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Re: [Xen-devel] [VTD][PATCH] Fix ISA IRQ alias issue

To: "Han, Weidong" <weidong.han@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [VTD][PATCH] Fix ISA IRQ alias issue
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Tue, 20 Nov 2007 16:19:36 +0000
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "Kay, Allen M" <allen.m.kay@xxxxxxxxx>
Delivery-date: Tue, 20 Nov 2007 08:20:32 -0800
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Thread-topic: [Xen-devel] [VTD][PATCH] Fix ISA IRQ alias issue
User-agent: Microsoft-Entourage/11.3.6.070618
hvm_set_pci_link_route dereferences hvm_irq->dpci without checking for NULL.

hvm_dpci_eoi tests guest_gsi in isairq_mask without checking < NR_ISAIRQS.

hvm_dpci_isairq_eoi can be a private vt-d function. All external callers can
continue to go through hvm_dpci_eoi.

link_mask doesn't look like a very useful field. Get rid of it?

isairq_mask isn't a great name. It's purpose is quite different from
dirq_mask for example. Can we come up with a better name for either of these
fields?

 -- Keir

On 17/11/07 05:15, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:

> Keir, attached patch adds ISA IRQ handling for EOI of ISA IRQs via
> IO-APIC, does it eliminate your concern?
> 
> -- Weidong
> 
> Keir Fraser wrote:
>> So what if a PCI-ISA IRQ is delivered via, and EOIed via, the IO-APIC?
>> 
>>  -- Keir
>> 
>> On 17/11/07 01:37, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:
>> 
>>> This patch doesn't change EOI of PCI-ISA IRQs via IO-APIC, it just
>>> uses a separate function to handle EOI of PCI-ISA IRQs via the PIC.
>>> Without this patch, assigning multiple devices to guest which uses
>>> PIC maybe results in disabling the IRQ.
>>> 
>>> -- Weidong
>>> 
>>> Keir Fraser wrote:
>>>> A concerning amount of code churn and I'm not clear it works for EOI
>>>> of PCI-ISA IRQs via the IO-APIC. This probably isn't for 3.2.0.
>>>> 
>>>>  -- Keir
>>>> 
>>>> On 15/11/07 06:32, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:
>>>> 
>>>>> When assign multiple devices to guest which uses PIC, ISA IRQ alias
>>>>> may occur. This patch splits ISA IRQ and GSI eoi function. In ISA
>>>>> IRQ eoi function, searches all assigned mirqs and does eoi for the
>>>>> corresponding mirqs which match the eoi ISA IRQ. Therefore fix ISA
>>>>> IRQ alias issue.
>>>>> 
>>>>> 
>>>>> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
>>>>> _______________________________________________
>>>>> Xen-devel mailing list
>>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>>> http://lists.xensource.com/xen-devel
>>>> 
>>>> 
>>>> 
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>> http://lists.xensource.com/xen-devel
> 



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