Messages in this thread | | | Subject | Re: [PATCH 2/2] x86/speculation: Support "Enhanced IBRS" on future CPUs | From | Paolo Bonzini <> | Date | Tue, 20 Feb 2018 12:43:37 +0100 |
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On 20/02/2018 01:00, Van De Ven, Arjan wrote: >>> 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...
No Arjan, this is just wrong. Well, I suppose it's right in the present tense with the IBRS mess on Skylake, but it's _not_ been true until last year.
Paolo
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