[qemu-s390x] [PATCH] s390x/ipl: Try to detect Linux vs non Linux for initial IPL PSW

[Christian Borntraeger]

Right now the IPL device always starts from address 0x10000 (the usual
Linux entry point). To run other guests (e.g. test programs) it is
useful to use the IPL PSW from address 0. We can use the Linux magic
at 0x10008 to decide.

Signed-off-by: Christian Borntraeger <address@hidden>
Acked-by: Jason J. Herne <address@hidden>
---
 hw/s390x/ipl.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index 150f6c0582..c0fed26f03 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -104,7 +104,9 @@ static uint64_t bios_translate_addr(void *opaque, uint64_t 
srcaddr)
 static void s390_ipl_realize(DeviceState *dev, Error **errp)
 {
     S390IPLState *ipl = S390_IPL(dev);
-    uint64_t pentry = KERN_IMAGE_START;
+    uint64_t *iplpsw;
+    uint64_t pentry;
+    char *magic;
     int kernel_size;
     Error *err = NULL;
 
@@ -156,6 +158,17 @@ static void s390_ipl_realize(DeviceState *dev, Error 
**errp)
                                NULL, 1, EM_S390, 0, 0);
         if (kernel_size < 0) {
             kernel_size = load_image_targphys(ipl->kernel, 0, ram_size);
+            /* if this is Linux use KERN_IMAGE_START */
+            magic = rom_ptr(0x10008);
+            if (magic && !memcmp(magic, "S390EP", 6)) {
+                pentry = KERN_IMAGE_START;
+            } else {
+                /* if not Linux use the IPL PSW */
+                iplpsw = rom_ptr(0);
+                if (iplpsw) {
+                    pentry = *iplpsw & 0x7fffffffUL;
+                }
+            }
         }
         if (kernel_size < 0) {
             error_setg(&err, "could not load kernel '%s'", ipl->kernel);
-- 
2.14.2