Messages in this thread | | | Subject | Re: [PATCH 1/2] KVM: introduce __vmx_flush_tlb to handle specific vpid | From | Paolo Bonzini <> | Date | Fri, 25 Sep 2015 10:01:53 +0200 |
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On 24/09/2015 18:12, Bandan Das wrote: > Not sure myself what's the right thing to do but this may be undesirable > in a nested environment. Assuming the processor supports global invalidation > only, this seems like a easy way for the nested guest to invalidate *all* > mappings - even the L1 specific mappings.
It's not a great thing but it's already what happens if you do a global INVEPT (it calls vmx_flush_tlb, which results in a global INVVPID if the single-context variant is not supported).
Even without nested virt a single guest could slow down all other guests just by triggering frequent TLB flushes (e.g. by moving around a ROM BAR thousands of times per second).
It would help to know _which_ processors actually don't support single-context INVVPIDs...
Paolo
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