From: Jared Rossi <jrossi@linux.ibm.com>

We are going to link the SLOF libc into the s390-ccw.img, and this
libc needs more memory for providing space for malloc() and friends.
Thus bump the memory size that we reserve for the bios to 3 MiB
instead of only 2 MiB. While we're at it, add a proper check that
there is really enough memory assigned to the machine before blindly
using it.

Co-authored by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>

---
 hw/s390x/ipl.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index dd71689642..c33a044d1d 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -45,6 +45,7 @@
 #define INITRD_PARM_START               0x010408UL
 #define PARMFILE_START                  0x001000UL
 #define ZIPL_IMAGE_START                0x009000UL
+#define BIOS_MAX_SIZE                   0x300000UL
 #define IPL_PSW_MASK                    (PSW_MASK_32 | PSW_MASK_64)
 
 static bool iplb_extended_needed(void *opaque)
@@ -144,7 +145,14 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
      * even if an external kernel has been defined.
      */
     if (!ipl->kernel || ipl->enforce_bios) {
-        uint64_t fwbase = (MIN(ms->ram_size, 0x80000000U) - 0x200000) & ~0xffffUL;
+        uint64_t fwbase;
+
+        if (ms->ram_size < BIOS_MAX_SIZE) {
+            error_setg(errp, "not enough RAM to load the BIOS file");
+            return;
+        }
+
+        fwbase = (MIN(ms->ram_size, 0x80000000U) - BIOS_MAX_SIZE) & ~0xffffUL;
 
         bios_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, ipl->firmware);
         if (bios_filename == NULL) {
-- 
2.45.1