IOMMU setting

IOMMU setting

[Eric Liu]

Is there a quick way to check if system has IOMMU enabled in Linux?
 
I saw the following messages in /var/log/messages:
 
Apr  3 21:03:16 kernel: PCI-DMA: Disabling AGP.
Apr  3 21:03:16 kernel: PCI-DMA: aperture base @ f4000000 size 65536 KB
Apr  3 21:03:16 kernel: init_memory_mapping: 00000000f4000000-00000000f8000000
Apr  3 21:03:16 kernel: last_map_addr: f8000000 end: f8000000
Apr  3 21:03:16 kernel: PCI-DMA: using GART IOMMU.
Apr  3 21:03:16 kernel: PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture
 
 
Does this mean IOMMU is enabed? And i don't need anything like iommu=force in boot option, right?
 
CPU I used is the latest AMD Opteron Quad-core cpus. I didn't see any IOMMU setting option in BIOS, only enabling virtulization option is there. Is this the only option we need to enable?
 
Thanks
Eric
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Re: IOMMU setting

[Muli Ben-Yehuda]

On Sat, Apr 04, 2009 at 12:16:50AM +0000, Eric Liu wrote:
> 
> Is there a quick way to check if system has IOMMU enabled in Linux?
>  
> I saw the following messages in /var/log/messages:
>  
> Apr  3 21:03:16 kernel: PCI-DMA: Disabling AGP.
> Apr  3 21:03:16 kernel: PCI-DMA: aperture base @ f4000000 size 65536 KB
> Apr  3 21:03:16 kernel: init_memory_mapping: 00000000f4000000-00000000f8000000
> Apr  3 21:03:16 kernel: last_map_addr: f8000000 end: f8000000
> Apr  3 21:03:16 kernel: PCI-DMA: using GART IOMMU.
> Apr  3 21:03:16 kernel: PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture
>  
> Does this mean IOMMU is enabed? And i don't need anything like
> iommu=force in boot option, right?

It means that you are running on an AMD system, and that this system
has a GART. You need an isolation-capable IOMMU such as Intel's VT-d
for KVM in-tree device passthrough.

Cheers,
Muli
-- 
Muli Ben-Yehuda | muli@il.ibm.com | +972-4-8281080
Manager, Virtualization and Systems Architecture
Master Inventor, IBM Haifa Research Laboratory

SYSTOR 2009---The Israeli Experimental Systems Conference
http://www.haifa.il.ibm.com/conferences/systor2009/

RE: IOMMU setting

[Eric Liu]

Yes it is AMD system, however KVM website does mention AMD iommu support KVM device passthrough.
I want to make sure my system has this capability. 


Regards
Eric

----------------------------------------
> Date: Sat, 4 Apr 2009 21:18:23 +0300
> From: muli@il.ibm.com
> To: ericliu2008@hotmail.com
> CC: kvm@vger.kernel.org
> Subject: Re: IOMMU setting
>
> On Sat, Apr 04, 2009 at 12:16:50AM +0000, Eric Liu wrote:
>>
>> Is there a quick way to check if system has IOMMU enabled in Linux?
>>
>> I saw the following messages in /var/log/messages:
>>
>> Apr 3 21:03:16 kernel: PCI-DMA: Disabling AGP.
>> Apr 3 21:03:16 kernel: PCI-DMA: aperture base @ f4000000 size 65536 KB
>> Apr 3 21:03:16 kernel: init_memory_mapping: 00000000f4000000-00000000f8000000
>> Apr 3 21:03:16 kernel: last_map_addr: f8000000 end: f8000000
>> Apr 3 21:03:16 kernel: PCI-DMA: using GART IOMMU.
>> Apr 3 21:03:16 kernel: PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture
>>
>> Does this mean IOMMU is enabed? And i don't need anything like
>> iommu=force in boot option, right?
>
> It means that you are running on an AMD system, and that this system
> has a GART. You need an isolation-capable IOMMU such as Intel's VT-d
> for KVM in-tree device passthrough.
>
> Cheers,
> Muli
> --
> Muli Ben-Yehuda | muli@il.ibm.com | +972-4-8281080
> Manager, Virtualization and Systems Architecture
> Master Inventor, IBM Haifa Research Laboratory
>
> SYSTOR 2009---The Israeli Experimental Systems Conference
> http://www.haifa.il.ibm.com/conferences/systor2009/

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Re: IOMMU setting

[Muli Ben-Yehuda]

On Sun, Apr 05, 2009 at 05:14:44PM +0000, Eric Liu wrote:
> 
> Yes it is AMD system, however KVM website does mention AMD iommu
> support KVM device passthrough.  I want to make sure my system has
> this capability.

That's 'AMD IOMMU', as opposed to AMD GART, which is not an
isolation-capable IOMMU. I don't know if any chipsets with AMD's IOMMU
have been released yet.

Cheers,
Muli
-- 
Muli Ben-Yehuda | muli@il.ibm.com | +972-4-8281080
Manager, Virtualization and Systems Architecture
Master Inventor, IBM Haifa Research Laboratory

SYSTOR 2009---The Israeli Experimental Systems Conference
http://www.haifa.il.ibm.com/conferences/systor2009/