From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: Re: [PATCH v2] xen: x86_32: do not enable iterrupts
	when returning from exception in interrupt context
Date: Fri, 2 Sep 2011 09:40:32 -0400
Message-ID: <20110902134032.GA6064@dumpdata.com>
References: <4E5EB794.7050909@goop.org>
	<1314877615-18280-1-git-send-email-imammedo@redhat.com>
	<4E5FB700.1070908@goop.org> <4E60914F.7080208@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <xen-devel-bounces@lists.xensource.com>
Content-Disposition: inline
In-Reply-To: <4E60914F.7080208@redhat.com>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Igor Mammedov <imammedo@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org
List-Id: xen-devel@lists.xenproject.org

On Fri, Sep 02, 2011 at 10:18:23AM +0200, Igor Mammedov wrote:
> 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@redhat.com>
> >>Signed-off-by: Jeremy Fitzhardinge<jeremy@goop.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?

That is OK.  I fixed it up in the git commit. Thanks for finding this one!