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RE: [Xen-devel] [VTD][PATCH] Support intra-domain shared interrupt

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [VTD][PATCH] Support intra-domain shared interrupt
From: "Han, Weidong" <weidong.han@xxxxxxxxx>
Date: Mon, 5 Nov 2007 16:16:26 +0800
Cc: "Kay, Allen M" <allen.m.kay@xxxxxxxxx>
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Thread-topic: [Xen-devel] [VTD][PATCH] Support intra-domain shared interrupt
Keir Fraser wrote:
> The two cases of hvm_dpci_eoi() (timeout versus non-timeout) have very
> little code in common. Should be two different functions instead of
> adding a cryptic final bool argument.
> 

will cleanup it.

> xmalloc() and list_add() should usually be accompanied with a
> destructing list_del() and xfree(). So this patch leaks memory.
> 

will fix it.

> And why is intra-domain sharing harder (or at least different) to
> deal with than inter-domain? Is this real physical IRQ sharing that's
> a problem, or sharing of the virtual GSI?
> 

Real physical sharing is a problem. Guest irq is generated from
device/intx, so two shared physical interrupt devices will be mapped to
two different guest irqs. Current data structure hvm_irq_dpci_mapping
doesn't consider this situation, mirq[i] contains only one device and
corresponding guest irq, need to add a list to contain multiple devices
whice share physical interrupt. What's more, we need to deal with
intra-domain shared interrupt injection and eoi specially.


> 
> On 5/11/07 05:35, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:
> 
>> Inter-domain shared interrupt has been supported by timeout method,
>> but it still doesn't support intra-domain shared interrupt, that is
>> assigning multiple devices which share a physical irq to the same
>> domain. This patch implements intra-domain shared interrupt support.
>> In addition, this patch maps link to guest device/intx instead of
>> directly mapping isairq in pt_irq_create_bind_vtd(), because at this
>> point the isairqs got from pci_link are always 0.
>> 
>> Note that assigning multiple devices to guests which uses PIC to
>> handle interrupts may be failed, because different links possibly
>> connect to same irq. 
>> 
>> 
>> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel

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