINE_IDTENTRY_RAW(xenpv_exc_debug)
>>>>            exc_debug(regs);
>>>>    }
>>>>    +DEFINE_IDTENTRY_RAW(exc_xen_unknown_trap)
>>>> +{
>>>> +    /* This should never happen and there is no way to handle it. */
>>>> +    panic("Unknown trap in Xen PV mode.");
>>>
>>> Looks much better.  How about including regs->entry_vector here, just to
>>> short circuit the inevitable swearing which will accompany encountering
>>> this panic() ?
>>
>> You are aware the regs parameter is struct pt_regs *, not the Xen
>> struct cpu_user_regs *?
> 
> Yes, but I was assuming that they both contained the same information.
> 
>>
>> So I have no idea how I should get this information without creating
>> a per-vector handler.
> 
> Oh - that's dull.
> 
> Fine then.  Reviewed-by: Andrew Cooper <andrew.cooper3@...rix.com>
> 

I think I'll switch the panic() to printk(); BUG(); in order to have
more diagnostic data. Can I keep your R-b: with that modification?


Juergen

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