[Qemu-devel] [PATCH v5 09/16] spapr_events: event-scan RTAS interface

[Michael Roth <mdroth@linux.vnet.ibm.com>]

From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>

We don't actually rely on this interface to surface hotplug events, and
instead rely on the similar-but-interrupt-driven check-exception RTAS
interface used for EPOW events. However, the existence of this interface
is needed to ensure guest kernels initialize the event-reporting
interfaces which will in turn be used by userspace tools to handle these
events, so we implement this interface here.

Since events surfaced by this call are mutually exclusive to those
surfaced via check-exception, we also update the RTAS event queue code
to accept a boolean to mark/filter for events accordingly.

Events of this sort are not currently generated by QEMU, but the interface
has been tested by surfacing hotplug events via event-scan in place
of check-exception.

Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c         |  1 +
 hw/ppc/spapr_events.c  | 67 ++++++++++++++++++++++++++++++++++++++++++++++----
 include/hw/ppc/spapr.h |  2 ++
 3 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 861107e..4b7be72 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -541,6 +541,7 @@ static void *spapr_create_fdt_skel(hwaddr initrd_base,
         refpoints, sizeof(refpoints))));
 
     _FDT((fdt_property_cell(fdt, "rtas-error-log-max", RTAS_ERROR_LOG_MAX)));
+    _FDT((fdt_property_cell(fdt, "rtas-event-scan-rate", RTAS_EVENT_SCAN_RATE)));
 
     /*
      * According to PAPR, rtas ibm,os-term does not guarantee a return
diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index 0eeb1d8..867c8e0 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -238,6 +238,11 @@ void spapr_events_fdt_skel(void *fdt, uint32_t check_exception_irq)
 
 typedef struct EventLogEntry {
     int log_type;
+    /* according to PAPR+ 2.7, 10.1, events to be retrieved via
+     * check-exception are mutually exclusive with those to be
+     * retrieved via event-scan
+     */
+    bool exception;
     void *data;
     QTAILQ_ENTRY(EventLogEntry) next;
 } EventLogEntry;
@@ -246,16 +251,17 @@ static struct {
     QTAILQ_HEAD(, EventLogEntry) pending_events;
 } rtas_event_log;
 
-static void rtas_event_log_queue(int log_type, void *data)
+static void rtas_event_log_queue(int log_type, void *data, bool exception)
 {
     EventLogEntry *entry = g_new(EventLogEntry, 1);
 
     entry->log_type = log_type;
+    entry->exception = exception;
     entry->data = data;
     QTAILQ_INSERT_TAIL(&rtas_event_log.pending_events, entry, next);
 }
 
-static EventLogEntry *rtas_event_log_dequeue(uint32_t event_mask)
+static EventLogEntry *rtas_event_log_dequeue(uint32_t event_mask, bool exception)
 {
     EventLogEntry *entry = NULL;
 
@@ -265,6 +271,9 @@ static EventLogEntry *rtas_event_log_dequeue(uint32_t event_mask)
     }
 
     QTAILQ_FOREACH(entry, &rtas_event_log.pending_events, next) {
+        if (entry->exception != exception) {
+            continue;
+        }
         /* EPOW and hotplug events are surfaced in the same manner */
         if (entry->log_type == RTAS_LOG_TYPE_EPOW ||
             entry->log_type == RTAS_LOG_TYPE_HOTPLUG) {
@@ -356,7 +365,7 @@ static void spapr_powerdown_req(Notifier *n, void *opaque)
     epow->event_modifier = RTAS_LOG_V6_EPOW_MODIFIER_NORMAL;
     epow->extended_modifier = RTAS_LOG_V6_EPOW_XMODIFIER_PARTITION_SPECIFIC;
 
-    rtas_event_log_queue(RTAS_LOG_TYPE_EPOW, pending_epow);
+    rtas_event_log_queue(RTAS_LOG_TYPE_EPOW, pending_epow, true);
 
     qemu_irq_pulse(xics_get_qirq(spapr->icp, spapr->check_exception_irq));
 }
@@ -415,7 +424,7 @@ static void spapr_hotplug_req_event(sPAPRDRConnector *drc, uint8_t hp_action)
         return;
     }
 
-    rtas_event_log_queue(RTAS_LOG_TYPE_HOTPLUG, new_hp);
+    rtas_event_log_queue(RTAS_LOG_TYPE_HOTPLUG, new_hp, true);
 
     qemu_irq_pulse(xics_get_qirq(spapr->icp, spapr->check_exception_irq));
 }
@@ -452,7 +461,54 @@ static void check_exception(PowerPCCPU *cpu, sPAPREnvironment *spapr,
         xinfo |= (uint64_t)rtas_ld(args, 6) << 32;
     }
 
-    event = rtas_event_log_dequeue(mask);
+    event = rtas_event_log_dequeue(mask, true);
+    if (!event) {
+        goto out_no_events;
+    }
+
+    switch (event->log_type) {
+        case RTAS_LOG_TYPE_EPOW:
+            event_len = sizeof(struct epow_log_full);
+            break;
+        case RTAS_LOG_TYPE_HOTPLUG:
+            event_len = sizeof(struct hp_log_full);
+            break;
+        default:
+            goto out_no_events;
+    }
+
+    if (event_len < len) {
+        len = event_len;
+    }
+
+    cpu_physical_memory_write(buf, event->data, len);
+    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+    g_free(event->data);
+    g_free(event);
+    return;
+
+out_no_events:
+    rtas_st(rets, 0, RTAS_OUT_NO_ERRORS_FOUND);
+}
+
+static void event_scan(PowerPCCPU *cpu, sPAPREnvironment *spapr,
+                       uint32_t token, uint32_t nargs,
+                       target_ulong args,
+                       uint32_t nret, target_ulong rets)
+{
+    uint32_t mask, buf, len, event_len;
+    EventLogEntry *event;
+
+    if (nargs != 4 || nret != 1) {
+        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
+        return;
+    }
+
+    mask = rtas_ld(args, 0);
+    buf = rtas_ld(args, 2);
+    len = rtas_ld(args, 3);
+
+    event = rtas_event_log_dequeue(mask, false);
     if (!event) {
         goto out_no_events;
     }
@@ -490,4 +546,5 @@ void spapr_events_init(sPAPREnvironment *spapr)
     qemu_register_powerdown_notifier(&spapr->epow_notifier);
     spapr_rtas_register(RTAS_CHECK_EXCEPTION, "check-exception",
                         check_exception);
+    spapr_rtas_register(RTAS_EVENT_SCAN, "event-scan", event_scan);
 }
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 1d27708..8acf41a 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -465,6 +465,8 @@ int spapr_rtas_device_tree_setup(void *fdt, hwaddr rtas_addr,
 
 #define RTAS_ERROR_LOG_MAX      2048
 
+#define RTAS_EVENT_SCAN_RATE    1
+
 typedef struct sPAPRTCETable sPAPRTCETable;
 
 #define TYPE_SPAPR_TCE_TABLE "spapr-tce-table"
-- 
1.9.1