[PATCH v1 3/5] s390x/mmu: Implement Instruction-Execution-Protection Facility

[David Hildenbrand <david@redhat.com>]

IEP support in the mmu is fairly easy. Set the right permissions for TLB
entries and properly report an exception.

Make sure to handle EDAT-2 by setting bit 56/60/61 of the TEID (TEC) to
the right values.

Let's keep s390_cpu_get_phys_page_debug() working even if IEP is
active. Switch MMU_DATA_LOAD - this has no other effects any more as the
ASC to be used is now fully selected outside of mmu_translate().

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 target/s390x/cpu.h        |  1 +
 target/s390x/helper.c     |  6 +++++-
 target/s390x/mmu_helper.c | 21 +++++++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 690b94c8ea..6eb7c07013 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -315,6 +315,7 @@ extern const VMStateDescription vmstate_s390_cpu;
 #define CR0_EDAT                0x0000000000800000ULL
 #define CR0_AFP                 0x0000000000040000ULL
 #define CR0_VECTOR              0x0000000000020000ULL
+#define CR0_IEP                 0x0000000000100000ULL
 #define CR0_EMERGENCY_SIGNAL_SC 0x0000000000004000ULL
 #define CR0_EXTERNAL_CALL_SC    0x0000000000002000ULL
 #define CR0_CKC_SC              0x0000000000000800ULL
diff --git a/target/s390x/helper.c b/target/s390x/helper.c
index 948c0398d4..bf503b56ee 100644
--- a/target/s390x/helper.c
+++ b/target/s390x/helper.c
@@ -63,7 +63,11 @@ hwaddr s390_cpu_get_phys_page_debug(CPUState *cs, vaddr vaddr)
         asc = PSW_ASC_PRIMARY;
     }
 
-    if (mmu_translate(env, vaddr, MMU_INST_FETCH, asc, &raddr, &prot, false)) {
+    /*
+     * We want to read code even if IEP is active. Use MMU_DATA_LOAD instead
+     * of MMU_INST_FETCH.
+     */
+    if (mmu_translate(env, vaddr, MMU_DATA_LOAD, asc, &raddr, &prot, false)) {
         return -1;
     }
     return raddr;
diff --git a/target/s390x/mmu_helper.c b/target/s390x/mmu_helper.c
index 8abc5d31d8..ff8b077f82 100644
--- a/target/s390x/mmu_helper.c
+++ b/target/s390x/mmu_helper.c
@@ -121,6 +121,8 @@ static int mmu_translate_asce(CPUS390XState *env, target_ulong vaddr,
     const bool edat1 = (env->cregs[0] & CR0_EDAT) &&
                        s390_has_feat(S390_FEAT_EDAT);
     const bool edat2 = edat1 && s390_has_feat(S390_FEAT_EDAT_2);
+    const bool iep = (env->cregs[0] & CR0_IEP) &&
+                     s390_has_feat(S390_FEAT_INSTRUCTION_EXEC_PROT);
     const int asce_tl = asce & ASCE_TABLE_LENGTH;
     const int asce_p = asce & ASCE_PRIVATE_SPACE;
     hwaddr gaddr = asce & ASCE_ORIGIN;
@@ -227,6 +229,9 @@ static int mmu_translate_asce(CPUS390XState *env, target_ulong vaddr,
             *flags &= ~PAGE_WRITE;
         }
         if (edat2 && (entry & REGION3_ENTRY_FC)) {
+            if (iep && (entry & REGION3_ENTRY_IEP)) {
+                *flags &= ~PAGE_EXEC;
+            }
             *raddr = (entry & REGION3_ENTRY_RFAA) |
                      (vaddr & REGION3_ENTRY_RFAA);
             return 0;
@@ -254,6 +259,9 @@ static int mmu_translate_asce(CPUS390XState *env, target_ulong vaddr,
             *flags &= ~PAGE_WRITE;
         }
         if (edat1 && (entry & SEGMENT_ENTRY_FC)) {
+            if (iep && (entry & SEGMENT_ENTRY_IEP)) {
+                *flags &= ~PAGE_EXEC;
+            }
             *raddr = (entry & SEGMENT_ENTRY_SFAA) |
                      (vaddr & ~SEGMENT_ENTRY_SFAA);
             return 0;
@@ -276,6 +284,9 @@ static int mmu_translate_asce(CPUS390XState *env, target_ulong vaddr,
     if (entry & PAGE_ENTRY_P) {
         *flags &= ~PAGE_WRITE;
     }
+    if (iep && (entry & PAGE_ENTRY_IEP)) {
+        *flags &= ~PAGE_EXEC;
+    }
 
     *raddr = entry & TARGET_PAGE_MASK;
     return 0;
@@ -434,6 +445,16 @@ int mmu_translate(CPUS390XState *env, target_ulong vaddr, int rw, uint64_t asc,
         return -1;
     }
 
+    /* check for Instruction-Execution-Protection */
+    if (unlikely(rw == MMU_INST_FETCH && !(*flags & PAGE_EXEC))) {
+        if (exc) {
+            /* IEP sets bit 56 and 61 */
+            tec |= 0x84;
+            trigger_access_exception(env, PGM_PROTECTION, ilen, tec);
+        }
+        return -1;
+    }
+
 nodat:
     /* Convert real address -> absolute address */
     *raddr = mmu_real2abs(env, *raddr);
-- 
2.21.0