linux-kernel - Re: [PATCH v2] xen: x86_32: do not enable iterrupts when returning from exception in interrupt context

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Message-ID: <4E60914F.7080208@redhat.com>
Date:	Fri, 02 Sep 2011 10:18:23 +0200
From:	Igor Mammedov <imammedo@...hat.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
CC:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	konrad.wilk@...cle.com
Subject: Re: [PATCH v2] xen: x86_32: do not enable iterrupts when returning
 from exception in interrupt context

On 09/01/2011 06:46 PM, Jeremy Fitzhardinge wrote:
> On 09/01/2011 04:46 AM, Igor Mammedov wrote:
>> If vmalloc page_fault happens inside of interrupt handler with interrupts
>> disabled then on exit path from exception handler when there is no pending
>> interrupts, the following code (arch/x86/xen/xen-asm_32.S:112):
>>
>> 	cmpw $0x0001, XEN_vcpu_info_pending(%eax)
>> 	sete XEN_vcpu_info_mask(%eax)
>>
>> will enable interrupts even if they has been previously disabled according to
>> eflags from the bounce frame (arch/x86/xen/xen-asm_32.S:99)
>>
>> 	testb $X86_EFLAGS_IF>>8, 8+1+ESP_OFFSET(%esp)
>> 	setz XEN_vcpu_info_mask(%eax)
>>
>> Solution is in setting XEN_vcpu_info_mask only when it should be set
>> according to
>> 	cmpw $0x0001, XEN_vcpu_info_pending(%eax)
>> but not clearing it if there isn't any pending events.
>>
>> Reproducer for bug is attached to RHBZ 707552
>>
>> Signed-off-by: Igor Mammedov<imammedo@...hat.com>
>> Signed-off-by: Jeremy Fitzhardinge<jeremy@...p.org>
>
> One nit, this should be acked-by or reviewed-by, not signed-off-by,
> since the patch isn't passing through my hands.
>
>      J

I'm new to this stuff, would you like me to re-post it?
Next time will do it right.

-------
Thanks,
    Igor
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