ppc: Rework POWER7 & POWER8 exception model

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This patch fixes the current AIL implementation for POWER8. The
interrupt vector address can be calculated directly from LPCR when the
exception is handled. The excp_prefix update becomes useless and we
can cleanup the H_SET_MODE hcall.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[clg: Removed LPES0/1 handling for HV vs. !HV
      Fixed LPCR_ILE case for POWERPC_EXCP_POWER8 ]
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com>
[dwg: This was written as a cleanup, but it also fixes a real bug
      where setting an alternative interrupt location would not be
      correctly migrated]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr_hcall.c

@@ -824,7 +824,6 @@ static target_ulong h_set_mode_resource_addr_trans_mode(PowerPCCPU *cpu,
 {
     CPUState *cs;
     PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
-    target_ulong prefix;
 
     if (!(pcc->insns_flags2 & PPC2_ISA207S)) {
         return H_P2;
@@ -836,25 +835,12 @@ static target_ulong h_set_mode_resource_addr_trans_mode(PowerPCCPU *cpu,
         return H_P4;
     }
 
-    switch (mflags) {
+    if (mflags == AIL_RESERVED) {
-    case H_SET_MODE_ADDR_TRANS_NONE:
-        prefix = 0;
-        break;
-    case H_SET_MODE_ADDR_TRANS_0001_8000:
-        prefix = 0x18000;
-        break;
-    case H_SET_MODE_ADDR_TRANS_C000_0000_0000_4000:
-        prefix = 0xC000000000004000ULL;
-        break;
-    default:
         return H_UNSUPPORTED_FLAG;
     }
 
     CPU_FOREACH(cs) {
-        CPUPPCState *env = &POWERPC_CPU(cpu)->env;
-
         set_spr(cs, SPR_LPCR, mflags << LPCR_AIL_SHIFT, LPCR_AIL);
-        env->excp_prefix = prefix;
     }
 
     return H_SUCCESS;

include/hw/ppc/spapr.h

@@ -204,11 +204,6 @@ struct sPAPRMachineState {
 #define H_SET_MODE_ENDIAN_BIG    0
 #define H_SET_MODE_ENDIAN_LITTLE 1
 
-/* Flags for H_SET_MODE_RESOURCE_ADDR_TRANS_MODE */
-#define H_SET_MODE_ADDR_TRANS_NONE                  0
-#define H_SET_MODE_ADDR_TRANS_0001_8000             2
-#define H_SET_MODE_ADDR_TRANS_C000_0000_0000_4000   3
-
 /* VASI States */
 #define H_VASI_INVALID    0
 #define H_VASI_ENABLED    1

target-ppc/cpu.h

@@ -167,6 +167,8 @@ enum powerpc_excp_t {
     POWERPC_EXCP_970,
     /* POWER7 exception model           */
     POWERPC_EXCP_POWER7,
+    /* POWER8 exception model           */
+    POWERPC_EXCP_POWER8,
 #endif /* defined(TARGET_PPC64) */
 };
 
@@ -2277,6 +2279,14 @@ enum {
     HMER_XSCOM_STATUS_LSH       = (63 - 23),
 };
 
+/* Alternate Interrupt Location (AIL) */
+enum {
+    AIL_NONE                = 0,
+    AIL_RESERVED            = 1,
+    AIL_0001_8000           = 2,
+    AIL_C000_0000_0000_4000 = 3,
+};
+
 /*****************************************************************************/
 
 static inline target_ulong cpu_read_xer(CPUPPCState *env)

target-ppc/excp_helper.c

@@ -77,7 +77,7 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
     CPUPPCState *env = &cpu->env;
     target_ulong msr, new_msr, vector;
     int srr0, srr1, asrr0, asrr1;
-    int lpes0, lpes1, lev;
+    int lpes0, lpes1, lev, ail;
 
     if (0) {
         /* XXX: find a suitable condition to enable the hypervisor mode */
@@ -108,6 +108,25 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
     asrr0 = -1;
     asrr1 = -1;
 
+    /* Exception targetting modifiers
+     *
+     * AIL is initialized here but can be cleared by
+     * selected exceptions
+     */
+#if defined(TARGET_PPC64)
+    if (excp_model == POWERPC_EXCP_POWER7 ||
+        excp_model == POWERPC_EXCP_POWER8) {
+        if (excp_model == POWERPC_EXCP_POWER8) {
+            ail = (env->spr[SPR_LPCR] & LPCR_AIL) >> LPCR_AIL_SHIFT;
+        } else {
+            ail = 0;
+        }
+    } else
+#endif /* defined(TARGET_PPC64) */
+    {
+        ail = 0;
+    }
+
     switch (excp) {
     case POWERPC_EXCP_NONE:
         /* Should never happen */
@@ -146,6 +165,7 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
             /* XXX: find a suitable condition to enable the hypervisor mode */
             new_msr |= (target_ulong)MSR_HVB;
         }
+        ail = 0;
 
         /* machine check exceptions don't have ME set */
         new_msr &= ~((target_ulong)1 << MSR_ME);
@@ -344,6 +364,7 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
             /* XXX: find a suitable condition to enable the hypervisor mode */
             new_msr |= (target_ulong)MSR_HVB;
         }
+        ail = 0;
         goto store_next;
     case POWERPC_EXCP_DSEG:      /* Data segment exception                   */
         if (lpes1 == 0) {
@@ -630,7 +651,8 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
     }
 
 #ifdef TARGET_PPC64
-    if (excp_model == POWERPC_EXCP_POWER7) {
+    if (excp_model == POWERPC_EXCP_POWER7 ||
+        excp_model == POWERPC_EXCP_POWER8) {
         if (env->spr[SPR_LPCR] & LPCR_ILE) {
             new_msr |= (target_ulong)1 << MSR_LE;
         }
@@ -650,6 +672,29 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int excp_model, int excp)
                   excp);
     }
     vector |= env->excp_prefix;
+
+    /* AIL only works if there is no HV transition and we are running with
+     * translations enabled
+     */
+    if (!((msr >> MSR_IR) & 1) || !((msr >> MSR_DR) & 1)) {
+        ail = 0;
+    }
+    /* Handle AIL */
+    if (ail) {
+        new_msr |= (1 << MSR_IR) | (1 << MSR_DR);
+        switch(ail) {
+        case AIL_0001_8000:
+            vector |= 0x18000;
+            break;
+        case AIL_C000_0000_0000_4000:
+            vector |= 0xc000000000004000ull;
+            break;
+        default:
+            cpu_abort(cs, "Invalid AIL combination %d\n", ail);
+            break;
+        }
+    }
+
 #if defined(TARGET_PPC64)
     if (excp_model == POWERPC_EXCP_BOOKE) {
         if (env->spr[SPR_BOOKE_EPCR] & EPCR_ICM) {

target-ppc/translate_init.c

@@ -8487,7 +8487,7 @@ POWERPC_FAMILY(POWER8)(ObjectClass *oc, void *data)
     pcc->handle_mmu_fault = ppc_hash64_handle_mmu_fault;
     pcc->sps = &POWER7_POWER8_sps;
 #endif
-    pcc->excp_model = POWERPC_EXCP_POWER7;
+    pcc->excp_model = POWERPC_EXCP_POWER8;
     pcc->bus_model = PPC_FLAGS_INPUT_POWER7;
     pcc->bfd_mach = bfd_mach_ppc64;
     pcc->flags = POWERPC_FLAG_VRE | POWERPC_FLAG_SE |