[PATCH 4/8] spapr/xive: Activate StoreEOI for POWER10 only

[Cédric Le Goater]

The StoreEOI features is safe to use with a P10 compat machine but not
with P9 compat, as it can not be migrated to a P9 host.

Introdude a "hw-storeeoi" property in the SpaprXive model to check for
the availability of StoreEOI at the HW level when a kernel IRQ chip is
in use. XIVE emulated is not impacted.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 include/hw/ppc/spapr_xive.h |  1 +
 hw/intc/spapr_xive.c        |  3 ++-
 hw/ppc/spapr_irq.c          | 20 ++++++++++++++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
index 3f325723ea74..402e38a7cf5e 100644
--- a/include/hw/ppc/spapr_xive.h
+++ b/include/hw/ppc/spapr_xive.h
@@ -51,6 +51,7 @@ typedef struct SpaprXive {
     VMChangeStateEntry *change;
 
     uint8_t       hv_prio;
+    bool          hw_storeeoi;
 } SpaprXive;
 
 typedef struct SpaprXiveClass {
diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
index 943b9958a68b..d184d17e30e7 100644
--- a/hw/intc/spapr_xive.c
+++ b/hw/intc/spapr_xive.c
@@ -596,6 +596,7 @@ static Property spapr_xive_properties[] = {
     DEFINE_PROP_UINT64("vc-base", SpaprXive, vc_base, SPAPR_XIVE_VC_BASE),
     DEFINE_PROP_UINT64("tm-base", SpaprXive, tm_base, SPAPR_XIVE_TM_BASE),
     DEFINE_PROP_UINT8("hv-prio", SpaprXive, hv_prio, 7),
+    DEFINE_PROP_BOOL("hw-storeeoi", SpaprXive, hw_storeeoi, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -945,7 +946,7 @@ static target_ulong h_int_get_source_info(PowerPCCPU *cpu,
         /*
          * Override QEMU settings with KVM values
          */
-        if (flags & XIVE_SRC_STORE_EOI) {
+        if (xive->hw_storeeoi && flags & XIVE_SRC_STORE_EOI) {
             args[0] |= SPAPR_XIVE_SRC_STORE_EOI;
         } else {
             args[0] &= ~SPAPR_XIVE_SRC_STORE_EOI;
diff --git a/hw/ppc/spapr_irq.c b/hw/ppc/spapr_irq.c
index 72bb938375ef..80cf1c3d6bb2 100644
--- a/hw/ppc/spapr_irq.c
+++ b/hw/ppc/spapr_irq.c
@@ -199,6 +199,23 @@ static int spapr_irq_check(SpaprMachineState *spapr, Error 
**errp)
     return 0;
 }
 
+static bool spapr_irq_xive_hw_storeeoi(SpaprMachineState *spapr)
+{
+    MachineState *machine = MACHINE(spapr);
+
+    /*
+     * All P10 compat kernels should enforce load-after-store ordering
+     * for StoreEOI.
+     */
+    if (ppc_type_check_compat(machine->cpu_type, CPU_POWERPC_LOGICAL_3_10,
+                              0, spapr->max_compat_pvr)) {
+        return true;
+    }
+
+    /* StoreEOI on P9 compat is unsafe */
+    return false;
+}
+
 /*
  * sPAPR IRQ frontend routines for devices
  */
@@ -325,6 +342,7 @@ void spapr_irq_init(SpaprMachineState *spapr, Error **errp)
 
     if (spapr->irq->xive) {
         uint32_t nr_servers = spapr_max_server_number(spapr);
+        bool storeeoi = spapr_irq_xive_hw_storeeoi(spapr);
         DeviceState *dev;
         int i;
 
@@ -337,6 +355,8 @@ void spapr_irq_init(SpaprMachineState *spapr, Error **errp)
         qdev_prop_set_uint32(dev, "nr-ends", nr_servers << 3);
         object_property_set_link(OBJECT(dev), "xive-fabric", OBJECT(spapr),
                                  &error_abort);
+        object_property_set_bool(OBJECT(dev), "hw-storeeoi", storeeoi,
+                                 &error_abort);
         sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
 
         spapr->xive = SPAPR_XIVE(dev);
-- 
2.25.4