[Xen-devel] [PATCH 4.1] x86: fix emuirq regression from XSA-21 fix (was: Re: [PATCH] xen: reuse the same pirq allocated when driver load first time)

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.06.13 at 07:33, DuanZhenzhong <zhenzhong.duan@xxxxxxxxxx> wrote:
> Stefano Stabellini wrote:
>> On Mon, 24 Jun 2013, Zhenzhong Duan wrote:
>>> Could you have a look if there is something wrong in xen side of clearing 
>>> the mapping?
>>
>> What I am saying is that the error you are getting:
>>
>> pt_msix_disable: Unbind msix with pirq 67, gvec 0
>> pt_msix_disable: Unmap msix with pirq 67
>> pt_msix_disable: Error: Unmapping of MSI-X failed. [00:04.0]
>>
>> cannot be caused by domain_pirq_to_emuirq(d, pirq) returning
>> IRQ_UNBOUND.
>> So, why are you getting this error? What is failing?
>> I am ready to believe the problem is in Xen but Without understanding
>> why you are getting the error it's hard to find a solution.
>>   
> I found the reason, you are looking at xen-unstable, I was working with 
> 4.1.30-OVM, it has patch of CVE-2012-4536 / XSA-21.
> That patch set ret to -EINVAL initially. After remove that line, unmap 
> succeed.

Removing that line certainly isn't right. The proper fix is the one
below/attached.

Jan

****************************************************
x86: fix emuirq regression from XSA-21 fix

The XSA-21 patch broke the assumption of "ret" being zero prior to the
IRQ_UNBOUND check.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -243,6 +243,8 @@ static int physdev_unmap_pirq(struct phy
         spin_lock(&d->event_lock);
         if ( domain_pirq_to_emuirq(d, unmap->pirq) != IRQ_UNBOUND )
             ret = unmap_domain_pirq_emuirq(d, unmap->pirq);
+        else
+            ret = 0;
         spin_unlock(&d->event_lock);
         if ( unmap->domid == DOMID_SELF || ret )
             goto free_domain;

Attachment: x86-xsa21-emuirq-fix.patch
Description: Text document

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