RE: [PATCH 2/2] x86/speculation: Support "Enhanced IBRS" on future CPUs

[Van De Ven, Arjan]

> On Mon, 19 Feb 2018 23:42:24 +0000, "Van De Ven, Arjan" said:
> 
> > the guest is not the problem; guests obviously will already honor if Enhanced
> > IBRS is enumerated. The problem is mixed migration pools where the
> hypervisor
> > may need to decide to not pass this enumeration through to the guest.
> 
> For bonus points:  What should happen to a VM that is live migrated from one
> hypervisor to another, and the hypervisors have different IBRS support?

Doctor Doctor it hurts when I do this....

Migration tends to only work between HV's that are relatively homogeneous, that's nothing new... folks who run clouds or bigger pools know this obviously.