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[PATCH v3 03/10] exec: Fix for qemu_ram_resize() callback

From: Shameer Kolothum
Subject: [PATCH v3 03/10] exec: Fix for qemu_ram_resize() callback
Date: Wed, 11 Mar 2020 17:20:07 +0000

From: David Hildenbrand <address@hidden>

Summarizing the issue:
1. Memory regions contain ram blocks with a different size,  if the
   size is  not properly aligned. While memory regions can have an
   unaligned size, ram blocks can't. This is true when creating
   resizable memory region with  an unaligned size.
2. When resizing a ram block/memory region, the size of the memory
   region  is set to the aligned size. The callback is called with
   the aligned size. The unaligned piece is lost.

Because of the above, if ACPI blob length modifications happens
after the initial virt_acpi_build() call, and the changed blob
length is within the PAGE size boundary, then the revised size
is not seen by the firmware on Guest reboot.

Hence make sure callback is called if memory region size is changed,
irrespective of aligned or not.

Signed-off-by: David Hildenbrand <address@hidden>
[Shameer: added commit log]
Signed-off-by: Shameer Kolothum <address@hidden>
Please find the discussion here,
 exec.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/exec.c b/exec.c
index 0cc500d53a..f8974cd303 100644
--- a/exec.c
+++ b/exec.c
@@ -2073,11 +2073,21 @@ static int memory_try_enable_merging(void *addr, size_t 
 int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, Error **errp)
+    const ram_addr_t unaligned_size = newsize;
     newsize = HOST_PAGE_ALIGN(newsize);
     if (block->used_length == newsize) {
+        /*
+         * We don't have to resize the ram block (which only knows aligned
+         * sizes), however, we have to notify if the unaligned size changed.
+         */
+        if (block->resized && unaligned_size != memory_region_size(block->mr)) 
+            block->resized(block->idstr, unaligned_size, block->host);
+            memory_region_set_size(block->mr, unaligned_size);
+        }
         return 0;
@@ -2101,9 +2111,9 @@ int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, 
Error **errp)
     block->used_length = newsize;
     cpu_physical_memory_set_dirty_range(block->offset, block->used_length,
-    memory_region_set_size(block->mr, newsize);
+    memory_region_set_size(block->mr, unaligned_size);
     if (block->resized) {
-        block->resized(block->idstr, newsize, block->host);
+        block->resized(block->idstr, unaligned_size, block->host);
     return 0;

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