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[PATCH v6 4/5] memory: Add sanity check in address_space_to_flatview
From: |
Chuang Xu |
Subject: |
[PATCH v6 4/5] memory: Add sanity check in address_space_to_flatview |
Date: |
Fri, 3 Mar 2023 18:39:34 +0800 |
Before using any flatview, sanity check whether BQL or rcu is held. And
if we're during a memory region transaction, try to immediately update
mappings, or the map can be invalid.
Signed-off-by: Chuang Xu <xuchuangxclwt@bytedance.com>
---
include/exec/memory.h | 23 +++++++++++++++++++++++
softmmu/memory.c | 5 +++++
2 files changed, 28 insertions(+)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 2e602a2fad..84b531c6ff 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -27,6 +27,7 @@
#include "qemu/notify.h"
#include "qom/object.h"
#include "qemu/rcu.h"
+#include "qemu/main-loop.h"
#define RAM_ADDR_INVALID (~(ram_addr_t)0)
@@ -1095,8 +1096,30 @@ struct FlatView {
MemoryRegion *root;
};
+bool memory_region_transaction_in_progress(void);
+
+void memory_region_transaction_do_commit(void);
+
static inline FlatView *address_space_to_flatview(AddressSpace *as)
{
+ if (qemu_mutex_iothread_locked()) {
+ /* We exclusively own the flatview now.. */
+ if (memory_region_transaction_in_progress()) {
+ /*
+ * Fetch the flatview within a transaction in-progress, it
+ * means current_map may not be the latest, we need to update
+ * immediately to make sure the caller won't see obsolete
+ * mapping.
+ */
+ memory_region_transaction_do_commit();
+ }
+
+ /* No further protection needed to access current_map */
+ return as->current_map;
+ }
+
+ /* Otherwise we must have had the RCU lock or something went wrong */
+ assert(rcu_read_is_locked());
return qatomic_rcu_read(&as->current_map);
}
diff --git a/softmmu/memory.c b/softmmu/memory.c
index b89abf400e..1834e14cc8 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -1130,6 +1130,11 @@ void memory_region_transaction_commit(void)
}
}
+bool memory_region_transaction_in_progress(void)
+{
+ return memory_region_transaction_depth != 0;
+}
+
static void memory_region_destructor_none(MemoryRegion *mr)
{
}
--
2.20.1