cputlb: ensure we save the IOTLB data in case of reset

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. To
prevent this we save the IOTLB data in case it is later needed by a
plugin doing a lookup.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200713200415.26214-7-alex.bennee@linaro.org>

2 files changed, 17 insertions, 0 deletions

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 5542577d2b..8f145733ce 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -259,6 +259,18 @@ struct CPUWatchpoint {
     QTAILQ_ENTRY(CPUWatchpoint) entry;
 };
 
+#ifdef CONFIG_PLUGIN
+/*
+ * For plugins we sometime need to save the resolved iotlb data before
+ * the memory regions get moved around  by io_writex.
+ */
+typedef struct SavedIOTLB {
+    hwaddr addr;
+    MemoryRegionSection *section;
+    hwaddr mr_offset;
+} SavedIOTLB;
+#endif
+
 struct KVMState;
 struct kvm_run;
 
@@ -417,7 +429,11 @@ struct CPUState {
 
     DECLARE_BITMAP(plugin_mask, QEMU_PLUGIN_EV_MAX);
 
+#ifdef CONFIG_PLUGIN
     GArray *plugin_mem_cbs;
+    /* saved iotlb data from io_writex */
+    SavedIOTLB saved_iotlb;
+#endif
 
     /* TODO Move common fields from CPUArchState here. */
     int cpu_index;
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index 15f5047bf1..427027a970 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -116,6 +116,7 @@ typedef struct QObject QObject;
 typedef struct QString QString;
 typedef struct RAMBlock RAMBlock;
 typedef struct Range Range;
+typedef struct SavedIOTLB SavedIOTLB;
 typedef struct SHPCDevice SHPCDevice;
 typedef struct SSIBus SSIBus;
 typedef struct VirtIODevice VirtIODevice;