s390x: keep hint on virtio managing size

The s390x virtio bus keeps management information on virtio after the top
of the guest's RAM. We need to be able to tell the guest the size of its
RAM (without virtio stuff), but also be able to trap when the guest accesses
RAM outside of its scope (including virtio stuff).

So we need a variable telling us the size of the virtio stuff, so we can
calculate the highest available RAM address from that.

While at it, also increase the maximum number of virtio pages, so we play
along well with more recent kernels that spawn a ridiculous number of virtio
console adapters.

Signed-off-by: Alexander Graf <agraf@suse.de>

hw/s390-virtio-bus.c

@@ -60,6 +60,9 @@ static const VirtIOBindings virtio_s390_bindings;
 
 static ram_addr_t s390_virtio_device_num_vq(VirtIOS390Device *dev);
 
+/* length of VirtIO device pages */
+const target_phys_addr_t virtio_size = S390_DEVICE_PAGES * TARGET_PAGE_SIZE;
+
 VirtIOS390Bus *s390_virtio_bus_init(ram_addr_t *ram_size)
 {
     VirtIOS390Bus *bus;

hw/s390-virtio-bus.h

@@ -33,7 +33,7 @@
 #define VIRTIO_VQCONFIG_LEN		24
 
 #define VIRTIO_RING_LEN			(TARGET_PAGE_SIZE * 3)
-#define S390_DEVICE_PAGES		256
+#define S390_DEVICE_PAGES		512
 
 typedef struct VirtIOS390Device {
     DeviceState qdev;

target-s390x/cpu.h

@@ -310,6 +310,9 @@ static inline void kvm_s390_interrupt_internal(CPUState *env, int type,
 #endif
 CPUState *s390_cpu_addr2state(uint16_t cpu_addr);
 
+/* from s390-virtio-bus */
+extern const target_phys_addr_t virtio_size;
+
 #ifndef KVM_S390_SIGP_STOP
 #define KVM_S390_SIGP_STOP              0
 #define KVM_S390_PROGRAM_INT            0