[Qemu-devel] [PATCH] fix xen hvm direct kernel boot

[Chunyan Liu <cyliu@suse.com>]

Since commit a1666142: acpi-build: make ROMs RAM blocks resizeable,
xen HVM direct kernel boot failed. Xen HVM direct kernel boot will
insert a linuxboot.bin or multiboot.bin to /genroms, before this
commit, in acpi_setup, for rom linuxboot.bin/multiboot.bin, it
only needs 0x20000 size; after the commit, it will reserve x16
size for resize, that is 0x200000 size. It causes xen_ram_alloc
failed due to running out of memory.

To resolve it, either:
1. keep using original rom size instead of max size, don't reserve x16 size.
2. guest maxmem needs to be increased. (commit c1d322e6 "xen-hvm: increase
   maxmem before calling xc_domain_populate_physmap" solved the problem for
   a time, by accident. But then it is reverted in commit ffffbb369 due to
   other problem.)

For 2, more discussion is needed about howto. So this patch tries 1, to
use unresizable rom size in xen case in rom_set_mr.

Signed-off-by: Chunyan Liu <cyliu@suse.com>
---
 hw/core/loader.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index c049957..5150101 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -55,6 +55,7 @@
 #include "exec/address-spaces.h"
 #include "hw/boards.h"
 #include "qemu/cutils.h"
+#include "hw/xen/xen.h"
 
 #include <zlib.h>
 
@@ -818,7 +819,10 @@ static void *rom_set_mr(Rom *rom, Object *owner, const char *name)
     void *data;
 
     rom->mr = g_malloc(sizeof(*rom->mr));
-    memory_region_init_resizeable_ram(rom->mr, owner, name,
+    if (xen_enabled())
+        memory_region_init_ram(rom->mr, owner, name, rom->datasize, &error_fatal);
+    else
+        memory_region_init_resizeable_ram(rom->mr, owner, name,
                                       rom->datasize, rom->romsize,
                                       fw_cfg_resized,
                                       &error_fatal);
-- 
1.8.5.6