[PATCH 03/11] exec: add ram_debug_ops support

[Ashish Kalra <Ashish.Kalra@xxxxxxx>]

From: Brijesh Singh <brijesh.singh@xxxxxxx>

From: Brijesh Singh <brijesh.singh@xxxxxxx>

Currently, guest memory access for debugging purposes is performed using
memcpy(). Extend the 'struct MemoryRegion' to include new callbacks that
can be used to override the use of memcpy() with something else.

The new callbacks can be used to display the guest memory of an SEV guest
by registering callbacks to the SEV memory encryption/decryption APIs.

Typical usage:

mem_read(uint8_t *dst, uint8_t *src, uint32_t len, MemTxAttrs *attrs);
mem_write(uint8_t *dst, uint8_t *src, uint32_t len, MemTxAttrs *attrs);

MemoryRegionRAMReadWriteOps ops;
ops.read = mem_read;
ops.write = mem_write;

memory_region_init_ram(mem, NULL, "memory", size, NULL);
memory_region_set_ram_debug_ops(mem, ops);

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
---
 include/exec/memory.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 73deb4b456..2fb4193358 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -402,6 +402,18 @@ struct IOMMUMemoryRegionClass {
 typedef struct CoalescedMemoryRange CoalescedMemoryRange;
 typedef struct MemoryRegionIoeventfd MemoryRegionIoeventfd;
 
+/* Memory Region RAM debug callback */
+typedef struct MemoryRegionRAMReadWriteOps MemoryRegionRAMReadWriteOps;
+
+struct MemoryRegionRAMReadWriteOps {
+    /* Write data into guest memory */
+    int (*write) (uint8_t *dest, const uint8_t *src,
+                  uint32_t len, MemTxAttrs attrs);
+    /* Read data from guest memory */
+    int (*read) (uint8_t *dest, const uint8_t *src,
+                 uint32_t len, MemTxAttrs attrs);
+};
+
 /** MemoryRegion:
  *
  * A struct representing a memory region.
@@ -445,6 +457,7 @@ struct MemoryRegion {
     const char *name;
     unsigned ioeventfd_nb;
     MemoryRegionIoeventfd *ioeventfds;
+    const MemoryRegionRAMReadWriteOps *ram_debug_ops;
 };
 
 struct IOMMUMemoryRegion {
@@ -1060,6 +1073,20 @@ void memory_region_init_rom_nomigrate(MemoryRegion *mr,
                                       uint64_t size,
                                       Error **errp);
 
+/**
+ * memory_region_set_ram_debug_ops: Set access ops for a give memory region.
+ *
+ * @mr: the #MemoryRegion to be initialized
+ * @ops: a function that will be used when accessing @target region during
+ *       debug
+ */
+static inline void
+memory_region_set_ram_debug_ops(MemoryRegion *mr,
+                                const MemoryRegionRAMReadWriteOps *ops)
+{
+    mr->ram_debug_ops = ops;
+}
+
 /**
  * memory_region_init_rom_device_nomigrate:  Initialize a ROM memory region.
  *                                 Writes are handled via callbacks.
-- 
2.17.1