[PATCH] accel/tcg: Call tcg_tb_insert() for one-insn TBs

[Ilya Leoshkevich]

Currently single-insn TBs created from I/O memory are not added to
region_trees. Therefore, when they generate exceptions, they are not
handled by cpu_restore_state_from_tb(). For x86 this is not a problem,
because x86_restore_state_to_opc() only restores pc and cc, which are
already correct. However, on several other architectures,
restore_state_to_opc() restores more registers, and guests can notice
incorrect values.

Fix by always calling tcg_tb_insert(). This may increase the size of
region_trees, but tcg_region_reset_all() clears it once code_gen_buffer
fills up, so it will not grow uncontrollably.

Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 accel/tcg/translate-all.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 453eb20ec95..6333302813e 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -531,23 +531,23 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
         tb_reset_jump(tb, 1);
     }
 
+    /*
+     * Insert TB into the corresponding region tree before publishing it
+     * through QHT. Otherwise rewinding happened in the TB might fail to
+     * lookup itself using host PC.
+     */
+    tcg_tb_insert(tb);
+
     /*
      * If the TB is not associated with a physical RAM page then it must be
      * a temporary one-insn TB, and we have nothing left to do. Return early
-     * before attempting to link to other TBs or add to the lookup table.
+     * before attempting to link to other TBs.
      */
     if (tb_page_addr0(tb) == -1) {
         assert_no_pages_locked();
         return tb;
     }
 
-    /*
-     * Insert TB into the corresponding region tree before publishing it
-     * through QHT. Otherwise rewinding happened in the TB might fail to
-     * lookup itself using host PC.
-     */
-    tcg_tb_insert(tb);
-
     /*
      * No explicit memory barrier is required -- tb_link_page() makes the
      * TB visible in a consistent state.
-- 
2.47.1