s390/pci: query fmb length

Query the length of the fmb and abort fmb registration if the
size of the associated measurement block is too small.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 6611f79..4e31866 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -133,6 +133,7 @@ struct zpci_dev {
 	/* Function measurement block */
 	struct zpci_fmb *fmb;
 	u16		fmb_update;	/* update interval */
+	u16		fmb_length;
 	/* software counters */
 	atomic64_t allocated_pages;
 	atomic64_t mapped_pages;