linux-kernel - Re: [PATCH 2/4] x86/xen: use specific Xen pv interrupt entry for DF

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Date:   Mon, 16 Nov 2020 17:14:49 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     xen-devel <xen-devel@...ts.xenproject.org>,
        X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        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>
Subject: Re: [PATCH 2/4] x86/xen: use specific Xen pv interrupt entry for DF

On 16.11.20 17:12, Andy Lutomirski wrote:
> On Mon, Nov 16, 2020 at 7:23 AM Juergen Gross <jgross@...e.com> wrote:
>>
>> Xen PV guests don't use IST. For double fault interrupts switch to
>> the same model as NMI.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>>   arch/x86/include/asm/idtentry.h | 3 +++
>>   arch/x86/xen/enlighten_pv.c     | 8 +++++++-
>>   arch/x86/xen/xen-asm.S          | 2 +-
>>   3 files changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
>> index 3505c0396fa5..b35825392547 100644
>> --- a/arch/x86/include/asm/idtentry.h
>> +++ b/arch/x86/include/asm/idtentry.h
>> @@ -611,6 +611,9 @@ DECLARE_IDTENTRY_RAW(X86_TRAP_DB,   xenpv_exc_debug);
>>
>>   /* #DF */
>>   DECLARE_IDTENTRY_DF(X86_TRAP_DF,       exc_double_fault);
>> +#ifdef CONFIG_XEN_PV
>> +DECLARE_IDTENTRY_RAW_ERRORCODE(X86_TRAP_DF,    xenpv_exc_double_fault);
>> +#endif
>>
>>   /* #VC */
>>   #ifdef CONFIG_AMD_MEM_ENCRYPT
>> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
>> index 9f5e44c1f70a..803fbcb398c4 100644
>> --- a/arch/x86/xen/enlighten_pv.c
>> +++ b/arch/x86/xen/enlighten_pv.c
>> @@ -571,6 +571,12 @@ DEFINE_IDTENTRY_RAW(xenpv_exc_nmi)
>>          exc_nmi(regs);
>>   }
>>
>> +DEFINE_IDTENTRY_RAW_ERRORCODE(xenpv_exc_double_fault)
>> +{
>> +       /* On Xen PV, DF doesn't use IST.  The C part is the sane as native. */
> 
> I would like to think that code is sane, but you probably meant "same".

Oh, this is the result of copy and paste. Now we have two sane
functions. :-)


Juergen

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