spapr: register dummy ICPs later
Some older machine types create more ICPs than needed. We hence need to register up to xics_max_server_number() dummy ICPs to accomodate the migration of these machine types. Recent VSMT rework changed xics_max_server_number() to return DIV_ROUND_UP(max_cpus * spapr->vsmt, smp_threads) instead of DIV_ROUND_UP(max_cpus * kvmppc_smt_threads(), smp_threads); The change is okay but it requires spapr->vsmt to be set, which isn't the case with the current code. This causes the formula to return zero and we don't create dummy ICPs. This breaks migration of older guests as reported here: https://bugzilla.redhat.com/show_bug.cgi?id=1549087 The dummy ICP workaround doesn't really have a dependency on XICS itself. But it does depend on proper VCPU id numbering and it must be applied before creating vCPUs (ie, creating real ICPs). So this patch moves the workaround to spapr_init_cpus(), which already assumes VSMT to be set. Fixes: 72194664 ("spapr: use spapr->vsmt to compute VCPU ids") Reported-by: NLukas Doktor <ldoktor@redhat.com> Signed-off-by: NGreg Kurz <groug@kaod.org> Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
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