[openstack-dev] [nova] SR-IOV and IOMMU check

Luohao (brian) brian.luohao at huawei.com
Sat Mar 29 01:46:15 UTC 2014

This is the approach mentioned by linux-kvm.org


3. reboot and verify that your system has IOMMU support

AMD Machine
dmesg | grep AMD-Vi
     AMD-Vi: Enabling IOMMU at 0000:00:00.2 cap 0x40
     AMD-Vi: Lazy IO/TLB flushing enabled
     AMD-Vi: Initialized for Passthrough Mode
Intel Machine
dmesg | grep -e DMAR -e IOMMU
     DMAR:DRHD base: 0x000000feb03000 flags: 0x0
     IOMMU feb03000: ver 1:0 cap c9008020e30260 ecap 1000

-----Original Message-----
From: Steve Gordon [mailto:sgordon at redhat.com] 
Sent: Saturday, March 29, 2014 3:37 AM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [nova] SR-IOV and IOMMU check

----- Original Message -----
> Hi, all
> Currently openstack can support SR-IOV device pass-through (at least 
> there are some patches for this), but the prerequisite to this is both 
> IOMMU and SR-IOV must be enabled correctly, it seems there is not a 
> robust way to check this in openstack, I have implemented a way to do 
> this and hope it can be committed into upstream, this can help find 
> the issue beforehand, instead of letting kvm report the issue "no 
> IOMMU found" until the VM is started. I didn't find an appropriate 
> place to put into this, do you think this is necessary? Where can it 
> be put into? Welcome your advice and thank you in advance.

What's the mechanism you are using on the host side to determine that IOMMU is supported/enabled?



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