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[2/3] spapr: Detect hot unplugged devices during CAS

Message ID 158076937624.2118610.5063572290769102838.stgit@bahia.lan (mailing list archive)
State New, archived
Headers show
Series spapr: Fix device unplug vs CAS or migration | expand

Commit Message

Greg Kurz Feb. 3, 2020, 10:36 p.m. UTC 
We can't properly handle hotplug of a device as long the guest kernel isn't
fully booted. We detect this at CAS and potentially trigger a CAS reboot to
complete the hotplug sequence.

The same goes actually with hot unplug but we currently don't detect it.
Doing device_del before CAS hence seems to be ignored: when the guest
is booted, it still sees the _unplugged_ device in the DT and configures
it. But if some other hotplug event happens later, then the unplug request
is finally processed by the guest and the device goes away.

This doesn't seem to cause any crash but it is still very confusing. Detect
device unplug at CAS and request a CAS reboot.

Hopefully, when SLOF will know how to handle device addition and deletion
in its DT according to the FDT provided by QEMU at CAS, we'll be able to
address this differently (ie, coldplugging the new devices and removing the
ones with a pending unplug request).

Signed-off-by: Greg Kurz <groug@kaod.org>
---
 hw/ppc/spapr_hcall.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 7a33d79bbae9..84690cc2c1ce 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1659,7 +1659,7 @@  static bool spapr_hotplugged_dev_before_cas(void)
         if (!drc->dev) {
             continue;
         }
-        if (!spapr_drc_device_ready(drc)) {
+        if (spapr_drc_unplug_requested(drc) || !spapr_drc_device_ready(drc)) {
             return true;
         }
     }