[Qemu-devel] [PATCH v6 6/7] exec: report error when memory < hpagesize

[Hu Tao]

Report error when memory < hpagesize in file_ram_alloc() so callers can
handle the error.

This patch fix a problem that if user adds a memory-backend-file object
using object_add command, specifying a size that is less than huge page
size, qemu will core dump with message:

  Bad ram offset fffffffffffff000
  Aborted (core dumped)

with this patch, qemu reports error message like:

  qemu-system-x86_64: -object 
memory-backend-file,mem-path=/hugepages,id=mem-file0,size=1M: memory
  size 0x100000 must be equal to or larger than huge page size 0x200000

Signed-off-by: Hu Tao <address@hidden>
---
 exec.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/exec.c b/exec.c
index accba00..50cd510 100644
--- a/exec.c
+++ b/exec.c
@@ -1024,9 +1024,9 @@ static void *file_ram_alloc(RAMBlock *block,
     char *filename;
     char *sanitized_name;
     char *c;
-    void *area;
+    void *area = NULL;
     int fd;
-    unsigned long hpagesize;
+    uint64_t hpagesize;
 
     hpagesize = gethugepagesize(path);
     if (!hpagesize) {
@@ -1034,7 +1034,10 @@ static void *file_ram_alloc(RAMBlock *block,
     }
 
     if (memory < hpagesize) {
-        return NULL;
+        error_setg(errp, "memory size 0x" RAM_ADDR_FMT " must be equal to "
+                   "or larger than huge page size 0x%" PRIx64,
+                   memory, hpagesize);
+        goto error;
     }
 
     if (kvm_enabled() && !kvm_has_sync_mmu()) {
@@ -1094,8 +1097,8 @@ static void *file_ram_alloc(RAMBlock *block,
     return area;
 
 error:
-    if (mem_prealloc) {
-        exit(1);
+    if (area && area != MAP_FAILED) {
+        munmap(area, memory);
     }
     return NULL;
 }
-- 
1.9.3