[Qemu-devel] [PATCHv3] qxl: error handling fixes and cleanups.

[Alon Levy <alevy@redhat.com>]

From: Gerd Hoffmann <kraxel@redhat.com>

Add qxl_guest_bug() function which is supposed to be called in case
sanity checks of guest requests fail.  It raises an error IRQ and
logs a message in case guest debugging is enabled.

Make PANIC_ON() abort instead of exit.  That macro should be used
for qemu bugs only, any guest-triggerable stuff should use the new
qxl_guest_bug() function instead.

Convert a few easy cases from PANIC_ON() to qxl_guest_bug() to
show intended usage.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/qxl.c |   32 ++++++++++++++++++++++++++++----
 hw/qxl.h |    3 ++-
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/hw/qxl.c b/hw/qxl.c
index 7be7ae1..91bc98d 100644
--- a/hw/qxl.c
+++ b/hw/qxl.c
@@ -124,6 +124,14 @@ static void qxl_reset_memslots(PCIQXLDevice *d);
 static void qxl_reset_surfaces(PCIQXLDevice *d);
 static void qxl_ring_set_dirty(PCIQXLDevice *qxl);
 
+void qxl_guest_bug(PCIQXLDevice *qxl, const char *msg)
+{
+    qxl_send_events(qxl, QXL_INTERRUPT_ERROR);
+    if (qxl->guestdebug) {
+        fprintf(stderr, "qxl-%d: guest bug: %s\n", qxl->id, msg);
+    }
+}
+
 
 void qxl_spice_update_area(PCIQXLDevice *qxl, uint32_t surface_id,
                            struct QXLRect *area, struct QXLRect *dirty_rects,
@@ -1111,22 +1119,38 @@ static void ioport_write(void *opaque, uint32_t addr, uint32_t val)
         qxl_hard_reset(d, 0);
         break;
     case QXL_IO_MEMSLOT_ADD:
-        PANIC_ON(val >= NUM_MEMSLOTS);
-        PANIC_ON(d->guest_slots[val].active);
+        if (val >= NUM_MEMSLOTS) {
+            qxl_guest_bug(d, "QXL_IO_MEMSLOT_ADD: val out of range");
+            break;
+        }
+        if (d->guest_slots[val].active) {
+            qxl_guest_bug(d, "QXL_IO_MEMSLOT_ADD: memory slot already active");
+            break;
+        }
         d->guest_slots[val].slot = d->ram->mem_slot;
         qxl_add_memslot(d, val, 0);
         break;
     case QXL_IO_MEMSLOT_DEL:
+        if (val >= NUM_MEMSLOTS) {
+            qxl_guest_bug(d, "QXL_IO_MEMSLOT_DEL: val out of range");
+            break;
+        }
         qxl_del_memslot(d, val);
         break;
     case QXL_IO_CREATE_PRIMARY:
-        PANIC_ON(val != 0);
+        if (val != 0) {
+            qxl_guest_bug(d, "QXL_IO_CREATE_PRIMARY: val != 0");
+            break;
+        }
         dprint(d, 1, "QXL_IO_CREATE_PRIMARY\n");
         d->guest_primary.surface = d->ram->create_surface;
         qxl_create_guest_primary(d, 0);
         break;
     case QXL_IO_DESTROY_PRIMARY:
-        PANIC_ON(val != 0);
+        if (val != 0) {
+            qxl_guest_bug(d, "QXL_IO_DESTROY_PRIMARY: val != 0");
+            break;
+        }
         dprint(d, 1, "QXL_IO_DESTROY_PRIMARY (%s)\n", qxl_mode_to_string(d->mode));
         if (d->mode != QXL_MODE_UNDEFINED) {
             d->mode = QXL_MODE_UNDEFINED;
diff --git a/hw/qxl.h b/hw/qxl.h
index 087ef6b..88393c2 100644
--- a/hw/qxl.h
+++ b/hw/qxl.h
@@ -86,7 +86,7 @@ typedef struct PCIQXLDevice {
 
 #define PANIC_ON(x) if ((x)) {                         \
     printf("%s: PANIC %s failed\n", __FUNCTION__, #x); \
-    exit(-1);                                          \
+    abort();                                           \
 }
 
 #define dprint(_qxl, _level, _fmt, ...)                                 \
@@ -99,6 +99,7 @@ typedef struct PCIQXLDevice {
 
 /* qxl.c */
 void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL phys, int group_id);
+void qxl_guest_bug(PCIQXLDevice *qxl, const char *msg);
 
 void qxl_spice_update_area(PCIQXLDevice *qxl, uint32_t surface_id,
                            struct QXLRect *area, struct QXLRect *dirty_rects,
-- 
1.7.6