[PATCH v2 3/6] spapr/xive: Add a warning when StoreEOI is activated on POWER9 CPUs

[Cédric Le Goater]

StoreEOI on POWER9 CPUs is racy because load-after-store ordering is
not enforced.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 hw/ppc/spapr_caps.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
index b0a9d0227db2..9251badbdc27 100644
--- a/hw/ppc/spapr_caps.c
+++ b/hw/ppc/spapr_caps.c
@@ -549,6 +549,15 @@ static void cap_storeeoi_apply(SpaprMachineState *spapr, 
uint8_t val,
             error_setg(errp, "StoreEOI not supported by KVM");
             return;
         }
+
+        /*
+         * load-after-store ordering is not enforced on POWER9 CPUs
+         * and StoreEOI can be racy.
+         */
+        if (!ppc_type_check_compat(machine->cpu_type, CPU_POWERPC_LOGICAL_3_10,
+                                  0, spapr->max_compat_pvr)) {
+            warn_report("StoreEOI on a POWER9 CPU is unsafe on KVM.");
+        }
     }
 }
 
-- 
2.25.4