[PATCH v3] target/ppc: Machine check on invalid real address access on POWER9/10

[Nicholas Piggin <npiggin@gmail.com>]

ppc currently silently accepts invalid real address access. Catch
these and turn them into machine checks on POWER9/10 machines.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
Since v1:
- Only implement this for POWER9/10. Seems like previous IBM processors
  may not catch this, trying to get info.

Since v2:
- Split out from larger series since it is independent.

 target/ppc/cpu_init.c    |  1 +
 target/ppc/excp_helper.c | 49 ++++++++++++++++++++++++++++++++++++++++
 target/ppc/internal.h    |  5 ++++
 3 files changed, 55 insertions(+)

diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
index 720aad9e05..6ac1765a8d 100644
--- a/target/ppc/cpu_init.c
+++ b/target/ppc/cpu_init.c
@@ -7335,6 +7335,7 @@ static const struct TCGCPUOps ppc_tcg_ops = {
   .cpu_exec_enter = ppc_cpu_exec_enter,
   .cpu_exec_exit = ppc_cpu_exec_exit,
   .do_unaligned_access = ppc_cpu_do_unaligned_access,
+  .do_transaction_failed = ppc_cpu_do_transaction_failed,
 #endif /* !CONFIG_USER_ONLY */
 };
 #endif /* CONFIG_TCG */
diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index 354392668e..e49e13a30d 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -1428,7 +1428,9 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp)
         /* machine check exceptions don't have ME set */
         new_msr &= ~((target_ulong)1 << MSR_ME);
 
+        msr |= env->error_code;
         break;
+
     case POWERPC_EXCP_DSI:       /* Data storage exception                   */
         trace_ppc_excp_dsi(env->spr[SPR_DSISR], env->spr[SPR_DAR]);
         break;
@@ -3184,5 +3186,52 @@ void ppc_cpu_do_unaligned_access(CPUState *cs, vaddr vaddr,
     env->error_code = insn & 0x03FF0000;
     cpu_loop_exit(cs);
 }
+
+void ppc_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr,
+                                   vaddr vaddr, unsigned size,
+                                   MMUAccessType access_type,
+                                   int mmu_idx, MemTxAttrs attrs,
+                                   MemTxResult response, uintptr_t retaddr)
+{
+    CPUPPCState *env = cs->env_ptr;
+
+    switch (env->excp_model) {
+#if defined(TARGET_PPC64)
+    case POWERPC_EXCP_POWER9:
+    case POWERPC_EXCP_POWER10:
+        /*
+         * Machine check codes can be found in processor User Manual or
+         * Linux or skiboot source.
+         */
+        if (access_type == MMU_DATA_LOAD) {
+            env->spr[SPR_DAR] = vaddr;
+            env->spr[SPR_DSISR] = PPC_BIT(57);
+            env->error_code = PPC_BIT(42);
+
+        } else if (access_type == MMU_DATA_STORE) {
+            /*
+             * MCE for stores in POWER is asynchronous so hardware does
+             * not set DAR, but QEMU can do better.
+             */
+            env->spr[SPR_DAR] = vaddr;
+            env->error_code = PPC_BIT(36) | PPC_BIT(43) | PPC_BIT(45);
+            env->error_code |= PPC_BIT(42);
+
+        } else { /* Fetch */
+            env->error_code = PPC_BIT(36) | PPC_BIT(44) | PPC_BIT(45);
+        }
+        break;
+#endif
+    default:
+        /*
+         * TODO: Check behaviour for other CPUs, for now do nothing.
+         * Could add a basic MCE even if real hardware ignores.
+         */
+        return;
+    }
+
+    cs->exception_index = POWERPC_EXCP_MCHECK;
+    cpu_loop_exit_restore(cs, retaddr);
+}
 #endif /* CONFIG_TCG */
 #endif /* !CONFIG_USER_ONLY */
diff --git a/target/ppc/internal.h b/target/ppc/internal.h
index 901bae6d39..57acb3212c 100644
--- a/target/ppc/internal.h
+++ b/target/ppc/internal.h
@@ -296,6 +296,11 @@ bool ppc_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
 G_NORETURN void ppc_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
                                             MMUAccessType access_type, int mmu_idx,
                                             uintptr_t retaddr);
+void ppc_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr,
+                                   vaddr addr, unsigned size,
+                                   MMUAccessType access_type,
+                                   int mmu_idx, MemTxAttrs attrs,
+                                   MemTxResult response, uintptr_t retaddr);
 #endif
 
 FIELD(GER_MSK, XMSK, 0, 4)
-- 
2.40.1