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RE: [Xen-devel] [VTD][PATCH] interrupt remapping patch for xen 3.3

Actually I have a patch that modifies low level macros
io_apic_read()/io_apic_write() to call
io_apic_read_remap_rte/io_apic_write_remap_rte() if vt-d is enabled.

Since dom0 accesses io-apic hardware via these two macros, this should
not cause conflicts.  With these low level macros modified, the call to
gsi_remapping() will no longer be needed.

Let me know what you think about it.  I can send you a refreshed patch.


>-----Original Message-----
>From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx] 
>Sent: Thursday, January 24, 2008 11:39 PM
>To: Kay, Allen M; xen-devel@xxxxxxxxxxxxxxxxxxx
>Cc: Han, Weidong
>Subject: Re: [Xen-devel] [VTD][PATCH] interrupt remapping 
>patch for xen 3.3
>Okay, that only made a little sense to me. The main problem I have with
>fiddling with io-apic entries is that they're all actually under the
>management of dom0 kernel.
> -- Keir
>On 24/1/08 22:33, "Kay, Allen M" <allen.m.kay@xxxxxxxxx> wrote:
>> Interrupt remapping redirects ioapic/msi interrupt entries 
>to interrupt
>> remap table.  SID field in the Interrupt Remapping Table 
>Entry qualifies
>> the interrupt with BDF information of the ioapic/MSI devices.
>> Therefore the main value it adds for current Xen VT-d/PCI passthru is
>> that it protects hypervisor interrupts from malicious attacks from
>> guests with passthru devices.  Other benefits it can provide 
>is easier
>> IRQ rebalancing and extended APIC ID support.
>> Allen
>>> -----Original Message-----
>>> From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>>> Sent: Thursday, January 24, 2008 12:14 AM
>>> To: Kay, Allen M; xen-devel@xxxxxxxxxxxxxxxxxxx
>>> Cc: Han, Weidong
>>> Subject: Re: [Xen-devel] [VTD][PATCH] interrupt remapping
>>> patch for xen 3.3
>>> What exactly does irq remapping mean, and what are its 
>benefits in the
>>> current Xen VT-D architecture? It's really not at all clear
>>> what's going on
>>> from the current VT-D documentation.
>>> Since all interrupts get abstracted through Xen right now, if
>>> it's just an
>>> interrupt-line remapping then that doesn't seem very useful...
>>> -- Keir
>>> On 24/1/08 02:33, "Kay, Allen M" <allen.m.kay@xxxxxxxxx> wrote:
>>>> Attached patch remaps interrupt for passthru device if such HW is
>>>> detected on VT-d platforms.
>>>> Signed-off-by: Allen Kay <allen.m.kay@xxxxxxxxx>
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>> http://lists.xensource.com/xen-devel

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