target/ppc: create an interrupt masking method for POWER8

The new method is identical to ppc_next_unmasked_interrupt_generic,
processor-specific code will be added/removed in the following patches.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20221011204829.1641124-13-matheus.ferst@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

target/ppc/excp_helper.c

@@ -1685,6 +1685,112 @@ void ppc_cpu_do_interrupt(CPUState *cs)
 }
 
 #if defined(TARGET_PPC64)
+static int p8_next_unmasked_interrupt(CPUPPCState *env)
+{
+    bool async_deliver;
+
+    /* External reset */
+    if (env->pending_interrupts & PPC_INTERRUPT_RESET) {
+        return PPC_INTERRUPT_RESET;
+    }
+    /* Machine check exception */
+    if (env->pending_interrupts & PPC_INTERRUPT_MCK) {
+        return PPC_INTERRUPT_MCK;
+    }
+
+    /*
+     * For interrupts that gate on MSR:EE, we need to do something a
+     * bit more subtle, as we need to let them through even when EE is
+     * clear when coming out of some power management states (in order
+     * for them to become a 0x100).
+     */
+    async_deliver = FIELD_EX64(env->msr, MSR, EE) || env->resume_as_sreset;
+
+    /* Hypervisor decrementer exception */
+    if (env->pending_interrupts & PPC_INTERRUPT_HDECR) {
+        /* LPCR will be clear when not supported so this will work */
+        bool hdice = !!(env->spr[SPR_LPCR] & LPCR_HDICE);
+        if ((async_deliver || !FIELD_EX64_HV(env->msr)) && hdice) {
+            /* HDEC clears on delivery */
+            return PPC_INTERRUPT_HDECR;
+        }
+    }
+
+    /* Hypervisor virtualization interrupt */
+    if (env->pending_interrupts & PPC_INTERRUPT_HVIRT) {
+        /* LPCR will be clear when not supported so this will work */
+        bool hvice = !!(env->spr[SPR_LPCR] & LPCR_HVICE);
+        if ((async_deliver || !FIELD_EX64_HV(env->msr)) && hvice) {
+            return PPC_INTERRUPT_HVIRT;
+        }
+    }
+
+    /* External interrupt can ignore MSR:EE under some circumstances */
+    if (env->pending_interrupts & PPC_INTERRUPT_EXT) {
+        bool lpes0 = !!(env->spr[SPR_LPCR] & LPCR_LPES0);
+        bool heic = !!(env->spr[SPR_LPCR] & LPCR_HEIC);
+        /* HEIC blocks delivery to the hypervisor */
+        if ((async_deliver && !(heic && FIELD_EX64_HV(env->msr) &&
+            !FIELD_EX64(env->msr, MSR, PR))) ||
+            (env->has_hv_mode && !FIELD_EX64_HV(env->msr) && !lpes0)) {
+            return PPC_INTERRUPT_EXT;
+        }
+    }
+    if (FIELD_EX64(env->msr, MSR, CE)) {
+        /* External critical interrupt */
+        if (env->pending_interrupts & PPC_INTERRUPT_CEXT) {
+            return PPC_INTERRUPT_CEXT;
+        }
+    }
+    if (async_deliver != 0) {
+        /* Watchdog timer on embedded PowerPC */
+        if (env->pending_interrupts & PPC_INTERRUPT_WDT) {
+            return PPC_INTERRUPT_WDT;
+        }
+        if (env->pending_interrupts & PPC_INTERRUPT_CDOORBELL) {
+            return PPC_INTERRUPT_CDOORBELL;
+        }
+        /* Fixed interval timer on embedded PowerPC */
+        if (env->pending_interrupts & PPC_INTERRUPT_FIT) {
+            return PPC_INTERRUPT_FIT;
+        }
+        /* Programmable interval timer on embedded PowerPC */
+        if (env->pending_interrupts & PPC_INTERRUPT_PIT) {
+            return PPC_INTERRUPT_PIT;
+        }
+        /* Decrementer exception */
+        if (env->pending_interrupts & PPC_INTERRUPT_DECR) {
+            return PPC_INTERRUPT_DECR;
+        }
+        if (env->pending_interrupts & PPC_INTERRUPT_DOORBELL) {
+            return PPC_INTERRUPT_DOORBELL;
+        }
+        if (env->pending_interrupts & PPC_INTERRUPT_HDOORBELL) {
+            return PPC_INTERRUPT_HDOORBELL;
+        }
+        if (env->pending_interrupts & PPC_INTERRUPT_PERFM) {
+            return PPC_INTERRUPT_PERFM;
+        }
+        /* Thermal interrupt */
+        if (env->pending_interrupts & PPC_INTERRUPT_THERM) {
+            return PPC_INTERRUPT_THERM;
+        }
+        /* EBB exception */
+        if (env->pending_interrupts & PPC_INTERRUPT_EBB) {
+            /*
+             * EBB exception must be taken in problem state and
+             * with BESCR_GE set.
+             */
+            if (FIELD_EX64(env->msr, MSR, PR) &&
+                (env->spr[SPR_BESCR] & BESCR_GE)) {
+                return PPC_INTERRUPT_EBB;
+            }
+        }
+    }
+
+    return 0;
+}
+
 #define P9_UNUSED_INTERRUPTS \
     (PPC_INTERRUPT_RESET | PPC_INTERRUPT_DEBUG | PPC_INTERRUPT_CEXT |   \
      PPC_INTERRUPT_WDT | PPC_INTERRUPT_CDOORBELL | PPC_INTERRUPT_FIT |  \
@@ -1897,6 +2003,8 @@ static int ppc_next_unmasked_interrupt(CPUPPCState *env)
 {
     switch (env->excp_model) {
 #if defined(TARGET_PPC64)
+    case POWERPC_EXCP_POWER8:
+        return p8_next_unmasked_interrupt(env);
     case POWERPC_EXCP_POWER9:
     case POWERPC_EXCP_POWER10:
         return p9_next_unmasked_interrupt(env);