smc->default_caps.caps[SPAPR_CAP_HPT_MAXPAGESIZE] = 16; /* 64kiB */
smc->default_caps.caps[SPAPR_CAP_NESTED_KVM_HV] = SPAPR_CAP_OFF;
smc->default_caps.caps[SPAPR_CAP_LARGE_DECREMENTER] = SPAPR_CAP_ON;
- smc->default_caps.caps[SPAPR_CAP_CCF_ASSIST] = SPAPR_CAP_OFF;
+ smc->default_caps.caps[SPAPR_CAP_CCF_ASSIST] = SPAPR_CAP_ON;
spapr_caps_add_properties(smc, &error_abort);
smc->irq = &spapr_irq_dual;
smc->dr_phb_enabled = true;
*/
static void spapr_machine_4_2_class_options(MachineClass *mc)
{
+ SpaprMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
+
spapr_machine_5_0_class_options(mc);
compat_props_add(mc->compat_props, hw_compat_4_2, hw_compat_4_2_len);
+ smc->default_caps.caps[SPAPR_CAP_CCF_ASSIST] = SPAPR_CAP_OFF;
}
DEFINE_SPAPR_MACHINE(4_2, "4.2", false);
uint8_t kvm_val = kvmppc_get_cap_count_cache_flush_assist();
if (tcg_enabled() && val) {
- /* TODO - for now only allow broken for TCG */
- error_setg(errp,
-"Requested count cache flush assist capability level not supported by tcg,"
- " try appending -machine cap-ccf-assist=off");
+ /* TCG doesn't implement anything here, but allow with a warning */
+ warn_report("TCG doesn't support requested feature, cap-ccf-assist=on");
} else if (kvm_enabled() && (val > kvm_val)) {
+ uint8_t kvm_ibs = kvmppc_get_cap_safe_indirect_branch();
+
+ if (kvm_ibs == SPAPR_CAP_FIXED_CCD) {
+ /*
+ * If we don't have CCF assist on the host, the assist
+ * instruction is a harmless no-op. It won't correctly
+ * implement the cache count flush *but* if we have
+ * count-cache-disabled in the host, that flush is
+ * unnnecessary. So, specifically allow this case. This
+ * allows us to have better performance on POWER9 DD2.3,
+ * while still working on POWER9 DD2.2 and POWER8 host
+ * cpus.
+ */
+ return;
+ }
error_setg(errp,
"Requested count cache flush assist capability level not supported by kvm,"
" try appending -machine cap-ccf-assist=off");