[PATCH v4 3/6] target/ppc: Add SRR1 prefix indication to interrupt handlers

[Nicholas Piggin <npiggin@gmail.com>]

ISA v3.1 introduced prefix instructions. Among the changes, various
synchronous interrupts report whether they were caused by a prefix
instruction in (H)SRR1.

The case of instruction fetch that causes an HDSI due to access of a
process-scoped table faulting on the partition scoped translation is the
tricky one. As with ISIs and HISIs, this does not try to set the prefix
bit because there is no instruction image to be loaded. The HDSI needs
the originating access type to be passed through to the handler to
distinguish this from HDSIs that fault translating process scoped tables
originating from a load or store instruction (in that case the prefix
bit should be provided).

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 target/ppc/excp_helper.c | 44 ++++++++++++++++++++++++++++++++++++++++
 target/ppc/mmu-radix64.c | 14 ++++++++++---
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index 0274617b4a..b4fcaa1d88 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -1348,12 +1348,21 @@ static bool books_vhyp_handles_hv_excp(PowerPCCPU *cpu)
     return false;
 }
 
+static bool is_prefix_excp(CPUPPCState *env, uint32_t insn)
+{
+    if (!(env->insns_flags2 & PPC2_ISA310)) {
+        return false;
+    }
+    return ((insn & 0xfc000000) == 0x04000000);
+}
+
 static void powerpc_excp_books(PowerPCCPU *cpu, int excp)
 {
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
     target_ulong msr, new_msr, vector;
     int srr0, srr1, lev = -1;
+    uint32_t insn = 0;
 
     /* new srr1 value excluding must-be-zero bits */
     msr = env->msr & ~0x783f0000ULL;
@@ -1392,6 +1401,41 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp)
 
     vector |= env->excp_prefix;
 
+    switch (excp) {
+    case POWERPC_EXCP_HDSI:
+        /* HDSI PRTABLE_FAULT has the originating access type in error_code */
+        if ((env->spr[SPR_HDSISR] & DSISR_PRTABLE_FAULT) &&
+            (env->error_code == MMU_INST_FETCH)) {
+            /*
+             * Fetch failed due to partition scope translation, so prefix
+             * indication is not relevant (and attempting to load the
+             * instruction at NIP would cause recursive faults with the same
+             * translation).
+             */
+            break;
+        }
+        /* fall through */
+    case POWERPC_EXCP_MCHECK:
+    case POWERPC_EXCP_DSI:
+    case POWERPC_EXCP_DSEG:
+    case POWERPC_EXCP_ALIGN:
+    case POWERPC_EXCP_PROGRAM:
+    case POWERPC_EXCP_FPU:
+    case POWERPC_EXCP_TRACE:
+    case POWERPC_EXCP_HV_EMU:
+    case POWERPC_EXCP_VPU:
+    case POWERPC_EXCP_VSXU:
+    case POWERPC_EXCP_FU:
+    case POWERPC_EXCP_HV_FU:
+        insn = ppc_ldl_code(env, env->nip);
+        if (is_prefix_excp(env, insn)) {
+            msr |= PPC_BIT(34);
+        }
+        break;
+    default:
+        break;
+    }
+
     switch (excp) {
     case POWERPC_EXCP_MCHECK:    /* Machine check exception                  */
         if (!FIELD_EX64(env->msr, MSR, ME)) {
diff --git a/target/ppc/mmu-radix64.c b/target/ppc/mmu-radix64.c
index 1fc1ba3ecf..920084bd8f 100644
--- a/target/ppc/mmu-radix64.c
+++ b/target/ppc/mmu-radix64.c
@@ -145,6 +145,13 @@ static void ppc_radix64_raise_hsi(PowerPCCPU *cpu, MMUAccessType access_type,
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
 
+    env->error_code = 0;
+    if (cause & DSISR_PRTABLE_FAULT) {
+        /* HDSI PRTABLE_FAULT gets the originating access type in error_code */
+        env->error_code = access_type;
+        access_type = MMU_DATA_LOAD;
+    }
+
     qemu_log_mask(CPU_LOG_MMU, "%s for %s @0x%"VADDR_PRIx" 0x%"
                   HWADDR_PRIx" cause %08x\n",
                   __func__, access_str(access_type),
@@ -166,7 +173,6 @@ static void ppc_radix64_raise_hsi(PowerPCCPU *cpu, MMUAccessType access_type,
         env->spr[SPR_HDSISR] = cause;
         env->spr[SPR_HDAR] = eaddr;
         env->spr[SPR_ASDR] = g_raddr;
-        env->error_code = 0;
         break;
     default:
         g_assert_not_reached();
@@ -369,13 +375,14 @@ static bool validate_pate(PowerPCCPU *cpu, uint64_t lpid, ppc_v3_pate_t *pate)
 }
 
 static int ppc_radix64_partition_scoped_xlate(PowerPCCPU *cpu,
-                                              MMUAccessType access_type,
+                                              MMUAccessType orig_access_type,
                                               vaddr eaddr, hwaddr g_raddr,
                                               ppc_v3_pate_t pate,
                                               hwaddr *h_raddr, int *h_prot,
                                               int *h_page_size, bool pde_addr,
                                               int mmu_idx, bool guest_visible)
 {
+    MMUAccessType access_type = orig_access_type;
     int fault_cause = 0;
     hwaddr pte_addr;
     uint64_t pte;
@@ -404,7 +411,8 @@ static int ppc_radix64_partition_scoped_xlate(PowerPCCPU *cpu,
             fault_cause |= DSISR_PRTABLE_FAULT;
         }
         if (guest_visible) {
-            ppc_radix64_raise_hsi(cpu, access_type, eaddr, g_raddr, fault_cause);
+            ppc_radix64_raise_hsi(cpu, orig_access_type,
+                                  eaddr, g_raddr, fault_cause);
         }
         return 1;
     }
-- 
2.40.1