[PATCH qemu v6 5/6] spapr: Allow changing offset for -kernel image

[Alexey Kardashevskiy <aik@ozlabs.ru>]

This allows moving the kernel in the guest memory. The option is useful
for step debugging (as Linux is linked at 0x0); it also allows loading
grub which is normally linked to run at 0x20000.

This uses the existing kernel address by default.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 include/hw/ppc/spapr.h |  1 +
 hw/ppc/spapr.c         | 38 +++++++++++++++++++++++++++++++-------
 2 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 3b50f36c338a..32e831a395ae 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -164,6 +164,7 @@ struct SpaprMachineState {
     void *fdt_blob;
     long kernel_size;
     bool kernel_le;
+    uint64_t kernel_addr;
     uint32_t initrd_base;
     long initrd_size;
     uint64_t rtc_offset; /* Now used only during incoming migration */
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 60153bf0b771..b59e9dc360fe 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1054,7 +1054,7 @@ static void spapr_dt_chosen(SpaprMachineState *spapr, void *fdt)
     }
 
     if (spapr->kernel_size) {
-        uint64_t kprop[2] = { cpu_to_be64(KERNEL_LOAD_ADDR),
+        uint64_t kprop[2] = { cpu_to_be64(spapr->kernel_addr),
                               cpu_to_be64(spapr->kernel_size) };
 
         _FDT(fdt_setprop(fdt, chosen, "qemu,boot-kernel",
@@ -1242,7 +1242,8 @@ void *spapr_build_fdt(SpaprMachineState *spapr, bool reset, size_t space)
     /* Build memory reserve map */
     if (reset) {
         if (spapr->kernel_size) {
-            _FDT((fdt_add_mem_rsv(fdt, KERNEL_LOAD_ADDR, spapr->kernel_size)));
+            _FDT((fdt_add_mem_rsv(fdt, spapr->kernel_addr,
+                                  spapr->kernel_size)));
         }
         if (spapr->initrd_size) {
             _FDT((fdt_add_mem_rsv(fdt, spapr->initrd_base,
@@ -1270,7 +1271,9 @@ void *spapr_build_fdt(SpaprMachineState *spapr, bool reset, size_t space)
 
 static uint64_t translate_kernel_address(void *opaque, uint64_t addr)
 {
-    return (addr & 0x0fffffff) + KERNEL_LOAD_ADDR;
+    SpaprMachineState *spapr = opaque;
+
+    return (addr & 0x0fffffff) + spapr->kernel_addr;
 }
 
 static void emulate_spapr_hypercall(PPCVirtualHypervisor *vhyp,
@@ -2947,14 +2950,15 @@ static void spapr_machine_init(MachineState *machine)
         uint64_t lowaddr = 0;
 
         spapr->kernel_size = load_elf(kernel_filename, NULL,
-                                      translate_kernel_address, NULL,
+                                      translate_kernel_address, spapr,
                                       NULL, &lowaddr, NULL, NULL, 1,
                                       PPC_ELF_MACHINE, 0, 0);
         if (spapr->kernel_size == ELF_LOAD_WRONG_ENDIAN) {
             spapr->kernel_size = load_elf(kernel_filename, NULL,
-                                          translate_kernel_address, NULL, NULL,
+                                          translate_kernel_address, spapr, NULL,
                                           &lowaddr, NULL, NULL, 0,
-                                          PPC_ELF_MACHINE, 0, 0);
+                                          PPC_ELF_MACHINE,
+                                          0, 0);
             spapr->kernel_le = spapr->kernel_size > 0;
         }
         if (spapr->kernel_size < 0) {
@@ -2968,7 +2972,7 @@ static void spapr_machine_init(MachineState *machine)
             /* Try to locate the initrd in the gap between the kernel
              * and the firmware. Add a bit of space just in case
              */
-            spapr->initrd_base = (KERNEL_LOAD_ADDR + spapr->kernel_size
+            spapr->initrd_base = (spapr->kernel_addr + spapr->kernel_size
                                   + 0x1ffff) & ~0xffff;
             spapr->initrd_size = load_image_targphys(initrd_filename,
                                                      spapr->initrd_base,
@@ -3214,6 +3218,18 @@ static void spapr_set_vsmt(Object *obj, Visitor *v, const char *name,
     visit_type_uint32(v, name, (uint32_t *)opaque, errp);
 }
 
+static void spapr_get_kernel_addr(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
+{
+    visit_type_uint64(v, name, (uint64_t *)opaque, errp);
+}
+
+static void spapr_set_kernel_addr(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
+{
+    visit_type_uint64(v, name, (uint64_t *)opaque, errp);
+}
+
 static char *spapr_get_ic_mode(Object *obj, Error **errp)
 {
     SpaprMachineState *spapr = SPAPR_MACHINE(obj);
@@ -3319,6 +3335,14 @@ static void spapr_instance_init(Object *obj)
     object_property_add_bool(obj, "vfio-no-msix-emulation",
                              spapr_get_msix_emulation, NULL, NULL);
 
+    object_property_add(obj, "kernel-addr", "uint64", spapr_get_kernel_addr,
+                        spapr_set_kernel_addr, NULL, &spapr->kernel_addr,
+                        &error_abort);
+    object_property_set_description(obj, "kernel-addr",
+                                    stringify(KERNEL_LOAD_ADDR)
+                                    " for -kernel is the default",
+                                    NULL);
+    spapr->kernel_addr = KERNEL_LOAD_ADDR;
     /* The machine class defines the default interrupt controller mode */
     spapr->irq = smc->irq;
     object_property_add_str(obj, "ic-mode", spapr_get_ic_mode,
-- 
2.17.1