Re: [PATCH 3/3] intel-iommu: build iova tree during IOMMU translation

[Peter Xu <peterx@redhat.com>]

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Jason,

On Mon, Dec 05, 2022 at 12:12:04PM +0800, Jason Wang wrote:
> I'm fine to go without iova-tree. Would you mind to post patches for
> fix? I can test and include it in this series then.

One sample patch attached, only compile tested.

I can also work on this but I'll be slow in making progress, so I'll add it
into my todo.  If you can help to fix this issue it'll be more than great.
No worry on the ownership or authorship of the patch if you agree on the
change and moving forward with this when modifying - just take it over!

Thanks!

-- 
Peter Xu

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From 57e5cab805c94d56f801a7e21098389a77584e34 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Mon, 5 Dec 2022 11:14:02 -0500
Subject: [PATCH] memory: sanity check flatview deref on mr transactions
Content-type: text/plain

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/exec/memory.h | 9 +++++++++
 softmmu/memory.c      | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 91f8a2395a..e136ab9558 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1069,8 +1069,17 @@ struct FlatView {
     MemoryRegion *root;
 };
 
+extern unsigned memory_region_transaction_depth;
+
 static inline FlatView *address_space_to_flatview(AddressSpace *as)
 {
+    /*
+     * Before using any flatview, sanity check we're not during a memory
+     * region transaction or the map can be invalid.  Note that this can
+     * also be called during commit phase of memory transaction, but that
+     * should also only happen when the depth decreases to 0 first.
+     */
+    assert(memory_region_transaction_depth == 0);
     return qatomic_rcu_read(&as->current_map);
 }
 
diff --git a/softmmu/memory.c b/softmmu/memory.c
index bc0be3f62c..7cfcf5dffe 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -37,7 +37,7 @@
 
 //#define DEBUG_UNASSIGNED
 
-static unsigned memory_region_transaction_depth;
+unsigned memory_region_transaction_depth;
 static bool memory_region_update_pending;
 static bool ioeventfd_update_pending;
 unsigned int global_dirty_tracking;
-- 
2.37.3