diff mbox series

[PULL,08/60] memory-device: turn alignment assert into check

Message ID 1530216310-52873-9-git-send-email-pbonzini@redhat.com
State New
Headers show
Series [PULL,01/60] exec: Fix MAP_RAM for cached access | expand

Commit Message

Paolo Bonzini June 28, 2018, 8:04 p.m. UTC 
From: David Hildenbrand <david@redhat.com>

The start of the address space indicates which maximum alignment is
supported by our machine (e.g. ppc, x86 1GB). This is helpful to
catch fragmenting guest physical memory in strange fashions.

Right now we can crash QEMU by e.g. (there might be easier examples)

qemu-system-x86_64 -m 256M,maxmem=20G,slots=2 \
 -object memory-backend-file,id=mem0,size=8192M,mem-path=/dev/zero,align=8192M \
 -device pc-dimm,id=dimm1,memdev=mem0

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180607154705.6316-2-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/mem/memory-device.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index 3e04f39..6de4f70 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -116,9 +116,15 @@  uint64_t memory_device_get_free_addr(MachineState *ms, const uint64_t *hint,
     address_space_start = ms->device_memory->base;
     address_space_end = address_space_start +
                         memory_region_size(&ms->device_memory->mr);
-    g_assert(QEMU_ALIGN_UP(address_space_start, align) == address_space_start);
     g_assert(address_space_end >= address_space_start);
 
+    /* address_space_start indicates the maximum alignment we expect */
+    if (QEMU_ALIGN_UP(address_space_start, align) != address_space_start) {
+        error_setg(errp, "the alignment (0%" PRIx64 ") is not supported",
+                   align);
+        return 0;
+    }
+
     memory_device_check_addable(ms, size, errp);
     if (*errp) {
         return 0;