target/ppc: Assert if MSR bits differ from msr_mask during exceptions

We currently abort QEMU during the dispatch of an interrupt if we try
to set MSR_HV without having MSR_HVB in the msr_mask. I think we
should verify this for all MSR bits. There is no reason to ever have a
MSR bit set if the corresponding bit is not set in that CPU's
msr_mask.

Note that this is not about the emulated code setting reserved
bits. We clear the new_msr when starting to dispatch an exception, so
if we end up with bits not present in the msr_mask that is a QEMU
programming error.

I kept the HSRR verification for BookS because it is the only CPU
family that has HSRRs.

Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20220207183036.1507882-4-farosas@linux.ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

1 files changed, 6 insertions, 58 deletions

diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
index acdeeb4059..83be6698df 100644
--- a/target/ppc/excp_helper.c
+++ b/target/ppc/excp_helper.c
@@ -364,6 +364,8 @@ static void powerpc_set_excp_state(PowerPCCPU *cpu,
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
 
+    assert((msr & env->msr_mask) == msr);
+
     /*
      * We don't use hreg_store_msr here as already have treated any
      * special case that could occur. Just store MSR and update hflags
@@ -372,7 +374,7 @@ static void powerpc_set_excp_state(PowerPCCPU *cpu,
      * will prevent setting of the HV bit which some exceptions might need
      * to do.
      */
-    env->msr = msr & env->msr_mask;
+    env->msr = msr;
     hreg_compute_hflags(env);
     env->nip = vector;
     /* Reset exception state */
@@ -519,18 +521,6 @@ static void powerpc_excp_40x(PowerPCCPU *cpu, int excp)
         break;
     }
 
-    /* Sanity check */
-    if (!(env->msr_mask & MSR_HVB)) {
-        if (new_msr & MSR_HVB) {
-            cpu_abort(cs, "Trying to deliver HV exception (MSR) %d with "
-                      "no HV support\n", excp);
-        }
-        if (srr0 == SPR_HSRR0) {
-            cpu_abort(cs, "Trying to deliver HV exception (HSRR) %d with "
-                      "no HV support\n", excp);
-        }
-    }
-
     /* Save PC */
     env->spr[srr0] = env->nip;
 
@@ -699,14 +689,6 @@ static void powerpc_excp_6xx(PowerPCCPU *cpu, int excp)
         break;
     }
 
-    /* Sanity check */
-    if (!(env->msr_mask & MSR_HVB)) {
-        if (new_msr & MSR_HVB) {
-            cpu_abort(cs, "Trying to deliver HV exception (MSR) %d with "
-                      "no HV support\n", excp);
-        }
-    }
-
     /*
      * Sort out endianness of interrupt, this differs depending on the
      * CPU, the HV mode, etc...
@@ -893,14 +875,6 @@ static void powerpc_excp_7xx(PowerPCCPU *cpu, int excp)
         break;
     }
 
-    /* Sanity check */
-    if (!(env->msr_mask & MSR_HVB)) {
-        if (new_msr & MSR_HVB) {
-            cpu_abort(cs, "Trying to deliver HV exception (MSR) %d with "
-                      "no HV support\n", excp);
-        }
-    }
-
     /*
      * Sort out endianness of interrupt, this differs depending on the
      * CPU, the HV mode, etc...
@@ -1079,14 +1053,6 @@ static void powerpc_excp_74xx(PowerPCCPU *cpu, int excp)
         break;
     }
 
-    /* Sanity check */
-    if (!(env->msr_mask & MSR_HVB)) {
-        if (new_msr & MSR_HVB) {
-            cpu_abort(cs, "Trying to deliver HV exception (MSR) %d with "
-                      "no HV support\n", excp);
-        }
-    }
-
     /*
      * Sort out endianness of interrupt, this differs depending on the
      * CPU, the HV mode, etc...
@@ -1291,18 +1257,6 @@ static void powerpc_excp_booke(PowerPCCPU *cpu, int excp)
         break;
     }
 
-    /* Sanity check */
-    if (!(env->msr_mask & MSR_HVB)) {
-        if (new_msr & MSR_HVB) {
-            cpu_abort(cs, "Trying to deliver HV exception (MSR) %d with "
-                      "no HV support\n", excp);
-        }
-        if (srr0 == SPR_HSRR0) {
-            cpu_abort(cs, "Trying to deliver HV exception (HSRR) %d with "
-                      "no HV support\n", excp);
-        }
-    }
-
 #if defined(TARGET_PPC64)
     if (env->spr[SPR_BOOKE_EPCR] & EPCR_ICM) {
         /* Cat.64-bit: EPCR.ICM is copied to MSR.CM */
@@ -1573,15 +1527,9 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp)
     }
 
     /* Sanity check */
-    if (!(env->msr_mask & MSR_HVB)) {
-        if (new_msr & MSR_HVB) {
-            cpu_abort(cs, "Trying to deliver HV exception (MSR) %d with "
-                      "no HV support\n", excp);
-        }
-        if (srr0 == SPR_HSRR0) {
-            cpu_abort(cs, "Trying to deliver HV exception (HSRR) %d with "
-                      "no HV support\n", excp);
-        }
+    if (!(env->msr_mask & MSR_HVB) && srr0 == SPR_HSRR0) {
+        cpu_abort(cs, "Trying to deliver HV exception (HSRR) %d with "
+                  "no HV support\n", excp);
     }
 
     /*