target/ppc: add power-saving interrupt masking logic to p9_next_unmasked_interrupt

Export p9_interrupt_powersave and use it in p9_next_unmasked_interrupt.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20221011204829.1641124-12-matheus.ferst@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

target/ppc/cpu_init.c

@@ -6351,7 +6351,7 @@ static bool ppc_pvr_match_power9(PowerPCCPUClass *pcc, uint32_t pvr, bool best)
     return false;
 }
 
-static int p9_interrupt_powersave(CPUPPCState *env)
+int p9_interrupt_powersave(CPUPPCState *env)
 {
     /* External Exception */
     if ((env->pending_interrupts & PPC_INTERRUPT_EXT) &&

target/ppc/excp_helper.c

@@ -1692,28 +1692,39 @@ void ppc_cpu_do_interrupt(CPUState *cs)
 
 static int p9_next_unmasked_interrupt(CPUPPCState *env)
 {
-    bool async_deliver;
+    PowerPCCPU *cpu = env_archcpu(env);
+    CPUState *cs = CPU(cpu);
+    /* Ignore MSR[EE] when coming out of some power management states */
+    bool msr_ee = FIELD_EX64(env->msr, MSR, EE) || env->resume_as_sreset;
 
     assert((env->pending_interrupts & P9_UNUSED_INTERRUPTS) == 0);
 
+    if (cs->halted) {
+        if (env->spr[SPR_PSSCR] & PSSCR_EC) {
+            /*
+             * When PSSCR[EC] is set, LPCR[PECE] controls which interrupts can
+             * wakeup the processor
+             */
+            return p9_interrupt_powersave(env);
+        } else {
+            /*
+             * When it's clear, any system-caused exception exits power-saving
+             * mode, even the ones that gate on MSR[EE].
+             */
+            msr_ee = true;
+        }
+    }
+
     /* 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) {
+        if ((msr_ee || !FIELD_EX64_HV(env->msr)) && hdice) {
             /* HDEC clears on delivery */
             return PPC_INTERRUPT_HDECR;
         }
@@ -1723,7 +1734,7 @@ static int p9_next_unmasked_interrupt(CPUPPCState *env)
     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) {
+        if ((msr_ee || !FIELD_EX64_HV(env->msr)) && hvice) {
             return PPC_INTERRUPT_HVIRT;
         }
     }
@@ -1733,13 +1744,13 @@ static int p9_next_unmasked_interrupt(CPUPPCState *env)
         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) &&
+        if ((msr_ee && !(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 (async_deliver != 0) {
+    if (msr_ee != 0) {
         /* Decrementer exception */
         if (env->pending_interrupts & PPC_INTERRUPT_DECR) {
             return PPC_INTERRUPT_DECR;
@@ -1901,6 +1912,15 @@ static void p9_deliver_interrupt(CPUPPCState *env, int interrupt)
     PowerPCCPU *cpu = env_archcpu(env);
     CPUState *cs = env_cpu(env);
 
+    if (cs->halted && !(env->spr[SPR_PSSCR] & PSSCR_EC) &&
+        !FIELD_EX64(env->msr, MSR, EE)) {
+        /*
+         * A pending interrupt took us out of power-saving, but MSR[EE] says
+         * that we should return to NIP+4 instead of delivering it.
+         */
+        return;
+    }
+
     switch (interrupt) {
     case PPC_INTERRUPT_MCK: /* Machine check exception */
         env->pending_interrupts &= ~PPC_INTERRUPT_MCK;

target/ppc/internal.h

@@ -306,4 +306,8 @@ static inline int ger_pack_masks(int pmsk, int ymsk, int xmsk)
     return msk;
 }
 
+#if defined(TARGET_PPC64)
+int p9_interrupt_powersave(CPUPPCState *env);
+#endif
+
 #endif /* PPC_INTERNAL_H */