Commit 99605175c (xen-pt: Fix PCI devices re-attach failed) introduced
a subtle bug. As soon as the guest switches off Bus Mastering on the
device it immediately causes all the BARs be unmapped due to the DMA
address space of the device being changed. This is undesired behavior
because the guest may try to communicate with the device after that
which triggers the following errors in the logs:

[00:05.0] xen_pt_bar_read: Error: Should not read BAR through QEMU. 
[00:05.0] xen_pt_bar_write: Error: Should not write BAR through QEMU. 

The issue that the original patch tried to workaround (uneven number of
region_add/del calls on device attach/detach) was fixed in later QEMU

Signed-off-by: Igor Druzhinin <>
Reported-by: Ross Lagerwall <>
 hw/xen/xen_pt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index 9b7a960..e5a6eff 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -907,7 +907,7 @@ out:
-    memory_listener_register(&s->memory_listener, &s->dev.bus_master_as);
+    memory_listener_register(&s->memory_listener, &address_space_memory);
     memory_listener_register(&s->io_listener, &address_space_io);
     s->listener_set = true;

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