spapr_drc: Prevent detach racing against attach for CPU DR

If a CPU is hot removed while hotplug of the same is still in progress,
the guest crashes. Prevent this by ensuring that detach is done only
after attach has completed.

The existing code already prevents such race for PCI hotplug. However
given that CPU is a logical DR unlike PCI and starts with ISOLATED
state, we need a logic that works for CPU too.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
               [Don't set awaiting_attach for PCI devices]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 94c875d75201e164a95d375fa3c5d66f37ebcccd..d276db3a726378dff9ebcca0ee3089fd30f92359 100644 (file)
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -140,6 +140,8 @@ static uint32_t set_allocation_state(sPAPRDRConnector *drc,
             DPRINTFN("finalizing device removal");
             drck->detach(drc, DEVICE(drc->dev), drc->detach_cb,
                          drc->detach_cb_opaque, NULL);
+        } else if (drc->allocation_state == SPAPR_DR_ALLOCATION_STATE_USABLE) {
+            drc->awaiting_allocation = false;
         }
     }
     return RTAS_OUT_SUCCESS;
@@ -373,6 +375,10 @@ static void attach(sPAPRDRConnector *drc, DeviceState *d, void *fdt,
     drc->signalled = (drc->type != SPAPR_DR_CONNECTOR_TYPE_PCI)
                      ? true : coldplug;
 
+    if (drc->type != SPAPR_DR_CONNECTOR_TYPE_PCI) {
+        drc->awaiting_allocation = true;
+    }
+
     object_property_add_link(OBJECT(drc), "device",
                              object_get_typename(OBJECT(drc->dev)),
                              (Object **)(&drc->dev),
@@ -421,6 +427,12 @@ static void detach(sPAPRDRConnector *drc, DeviceState *d,
         return;
     }
 
+    if (drc->awaiting_allocation) {
+        drc->awaiting_release = true;
+        DPRINTFN("awaiting allocation to complete before removal");
+        return;
+    }
+
     drc->indicator_state = SPAPR_DR_INDICATOR_STATE_INACTIVE;
 
     if (drc->detach_cb) {

diff --git a/include/hw/ppc/spapr_drc.h b/include/hw/ppc/spapr_drc.h
index fa21ba044438997b4e34aa4c55f761928e45a0fa..08e84114633c05efae53750a2b36493f55510f89 100644 (file)
--- a/include/hw/ppc/spapr_drc.h
+++ b/include/hw/ppc/spapr_drc.h
@@ -152,6 +152,7 @@ typedef struct sPAPRDRConnector {
 
     bool awaiting_release;
     bool signalled;
+    bool awaiting_allocation;
 
     /* device pointer, via link property */
     DeviceState *dev;