spapr: nested: Introduce cap-nested-papr for Nested PAPR API

Introduce a SPAPR capability cap-nested-papr which enables nested PAPR
API for nested guests. This new API is to enable support for KVM on PowerVM
and the support in Linux kernel has already merged upstream.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

3 files changed, 61 insertions, 3 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index aaf7378..99d3fcb 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2166,6 +2166,7 @@ static const VMStateDescription vmstate_spapr = {
         &vmstate_spapr_cap_fwnmi,
         &vmstate_spapr_fwnmi,
         &vmstate_spapr_cap_rpt_invalidate,
+        &vmstate_spapr_cap_nested_papr,
         NULL
     }
 };
@@ -4732,6 +4733,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     smc->default_caps.caps[SPAPR_CAP_IBS] = SPAPR_CAP_WORKAROUND;
     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_NESTED_PAPR] = SPAPR_CAP_OFF;
     smc->default_caps.caps[SPAPR_CAP_LARGE_DECREMENTER] = SPAPR_CAP_ON;
     smc->default_caps.caps[SPAPR_CAP_CCF_ASSIST] = SPAPR_CAP_ON;
     smc->default_caps.caps[SPAPR_CAP_FWNMI] = SPAPR_CAP_ON;
diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
index e889244..62abf1b 100644
--- a/hw/ppc/spapr_caps.c
+++ b/hw/ppc/spapr_caps.c
@@ -487,6 +487,50 @@ static void cap_nested_kvm_hv_apply(SpaprMachineState *spapr,
             error_append_hint(errp, "Try appending -machine cap-nested-hv=off "
                                     "or use threads=1 with -smp\n");
         }
+        if (spapr_nested_api(spapr) &&
+            spapr_nested_api(spapr) != NESTED_API_KVM_HV) {
+            error_setg(errp, "Nested-HV APIs are mutually exclusive");
+            error_append_hint(errp, "Please use either cap-nested-hv or "
+                                    "cap-nested-papr to proceed.\n");
+            return;
+        } else {
+            spapr->nested.api = NESTED_API_KVM_HV;
+        }
+    }
+}
+
+static void cap_nested_papr_apply(SpaprMachineState *spapr,
+                                    uint8_t val, Error **errp)
+{
+    ERRP_GUARD();
+    PowerPCCPU *cpu = POWERPC_CPU(first_cpu);
+    CPUPPCState *env = &cpu->env;
+
+    if (!val) {
+        /* capability disabled by default */
+        return;
+    }
+
+    if (tcg_enabled()) {
+        if (!(env->insns_flags2 & PPC2_ISA300)) {
+            error_setg(errp, "Nested-PAPR only supported on POWER9 and later");
+            error_append_hint(errp,
+                              "Try appending -machine cap-nested-papr=off\n");
+            return;
+        }
+        if (spapr_nested_api(spapr) &&
+            spapr_nested_api(spapr) != NESTED_API_PAPR) {
+            error_setg(errp, "Nested-HV APIs are mutually exclusive");
+            error_append_hint(errp, "Please use either cap-nested-hv or "
+                                    "cap-nested-papr to proceed.\n");
+            return;
+        } else {
+            spapr->nested.api = NESTED_API_PAPR;
+        }
+    } else if (kvm_enabled()) {
+        error_setg(errp, "KVM implementation does not support Nested-PAPR");
+        error_append_hint(errp,
+                          "Try appending -machine cap-nested-papr=off\n");
     }
 }
 
@@ -735,6 +779,15 @@ SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
         .type = "bool",
         .apply = cap_nested_kvm_hv_apply,
     },
+    [SPAPR_CAP_NESTED_PAPR] = {
+        .name = "nested-papr",
+        .description = "Allow Nested HV (PAPR API)",
+        .index = SPAPR_CAP_NESTED_PAPR,
+        .get = spapr_cap_get_bool,
+        .set = spapr_cap_set_bool,
+        .type = "bool",
+        .apply = cap_nested_papr_apply,
+    },
     [SPAPR_CAP_LARGE_DECREMENTER] = {
         .name = "large-decr",
         .description = "Allow Large Decrementer",
@@ -919,6 +972,7 @@ SPAPR_CAP_MIG_STATE(sbbc, SPAPR_CAP_SBBC);
 SPAPR_CAP_MIG_STATE(ibs, SPAPR_CAP_IBS);
 SPAPR_CAP_MIG_STATE(hpt_maxpagesize, SPAPR_CAP_HPT_MAXPAGESIZE);
 SPAPR_CAP_MIG_STATE(nested_kvm_hv, SPAPR_CAP_NESTED_KVM_HV);
+SPAPR_CAP_MIG_STATE(nested_papr, SPAPR_CAP_NESTED_PAPR);
 SPAPR_CAP_MIG_STATE(large_decr, SPAPR_CAP_LARGE_DECREMENTER);
 SPAPR_CAP_MIG_STATE(ccf_assist, SPAPR_CAP_CCF_ASSIST);
 SPAPR_CAP_MIG_STATE(fwnmi, SPAPR_CAP_FWNMI);
diff --git a/hw/ppc/spapr_nested.c b/hw/ppc/spapr_nested.c
index ce3490b..936659b 100644
--- a/hw/ppc/spapr_nested.c
+++ b/hw/ppc/spapr_nested.c
@@ -13,13 +13,15 @@
 void spapr_nested_reset(SpaprMachineState *spapr)
 {
     if (spapr_get_cap(spapr, SPAPR_CAP_NESTED_KVM_HV)) {
-        spapr->nested.api = NESTED_API_KVM_HV;
         spapr_unregister_nested_hv();
         spapr_register_nested_hv();
-    } else {
-        spapr->nested.api = 0;
+    } else if (spapr_get_cap(spapr, SPAPR_CAP_NESTED_PAPR)) {
         spapr->nested.capabilities_set = false;
+        spapr_unregister_nested_papr();
+        spapr_register_nested_papr();
         spapr_nested_gsb_init();
+    } else {
+        spapr->nested.api = 0;
     }
 }