[PATCH v1 5/9] cputlb: ensure we re-fill the TLB if it has reset

["Alex Bennée" <alex.bennee@linaro.org>]

Any write to a device might cause a re-arrangement of memory
triggering a TLB flush and potential re-size of the TLB invalidating
previous entries. This would cause users of qemu_plugin_get_hwaddr()
to see the warning:

  invalid use of qemu_plugin_get_hwaddr

because of the failed tlb_lookup which should always succeed. We catch
this case by checking to see if the list of entries has been cleared
and if so triggering a re-fill.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 accel/tcg/cputlb.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index eb2cf9de5e6..b7d329f7155 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1091,6 +1091,20 @@ static void io_writex(CPUArchState *env, CPUIOTLBEntry *iotlbentry,
                                MMU_DATA_STORE, mmu_idx, iotlbentry->attrs, r,
                                retaddr);
     }
+
+    /*
+     * The memory_region_dispatch may have triggered a flush/resize
+     * so for plugins we need to ensure we have reset the tlb_entry
+     * so any later lookup is correct.
+     */
+#ifdef CONFIG_PLUGIN
+    if (env_tlb(env)->d[mmu_idx].n_used_entries == 0) {
+        int size = op & MO_SIZE;
+        tlb_fill(env_cpu(env), addr, size, MMU_DATA_STORE,
+                 mmu_idx, retaddr);
+    }
+#endif
+
     if (locked) {
         qemu_mutex_unlock_iothread();
     }
-- 
2.20.1