target/ppc/spapr: Add SPAPR_CAP_LARGE_DECREMENTER

Add spapr_cap SPAPR_CAP_LARGE_DECREMENTER to be used to control the
availability of the large decrementer for a guest.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Message-Id: <20190301024317.22137-1-sjitindarsingh@gmail.com>
[dwg: Trivial style fix]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -2088,6 +2088,7 @@ static const VMStateDescription vmstate_spapr = {
         &vmstate_spapr_irq_map,
         &vmstate_spapr_cap_nested_kvm_hv,
         &vmstate_spapr_dtb,
+        &vmstate_spapr_cap_large_decr,
         NULL
     }
 };
@@ -4302,6 +4303,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     smc->default_caps.caps[SPAPR_CAP_IBS] = SPAPR_CAP_BROKEN;
     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_OFF;
     spapr_caps_add_properties(smc, &error_abort);
     smc->irq = &spapr_irq_xics;
     smc->dr_phb_enabled = true;

hw/ppc/spapr_caps.c

@@ -390,6 +390,14 @@ static void cap_nested_kvm_hv_apply(sPAPRMachineState *spapr,
     }
 }
 
+static void cap_large_decr_apply(sPAPRMachineState *spapr,
+                                 uint8_t val, Error **errp)
+{
+    if (val)
+        error_setg(errp,
+                   "No large decrementer support, try cap-large-decr=off");
+}
+
 sPAPRCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
     [SPAPR_CAP_HTM] = {
         .name = "htm",
@@ -468,6 +476,15 @@ sPAPRCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
         .type = "bool",
         .apply = cap_nested_kvm_hv_apply,
     },
+    [SPAPR_CAP_LARGE_DECREMENTER] = {
+        .name = "large-decr",
+        .description = "Allow Large Decrementer",
+        .index = SPAPR_CAP_LARGE_DECREMENTER,
+        .get = spapr_cap_get_bool,
+        .set = spapr_cap_set_bool,
+        .type = "bool",
+        .apply = cap_large_decr_apply,
+    },
 };
 
 static sPAPRCapabilities default_caps_with_cpu(sPAPRMachineState *spapr,
@@ -596,6 +613,7 @@ SPAPR_CAP_MIG_STATE(cfpc, SPAPR_CAP_CFPC);
 SPAPR_CAP_MIG_STATE(sbbc, SPAPR_CAP_SBBC);
 SPAPR_CAP_MIG_STATE(ibs, SPAPR_CAP_IBS);
 SPAPR_CAP_MIG_STATE(nested_kvm_hv, SPAPR_CAP_NESTED_KVM_HV);
+SPAPR_CAP_MIG_STATE(large_decr, SPAPR_CAP_LARGE_DECREMENTER);
 
 void spapr_caps_init(sPAPRMachineState *spapr)
 {

include/hw/ppc/spapr.h

@@ -74,8 +74,10 @@ typedef enum {
 #define SPAPR_CAP_HPT_MAXPAGESIZE       0x06
 /* Nested KVM-HV */
 #define SPAPR_CAP_NESTED_KVM_HV         0x07
+/* Large Decrementer */
+#define SPAPR_CAP_LARGE_DECREMENTER     0x08
 /* Num Caps */
-#define SPAPR_CAP_NUM                   (SPAPR_CAP_NESTED_KVM_HV + 1)
+#define SPAPR_CAP_NUM                   (SPAPR_CAP_LARGE_DECREMENTER + 1)
 
 /*
  * Capability Values
@@ -828,6 +830,7 @@ extern const VMStateDescription vmstate_spapr_cap_cfpc;
 extern const VMStateDescription vmstate_spapr_cap_sbbc;
 extern const VMStateDescription vmstate_spapr_cap_ibs;
 extern const VMStateDescription vmstate_spapr_cap_nested_kvm_hv;
+extern const VMStateDescription vmstate_spapr_cap_large_decr;
 
 static inline uint8_t spapr_get_cap(sPAPRMachineState *spapr, int cap)
 {