Messages in this thread | | | Subject | Re: [PATCH v3 9/9] KVM: Move instrumentation-safe annotations for enter/exit to x86 code | From | Christian Borntraeger <> | Date | Wed, 21 Apr 2021 10:09:11 +0200 |
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On 16.04.21 00:21, Sean Christopherson wrote: > Drop the instrumentation_{begin,end}() annonations from the common KVM > guest enter/exit helpers, and massage the x86 code as needed to preserve > the necessary annotations. x86 is the only architecture whose transition > flow is tagged as noinstr, and more specifically, it is the only > architecture for which instrumentation_{begin,end}() can be non-empty. > > No other architecture supports CONFIG_STACK_VALIDATION=y, and s390 is the > only other architecture that support CONFIG_DEBUG_ENTRY=y. For > instrumentation annontations to be meaningful, both aformentioned configs > must be enabled. > > Letting x86 deal with the annotations avoids unnecessary nops by > squashing back-to-back instrumention-safe sequences.
We have considered implementing objtool for s390. Not sure where we stand and if we will do this or not. Sven/Heiko?
So maybe drop this patch until every other arch agrees that there are no plans to implement this.
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