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>

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;

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);

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;
     }
 }
 

include/hw/ppc/spapr.h

@@ -81,8 +81,10 @@ typedef enum {
 #define SPAPR_CAP_RPT_INVALIDATE        0x0B
 /* Support for AIL modes */
 #define SPAPR_CAP_AIL_MODE_3            0x0C
+/* Nested PAPR */
+#define SPAPR_CAP_NESTED_PAPR           0x0D
 /* Num Caps */
-#define SPAPR_CAP_NUM                   (SPAPR_CAP_AIL_MODE_3 + 1)
+#define SPAPR_CAP_NUM                   (SPAPR_CAP_NESTED_PAPR + 1)
 
 /*
  * Capability Values
@@ -592,6 +594,7 @@ struct SpaprMachineState {
 #define H_GUEST_CREATE_VCPU      0x474
 #define H_GUEST_GET_STATE        0x478
 #define H_GUEST_SET_STATE        0x47C
+#define H_GUEST_RUN_VCPU         0x480
 #define H_GUEST_DELETE           0x488
 
 #define MAX_HCALL_OPCODE         H_GUEST_DELETE
@@ -996,6 +999,7 @@ extern const VMStateDescription vmstate_spapr_cap_sbbc;
 extern const VMStateDescription vmstate_spapr_cap_ibs;
 extern const VMStateDescription vmstate_spapr_cap_hpt_maxpagesize;
 extern const VMStateDescription vmstate_spapr_cap_nested_kvm_hv;
+extern const VMStateDescription vmstate_spapr_cap_nested_papr;
 extern const VMStateDescription vmstate_spapr_cap_large_decr;
 extern const VMStateDescription vmstate_spapr_cap_ccf_assist;
 extern const VMStateDescription vmstate_spapr_cap_fwnmi;