[Qemu-devel] [PATCH v3 42/47] qemu_ram_block_from_host

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Postcopy sends RAMBlock names and offsets over the wire (since it can't
rely on the order of ramaddr being the same), and it starts out with
HVA fault addresses from the kernel.

qemu_ram_block_from_host translates a HVA into a RAMBlock, an offset
in the RAMBlock, the global ram_addr_t value and it's bitmap position.

Rewrite qemu_ram_addr_from_host to use qemu_ram_block_from_host.

Provide qemu_ram_get_idstr since it's the actual name text sent on the
wire.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 exec.c                    | 56 ++++++++++++++++++++++++++++++++++++++++++-----
 include/exec/cpu-common.h |  4 ++++
 2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/exec.c b/exec.c
index 8b95502..7c43485 100644
--- a/exec.c
+++ b/exec.c
@@ -1176,6 +1176,11 @@ static RAMBlock *find_ram_block(ram_addr_t addr)
     return NULL;
 }
 
+const char *qemu_ram_get_idstr(RAMBlock *rb)
+{
+    return rb->idstr;
+}
+
 void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev)
 {
     RAMBlock *new_block = find_ram_block(addr);
@@ -1515,16 +1520,35 @@ static void *qemu_ram_ptr_length(ram_addr_t addr, hwaddr *size)
     }
 }
 
-/* Some of the softmmu routines need to translate from a host pointer
-   (typically a TLB entry) back to a ram offset.  */
-MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
+/*
+ * Translates a host ptr back to a RAMBlock, a ram_addr and an offset
+ * in that RAMBlock.
+ *
+ * ptr: Host pointer to look up
+ * round_offset: If true round the result offset down to a page boundary
+ * *ram_addr: set to result ram_addr
+ * *offset: set to result offset within the RAMBlock
+ * *bm_index: bitmap index (i.e. scaled ram_addr for use where the scale
+ *                          isn't available)
+ *
+ * Returns: RAMBlock (or NULL if not found)
+ */
+RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
+                                   ram_addr_t *ram_addr,
+                                   ram_addr_t *offset,
+                                   unsigned long *bm_index)
 {
     RAMBlock *block;
     uint8_t *host = ptr;
 
     if (xen_enabled()) {
         *ram_addr = xen_ram_addr_from_mapcache(ptr);
-        return qemu_get_ram_block(*ram_addr)->mr;
+        block = qemu_get_ram_block(*ram_addr);
+        if (!block) {
+            return NULL;
+        }
+        *offset = (host - block->host);
+        return block;
     }
 
     block = ram_list.mru_block;
@@ -1545,7 +1569,29 @@ MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
     return NULL;
 
 found:
-    *ram_addr = block->offset + (host - block->host);
+    *offset = (host - block->host);
+    if (round_offset) {
+        *offset &= TARGET_PAGE_MASK;
+    }
+    *ram_addr = block->offset + *offset;
+    *bm_index = *ram_addr >> TARGET_PAGE_BITS;
+    return block;
+}
+
+/* Some of the softmmu routines need to translate from a host pointer
+   (typically a TLB entry) back to a ram offset.  */
+MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
+{
+    RAMBlock *block;
+    ram_addr_t offset; /* Not used */
+    unsigned long index; /* Not used */
+
+    block = qemu_ram_block_from_host(ptr, false, ram_addr, &offset, &index);
+
+    if (!block) {
+        return NULL;
+    }
+
     return block->mr;
 }
 
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 8042f50..ae25407 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -55,8 +55,12 @@ typedef uint32_t CPUReadMemoryFunc(void *opaque, hwaddr addr);
 void qemu_ram_remap(ram_addr_t addr, ram_addr_t length);
 /* This should not be used by devices.  */
 MemoryRegion *qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr);
+RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
+                                   ram_addr_t *ram_addr, ram_addr_t *offset,
+                                   unsigned long *bm_index);
 void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev);
 void qemu_ram_unset_idstr(ram_addr_t addr);
+const char *qemu_ram_get_idstr(RAMBlock *rb);
 
 void cpu_physical_memory_rw(hwaddr addr, uint8_t *buf,
                             int len, int is_write);
-- 
1.9.3