s390x/pci: reflect proper maxstbl for groups of interpreted devices

The maximum supported store block length might be different depending
on whether the instruction is interpretively executed (firmware-reported
maximum) or handled via userspace intercept (host kernel API maximum).
Choose the best available value during group creation.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Message-Id: <20220902172737.170349-8-mjrosato@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

hw/s390x/s390-pci-vfio.c

@@ -213,7 +213,11 @@ static void s390_pci_read_group(S390PCIBusDevice *pbdev,
         resgrp->msia = cap->msi_addr;
         resgrp->mui = cap->mui;
         resgrp->i = cap->noi;
-        resgrp->maxstbl = cap->maxstbl;
+        if (pbdev->interp && hdr->version >= 2) {
+            resgrp->maxstbl = cap->imaxstbl;
+        } else {
+            resgrp->maxstbl = cap->maxstbl;
+        }
         resgrp->version = cap->version;
         resgrp->dtsm = ZPCI_DTSM;
     }