[Qemu-devel] [PATCH v9 1/6] hw/ppc/spapr.c: adding pending_dimm_unplugs to sPAPRMachineState

[Daniel Henrique Barboza]

The LMB DRC release callback, spapr_lmb_release(), uses an opaque
parameter, a sPAPRDIMMState struct that stores the current LMBs that
are allocated to a DIMM (nr_lmbs). After each call to this callback,
the nr_lmbs is decremented by one and, when it reaches zero, the callback
proceeds with the qdev calls to hot unplug the LMB.

Using drc->detach_cb_opaque is problematic because it can't be migrated in
the future DRC migration work. This patch makes the following changes to
eliminate the usage of this opaque callback inside spapr_lmb_release:

- sPAPRDIMMState was moved from spapr.c and added to spapr.h. A new
attribute called 'addr' was added to it. This is used as an unique
identifier to associate a sPAPRDIMMState to a PCDIMM element.

- sPAPRMachineState now hosts a new QTAILQ called 'pending_dimm_unplugs'.
This queue of sPAPRDIMMState elements will store the DIMM state of DIMMs
that are currently going under an unplug process.

- spapr_lmb_release() will now retrieve the nr_lmbs value by getting the
correspondent sPAPRDIMMState. A helper function called spapr_dimm_get_address
was created to fetch the address of a PCDIMM device inside spapr_lmb_release.
When nr_lmbs reaches zero and the callback proceeds with the qdev hot unplug
calls, the sPAPRDIMMState struct is removed from spapr->pending_dimm_unplugs.

After these changes, the opaque argument for spapr_lmb_release is now
unused and is passed as NULL inside spapr_del_lmbs. This and the other
opaque arguments can now be safely removed from the code.

Signed-off-by: Daniel Henrique Barboza <address@hidden>
---
 hw/ppc/spapr.c         | 54 ++++++++++++++++++++++++++++++++++++++++++++------
 include/hw/ppc/spapr.h | 17 ++++++++++++++++
 2 files changed, 65 insertions(+), 6 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 80d12d0..346c827 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2043,6 +2043,7 @@ static void ppc_spapr_init(MachineState *machine)
     msi_nonbroken = true;
 
     QLIST_INIT(&spapr->phbs);
+    QTAILQ_INIT(&spapr->pending_dimm_unplugs);
 
     /* Allocate RMA if necessary */
     rma_alloc_size = kvmppc_alloc_rma(&rma);
@@ -2596,20 +2597,32 @@ out:
     error_propagate(errp, local_err);
 }
 
-typedef struct sPAPRDIMMState {
-    uint32_t nr_lmbs;
-} sPAPRDIMMState;
+static uint64_t spapr_dimm_get_address(PCDIMMDevice *dimm)
+{
+    Error *local_err = NULL;
+    uint64_t addr;
+    addr = object_property_get_int(OBJECT(dimm), PC_DIMM_ADDR_PROP,
+                                   &local_err);
+    if (local_err) {
+        error_propagate(&error_abort, local_err);
+        return 0;
+    }
+    return addr;
+}
 
 static void spapr_lmb_release(DeviceState *dev, void *opaque)
 {
-    sPAPRDIMMState *ds = (sPAPRDIMMState *)opaque;
     HotplugHandler *hotplug_ctrl;
 
+    uint64_t addr = spapr_dimm_get_address(PC_DIMM(dev));
+    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
+    sPAPRDIMMState *ds = spapr_pending_dimm_unplugs_find(spapr, addr);
+
     if (--ds->nr_lmbs) {
         return;
     }
 
-    g_free(ds);
+    spapr_pending_dimm_unplugs_remove(spapr, ds);
 
     /*
      * Now that all the LMBs have been removed by the guest, call the
@@ -2626,17 +2639,20 @@ static void spapr_del_lmbs(DeviceState *dev, uint64_t 
addr_start, uint64_t size,
     sPAPRDRConnectorClass *drck;
     uint32_t nr_lmbs = size / SPAPR_MEMORY_BLOCK_SIZE;
     int i;
+    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
     sPAPRDIMMState *ds = g_malloc0(sizeof(sPAPRDIMMState));
     uint64_t addr = addr_start;
 
     ds->nr_lmbs = nr_lmbs;
+    ds->addr = addr_start;
+    spapr_pending_dimm_unplugs_add(spapr, ds);
     for (i = 0; i < nr_lmbs; i++) {
         drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
                 addr / SPAPR_MEMORY_BLOCK_SIZE);
         g_assert(drc);
 
         drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
-        drck->detach(drc, dev, spapr_lmb_release, ds, errp);
+        drck->detach(drc, dev, spapr_lmb_release, NULL, errp);
         addr += SPAPR_MEMORY_BLOCK_SIZE;
     }
 
@@ -3515,3 +3531,29 @@ static void spapr_machine_register_types(void)
 }
 
 type_init(spapr_machine_register_types)
+
+sPAPRDIMMState *spapr_pending_dimm_unplugs_find(sPAPRMachineState *spapr,
+                                                uint64_t addr)
+{
+    sPAPRDIMMState *dimm_state = NULL;
+    QTAILQ_FOREACH(dimm_state, &spapr->pending_dimm_unplugs, next) {
+        if (dimm_state->addr == addr) {
+            break;
+        }
+    }
+    return dimm_state;
+}
+
+void spapr_pending_dimm_unplugs_add(sPAPRMachineState *spapr,
+                                   sPAPRDIMMState *dimm_state)
+{
+    g_assert(!spapr_pending_dimm_unplugs_find(spapr, dimm_state->addr));
+    QTAILQ_INSERT_HEAD(&spapr->pending_dimm_unplugs, dimm_state, next);
+}
+
+void spapr_pending_dimm_unplugs_remove(sPAPRMachineState *spapr,
+                                      sPAPRDIMMState *dimm_state)
+{
+    QTAILQ_REMOVE(&spapr->pending_dimm_unplugs, dimm_state, next);
+    g_free(dimm_state);
+}
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 5802f88..3e2b5ab 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -32,6 +32,7 @@ struct sPAPRRTCState {
     int64_t ns_offset;
 };
 
+typedef struct sPAPRDIMMState sPAPRDIMMState;
 typedef struct sPAPRMachineClass sPAPRMachineClass;
 
 #define TYPE_SPAPR_MACHINE      "spapr-machine"
@@ -104,6 +105,9 @@ struct sPAPRMachineState {
     /* RTAS state */
     QTAILQ_HEAD(, sPAPRConfigureConnectorState) ccs_list;
 
+    /* pending DIMM unplug queue */
+    QTAILQ_HEAD(, sPAPRDIMMState) pending_dimm_unplugs;
+
     /*< public >*/
     char *kvm_type;
     MemoryHotplugState hotplug_memory;
@@ -646,6 +650,19 @@ struct sPAPRConfigureConnectorState {
 
 void spapr_ccs_reset_hook(void *opaque);
 
+struct sPAPRDIMMState {
+    uint64_t addr;
+    uint32_t nr_lmbs;
+    QTAILQ_ENTRY(sPAPRDIMMState) next;
+};
+
+sPAPRDIMMState *spapr_pending_dimm_unplugs_find(sPAPRMachineState *spapr,
+                                               uint64_t addr);
+void spapr_pending_dimm_unplugs_add(sPAPRMachineState *spapr,
+                                   sPAPRDIMMState *dimm_state);
+void spapr_pending_dimm_unplugs_remove(sPAPRMachineState *spapr,
+                                      sPAPRDIMMState *dimm_state);
+
 void spapr_rtc_read(sPAPRRTCState *rtc, struct tm *tm, uint32_t *ns);
 int spapr_rtc_import_offset(sPAPRRTCState *rtc, int64_t legacy_offset);
 
-- 
2.9.3