[Qemu-devel] [RFC][PATCH 10/16] memory: Introduce memory_region_init_reservation

[Jan Kiszka]

From: Jan Kiszka <address@hidden>

Introduce a memory region type that can reserve I/O space. Such regions
are useful for modeling I/O that is only handled outside of QEMU, i.e.
in the context of an accelerator like KVM. Any access to such a region
from QEMU is a bug and will be reported as such.

Signed-off-by: Jan Kiszka <address@hidden>
---
 memory.c |   35 +++++++++++++++++++++++++++++++++++
 memory.h |   15 +++++++++++++++
 2 files changed, 50 insertions(+), 0 deletions(-)

diff --git a/memory.c b/memory.c
index dc5e35d..a40990c 100644
--- a/memory.c
+++ b/memory.c
@@ -1003,6 +1003,41 @@ void memory_region_init_rom_device(MemoryRegion *mr,
     mr->backend_registered = true;
 }
 
+static uint64_t invalid_read(void *opaque, target_phys_addr_t addr,
+                             unsigned size)
+{
+    MemoryRegion *mr = opaque;
+
+    fprintf(stderr, "Invalid read from memory region %s\n", mr->name);
+    abort();
+}
+
+static void invalid_write(void *opaque, target_phys_addr_t addr, uint64_t data,
+                          unsigned size)
+{
+    MemoryRegion *mr = opaque;
+
+    fprintf(stderr, "Invalid write to memory region %s\n", mr->name);
+    abort();
+}
+
+static const MemoryRegionOps reservation_ops = {
+    .read = invalid_read,
+    .write = invalid_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+};
+
+void memory_region_init_reservation(MemoryRegion *mr,
+                                    const char *name,
+                                    uint64_t size)
+{
+    memory_region_init(mr, name, size);
+    mr->ops = &reservation_ops;
+    mr->opaque = mr;
+    mr->terminates = true;
+    mr->backend_registered = false;
+}
+
 void memory_region_destroy(MemoryRegion *mr)
 {
     assert(QTAILQ_EMPTY(&mr->subregions));
diff --git a/memory.h b/memory.h
index d5b47da..4ff441f 100644
--- a/memory.h
+++ b/memory.h
@@ -242,6 +242,21 @@ void memory_region_init_rom_device(MemoryRegion *mr,
                                    uint64_t size);
 
 /**
+ * memory_region_init_reservation: Initialize a memory region that reserves
+ *                                 I/O space.
+ *
+ * A reservation region primariy serves debugging purposes.  It claims I/O
+ * space that is not supposed to be handled by QEMU itself.  Any access via
+ * the memory API will cause an abort().
+ *
+ * @mr: the #MemoryRegion to be initialized
+ * @name: used for debugging; not visible to the user or ABI
+ * @size: size of the region.
+ */
+void memory_region_init_reservation(MemoryRegion *mr,
+                                    const char *name,
+                                    uint64_t size);
+/**
  * memory_region_destroy: Destroy a memory region and relaim all resources.
  *
  * @mr: the region to be destroyed.  May not currently be a subregion
-- 
1.7.3.4