Re: [PATCH] KVM: s390: vsie: retry SIE when unable to get vsie_page

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Mon, 05 Jan 2026 10:46:53 -0500
Eric Farman <farman@linux.ibm.com> wrote:

> On Mon, 2026-01-05 at 13:41 +0100, Janosch Frank wrote:
> > On 12/17/25 04:01, Eric Farman wrote:  
> > > SIE may exit because of pending host work, such as handling an interrupt,
> > > in which case VSIE rewinds the guest PSW such that it is transparently
> > > resumed (see Fixes tag). There is still one scenario where those conditions

can you add a few words to (very briefly) explain what the scenario is?

> > > are not present, but that the VSIE processor returns with effectively rc=0,
> > > resulting in additional (and unnecessary) guest work to be performed.
> > > 
> > > For this case, rewind the guest PSW as we do in the other non-error exits.
> > > 
> > > Fixes: 33a729a1770b ("KVM: s390: vsie: retry SIE instruction on host intercepts")
> > > Signed-off-by: Eric Farman <farman@linux.ibm.com>  
> > 
> > This is purely cosmetic to have all instances look the same, right?  
> 
> Nope, I can take this path with particularly high I/O loads on the system, which ends up
> (incorrectly) sending the intercept to the guest.

this is a good candidate for the explanation I mentioned above :)


(the patch itself looks fine)