Comparing the XEN options:
--- /tmp/old 2019-02-01 20:31:53.351871571 +0200
+++ /tmp/new 2019-02-01 20:32:03.621872068 +0200
@@ -20,11 +20,14 @@
CONFIG_HVC_XEN=y
CONFIG_HVC_XEN_FRONTEND=y
CONFIG_XEN_WDT=y
+CONFIG_DRM_XEN=y
+CONFIG_DRM_XEN_FRONTEND=m
CONFIG_XEN_FBDEV_FRONTEND=y
+CONFIG_SND_XEN_FRONTEND=m
CONFIG_MMC_SDHCI_XENON=m
CONFIG_XEN_BALLOON=y
# CONFIG_XEN_SELFBALLOONING is not set
-CONFIG_XEN_SCRUB_PAGES=y
+CONFIG_XEN_SCRUB_PAGES_DEFAULT=y
CONFIG_XEN_DEV_EVTCHN=y
CONFIG_XEN_BACKEND=y
CONFIG_XENFS=y
@@ -32,10 +35,13 @@
CONFIG_XEN_SYS_HYPERVISOR=y
CONFIG_XEN_XENBUS_FRONTEND=y
CONFIG_XEN_GNTDEV=m
+CONFIG_XEN_GNTDEV_DMABUF=y
CONFIG_XEN_GRANT_DEV_ALLOC=m
+CONFIG_XEN_GRANT_DMA_ALLOC=y
CONFIG_SWIOTLB_XEN=y
CONFIG_XEN_TMEM=m
CONFIG_XEN_PCIDEV_BACKEND=m
+CONFIG_XEN_PVCALLS_FRONTEND=m
# CONFIG_XEN_PVCALLS_BACKEND is not set
CONFIG_XEN_PRIVCMD=y
CONFIG_XEN_ACPI_PROCESSOR=m
The new kernel only added options, so I'm not sure why it would have less functionality. I don't use Xen though.