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authorCornelia Huck <cohuck@redhat.com>2018-05-04 14:53:16 +0200
committerCornelia Huck <cohuck@redhat.com>2018-05-14 17:10:02 +0200
commit6e9c893ecd00afd5344c35d0d0ded50eaa0938f6 (patch)
tree89e06ff4476e533057867d8fd29929d1c8570093 /hw/s390x
parentbbd87423ea0c436c55bbc3f9c23d4f811d1f3f29 (diff)
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s390x/css: disabled subchannels cannot be status pending
The 3270 code will try to post an attention interrupt when the 3270 emulator (e.g. x3270) attaches. If the guest has not yet enabled the subchannel for the 3270 device, we will present a spurious cc 1 (status pending) when it uses msch on it later on, e.g. when trying to enable the subchannel. To fix this, just don't do anything in css_conditional_io_interrupt() if the subchannel is not enabled. The 3270 code will work fine with that, and the other user of this function (virtio-ccw) never attempts to post an interrupt for a disabled device to begin with. CC: qemu-stable@nongnu.org Reported-by: Thomas Huth <thuth@redhat.com> Tested-by: Thomas Huth <thuth@redhat.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Halil Pasic <pasic@linux.ibm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Diffstat (limited to 'hw/s390x')
-rw-r--r--hw/s390x/css.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 301bf17..56c3fa8 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -617,6 +617,14 @@ void css_inject_io_interrupt(SubchDev *sch)
void css_conditional_io_interrupt(SubchDev *sch)
{
/*
+ * If the subchannel is not enabled, it is not made status pending
+ * (see PoP p. 16-17, "Status Control").
+ */
+ if (!(sch->curr_status.pmcw.flags & PMCW_FLAGS_MASK_ENA)) {
+ return;
+ }
+
+ /*
* If the subchannel is not currently status pending, make it pending
* with alert status.
*/