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Subject: Re: [Xen-devel] [PATCH] xen/x86: actually allocate legacy interrupts
 on PV guests
To: Stefano Stabellini <sstabellini@kernel.org>
References: <alpine.DEB.2.10.1604201413070.23110@sstabellini-ThinkPad-X260>
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Cc: David Vrabel <david.vrabel@citrix.com>, Juergen Gross <jgross@suse.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
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From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Message-ID: <5739D1DE.2000200@oracle.com>
Date: Mon, 16 May 2016 09:57:50 -0400
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On 05/16/2016 07:23 AM, Stefano Stabellini wrote:
> On Wed, 27 Apr 2016, Boris Ostrovsky wrote:
>> On 04/27/2016 09:40 AM, David Vrabel wrote:
>>> On 27/04/16 14:38, Boris Ostrovsky wrote:
>>>> int xen_nr_legacy_irqs()
>>>> {
>>>>      if (xen_hvm_domain())
>>>>          return nr_legacy_irqs();
>>>>      if (xen_initial_domain())
>>>>          return NR_IRQS_LEGACY;
>>>>      return 0;
>>>> }
>>> Yeah, if that does the right thing...
>> I think it will break xen_allocate_irq_gsi() again, unless we check for HVM
>> domain explicitly. Which would be ugly.
> I guess we all forgot about this patch, in the meantime the merge window
> has opened.
>
> Should we go ahead with:
>
> http://marc.info/?l=linux-kernel&m=146115812124261&w=2
>
> ?
> It might not be complete, but it is certainly an improvement.

Yes, I think what you have there is the best option. What I suggested
above won't work and adding another check for HVM domain in 
xen_allocate_irq_gsi() won't look good (although it does work).

It will need to go to stable as well (4.4+ ?)

-boris

>
> Otherwise, please submit proper patches ASAP. I don't think we want to
> delay this fix until 4.8.