Re: [PATCH] KVM: s390: vsie: retry SIE instruction on host intercepts

[David Hildenbrand <david@redhat.com>]

On 01.03.24 21:43, Eric Farman wrote:
> It's possible that SIE exits for work that the host needs to perform
> rather than something that is intended for the guest.
> 
> A Linux guest will ignore this intercept code since there is nothing
> for it to do, but a more robust solution would rewind the PSW back to
> the SIE instruction. This will transparently resume the guest once
> the host completes its work, without the guest needing to process
> what is effectively a NOP and re-issue SIE itself.

I recall that 0-intercepts are valid by the architecture. Further, I 
recall that there were some rather tricky corner cases where avoiding 
0-intercepts would not be that easy.

Now, it's been a while ago, and maybe I misremember. SoI'm trusting 
people with access to documentation can review this.

-- 
Cheers,

David / dhildenb