memory: Introduce memory_region_init_reservation
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, but could theoretically
be triggered by guest code (DMA to reserved region). So only warning
about such events once, then ignore them.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/memory.c b/memory.c
index 6201a37..68e5cdf 100644
--- a/memory.c
+++ b/memory.c
@@ -1049,6 +1049,42 @@
mr->ram_addr |= cpu_register_io_memory(mr);
}
+static uint64_t invalid_read(void *opaque, target_phys_addr_t addr,
+ unsigned size)
+{
+ MemoryRegion *mr = opaque;
+
+ if (!mr->warning_printed) {
+ fprintf(stderr, "Invalid read from memory region %s\n", mr->name);
+ mr->warning_printed = true;
+ }
+ return -1U;
+}
+
+static void invalid_write(void *opaque, target_phys_addr_t addr, uint64_t data,
+ unsigned size)
+{
+ MemoryRegion *mr = opaque;
+
+ if (!mr->warning_printed) {
+ fprintf(stderr, "Invalid write to memory region %s\n", mr->name);
+ mr->warning_printed = true;
+ }
+}
+
+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_io(mr, &reservation_ops, mr, name, size);
+}
+
void memory_region_destroy(MemoryRegion *mr)
{
assert(QTAILQ_EMPTY(&mr->subregions));