* PCI passthrough in nested kvm
@ 2012-01-06 4:50 Tian Fang
2012-01-06 15:35 ` Alex Williamson
0 siblings, 1 reply; 2+ messages in thread
From: Tian Fang @ 2012-01-06 4:50 UTC (permalink / raw)
To: kvm
Hi,
Nested kvm is supported. Wondering if a PCI device is able to be
passed through into the nested kvm. Could some experts share some
insides?
Thx,
Tian Fang
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: PCI passthrough in nested kvm
2012-01-06 4:50 PCI passthrough in nested kvm Tian Fang
@ 2012-01-06 15:35 ` Alex Williamson
0 siblings, 0 replies; 2+ messages in thread
From: Alex Williamson @ 2012-01-06 15:35 UTC (permalink / raw)
To: Tian Fang; +Cc: kvm
On Thu, 2012-01-05 at 23:50 -0500, Tian Fang wrote:
> Hi,
>
> Nested kvm is supported. Wondering if a PCI device is able to be
> passed through into the nested kvm. Could some experts share some
> insides?
No, there's no iommu exposed to the L1 guest, so there's no way to
program the iommu for the L2 guest. You would also be bouncing
interrupts from the host to the L1 guest to the L2 guest, so you could
expect a performance hit with each level you add.
Alex
^ permalink raw reply [flat|nested] 2+ messages in thread
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