[PULL,22/96] ppc/pnv: use class attribute to limit SMT threads for different machines

Commit Message

Nicholas Piggin July 25, 2024, 11:52 p.m. UTC

Use a class attribute to specify the number of SMT threads per core
permitted for different machines, 8 for powernv8 and 4 for powernv9/10.

Reviewed-by: Cédric Le Goater <[e-mail]>
Reviewed-by: Harsh Prateek Bora <[e-mail]>
Signed-off-by: Nicholas Piggin <[e-mail]>
---
 hw/ppc/pnv.c         | 12 +++++++++---
 include/hw/ppc/pnv.h |  1 +
 2 files changed, 10 insertions(+), 3 deletions(-)

Patch

diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 91ff1be21f..a84e0e0e30 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -899,6 +899,7 @@  static void pnv_init(MachineState *machine)
     PnvMachineState *pnv = PNV_MACHINE(machine);
     MachineClass *mc = MACHINE_GET_CLASS(machine);
     PnvMachineClass *pmc = PNV_MACHINE_GET_CLASS(machine);
+    int max_smt_threads = pmc->max_smt_threads;
     char *fw_filename;
     long fw_size;
     uint64_t chip_ram_start = 0;
@@ -997,17 +998,19 @@  static void pnv_init(MachineState *machine)
     pnv->num_chips =
         machine->smp.max_cpus / (machine->smp.cores * machine->smp.threads);
 
-    if (machine->smp.threads > 8) {
-        error_report("Cannot support more than 8 threads/core "
-                     "on a powernv machine");
+    if (machine->smp.threads > max_smt_threads) {
+        error_report("Cannot support more than %d threads/core "
+                     "on %s machine", max_smt_threads, mc->desc);
         exit(1);
     }
+
     if (!is_power_of_2(machine->smp.threads)) {
         error_report("Cannot support %d threads/core on a powernv"
                      "machine because it must be a power of 2",
                      machine->smp.threads);
         exit(1);
     }
+
     /*
      * TODO: should we decide on how many chips we can create based
      * on #cores and Venice vs. Murano vs. Naples chip type etc...,
@@ -2490,6 +2493,7 @@  static void pnv_machine_power8_class_init(ObjectClass *oc, void *data)
 
     pmc->compat = compat;
     pmc->compat_size = sizeof(compat);
+    pmc->max_smt_threads = 8;
 
     machine_class_allow_dynamic_sysbus_dev(mc, TYPE_PNV_PHB);
 }
@@ -2514,6 +2518,7 @@  static void pnv_machine_power9_class_init(ObjectClass *oc, void *data)
 
     pmc->compat = compat;
     pmc->compat_size = sizeof(compat);
+    pmc->max_smt_threads = 4;
     pmc->dt_power_mgt = pnv_dt_power_mgt;
 
     machine_class_allow_dynamic_sysbus_dev(mc, TYPE_PNV_PHB);
@@ -2538,6 +2543,7 @@  static void pnv_machine_p10_common_class_init(ObjectClass *oc, void *data)
 
     pmc->compat = compat;
     pmc->compat_size = sizeof(compat);
+    pmc->max_smt_threads = 4;
     pmc->dt_power_mgt = pnv_dt_power_mgt;
 
     xfc->match_nvt = pnv10_xive_match_nvt;
diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
index 476b136146..1993dededf 100644
--- a/include/hw/ppc/pnv.h
+++ b/include/hw/ppc/pnv.h
@@ -76,6 +76,7 @@  struct PnvMachineClass {
     /*< public >*/
     const char *compat;
     int compat_size;
+    int max_smt_threads;
 
     void (*dt_power_mgt)(PnvMachineState *pnv, void *fdt);
     void (*i2c_init)(PnvMachineState *pnv);