[PATCH v6 1/2] target/s390x: Implement the MVPG condition-code-option bit

[David Hildenbrand]

From: Richard Henderson <richard.henderson@linaro.org>

If the CCO bit is set, MVPG should not generate an exception but
report page translation faults via a CC code.

Create a new helper, access_prepare_nf, which can use probe_access_flags
in non-faulting mode, and then handle watchpoints.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
[thuth: Added logic to still inject protection exceptions]
Signed-off-by: Thomas Huth <thuth@redhat.com>
[david: Look at env->tlb_fill_exc to determine if there was an exception]
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 target/s390x/cpu.h         |   5 ++
 target/s390x/excp_helper.c |   3 +
 target/s390x/mem_helper.c  | 136 ++++++++++++++++++++++++++++++-------
 3 files changed, 121 insertions(+), 23 deletions(-)

diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 60d434d5ed..468b4430f3 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -114,6 +114,11 @@ struct CPUS390XState {
 
     uint64_t diag318_info;
 
+#if !defined(CONFIG_USER_ONLY)
+    uint64_t tlb_fill_tec;   /* translation exception code during tlb_fill */
+    int tlb_fill_exc;        /* exception number seen during tlb_fill */
+#endif
+
     /* Fields up to this point are cleared by a CPU reset */
     struct {} end_reset_fields;
 
diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
index ce16af394b..c48cd6b46f 100644
--- a/target/s390x/excp_helper.c
+++ b/target/s390x/excp_helper.c
@@ -164,6 +164,9 @@ bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int 
size,
         tec = 0; /* unused */
     }
 
+    env->tlb_fill_exc = excp;
+    env->tlb_fill_tec = tec;
+
     if (!excp) {
         qemu_log_mask(CPU_LOG_MMU,
                       "%s: set tlb %" PRIx64 " -> %" PRIx64 " (%x)\n",
diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 25cfede806..6f6e2f80f4 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -130,28 +130,103 @@ typedef struct S390Access {
     int mmu_idx;
 } S390Access;
 
-static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int size,
-                                 MMUAccessType access_type, int mmu_idx,
-                                 uintptr_t ra)
+/*
+ * With nonfault=1, return the PGM_ exception that would have been injected
+ * into the guest; return 0 if no exception was detected.
+ *
+ * For !CONFIG_USER_ONLY, the TEC is stored stored to env->tlb_fill_tec.
+ * For CONFIG_USER_ONLY, the faulting address is stored to env->__excp_addr.
+ */
+static int s390_probe_access(CPUArchState *env, target_ulong addr, int size,
+                             MMUAccessType access_type, int mmu_idx,
+                             bool nonfault, void **phost, uintptr_t ra)
 {
-    S390Access access = {
-        .vaddr1 = vaddr,
-        .size1 = MIN(size, -(vaddr | TARGET_PAGE_MASK)),
-        .mmu_idx = mmu_idx,
-    };
+    int flags;
 
-    g_assert(size > 0 && size <= 4096);
-    access.haddr1 = probe_access(env, access.vaddr1, access.size1, access_type,
-                                 mmu_idx, ra);
+#if defined(CONFIG_USER_ONLY)
+    flags = page_get_flags(addr);
+    if (!(flags & (access_type == MMU_DATA_LOAD ?  PAGE_READ : PAGE_WRITE))) {
+        env->__excp_addr = addr;
+        flags = (flags & PAGE_VALID) ? PGM_PROTECTION : PGM_ADDRESSING;
+        if (nonfault) {
+            return flags;
+        }
+        tcg_s390_program_interrupt(env, flags, ra);
+    }
+    *phost = g2h(env_cpu(env), addr);
+#else
+    /*
+     * For !CONFIG_USER_ONLY, we cannot rely on TLB_INVALID_MASK or haddr==NULL
+     * to detect if there was an exception during tlb_fill().
+     */
+    env->tlb_fill_exc = 0;
+    flags = probe_access_flags(env, addr, access_type, mmu_idx, nonfault, 
phost,
+                               ra);
+    if (env->tlb_fill_exc) {
+        return env->tlb_fill_exc;
+    }
 
-    if (unlikely(access.size1 != size)) {
-        /* The access crosses page boundaries. */
-        access.vaddr2 = wrap_address(env, vaddr + access.size1);
-        access.size2 = size - access.size1;
-        access.haddr2 = probe_access(env, access.vaddr2, access.size2,
-                                     access_type, mmu_idx, ra);
+    if (unlikely(flags & TLB_WATCHPOINT)) {
+        /* S390 does not presently use transaction attributes. */
+        cpu_check_watchpoint(env_cpu(env), addr, size,
+                             MEMTXATTRS_UNSPECIFIED,
+                             (access_type == MMU_DATA_STORE
+                              ? BP_MEM_WRITE : BP_MEM_READ), ra);
     }
-    return access;
+#endif
+    return 0;
+}
+
+static int access_prepare_nf(S390Access *access, CPUS390XState *env,
+                             bool nonfault, vaddr vaddr1, int size,
+                             MMUAccessType access_type,
+                             int mmu_idx, uintptr_t ra)
+{
+    void *haddr1, *haddr2 = NULL;
+    int size1, size2, exc;
+    vaddr vaddr2 = 0;
+
+    assert(size > 0 && size <= 4096);
+
+    size1 = MIN(size, -(vaddr1 | TARGET_PAGE_MASK)),
+    size2 = size - size1;
+
+    exc = s390_probe_access(env, vaddr1, size1, access_type, mmu_idx, nonfault,
+                            &haddr1, ra);
+    if (exc) {
+        return exc;
+    }
+    if (unlikely(size2)) {
+        /* The access crosses page boundaries. */
+        vaddr2 = wrap_address(env, vaddr1 + size1);
+        exc = s390_probe_access(env, vaddr2, size2, access_type, mmu_idx,
+                                nonfault, &haddr2, ra);
+        if (exc) {
+            return exc;
+        }
+    }
+
+    *access = (S390Access) {
+        .vaddr1 = vaddr1,
+        .vaddr2 = vaddr2,
+        .haddr1 = haddr1,
+        .haddr2 = haddr2,
+        .size1 = size1,
+        .size2 = size2,
+        .mmu_idx = mmu_idx
+    };
+    return 0;
+}
+
+static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int size,
+                                 MMUAccessType access_type, int mmu_idx,
+                                 uintptr_t ra)
+{
+    S390Access ret;
+    int exc = access_prepare_nf(&ret, env, false, vaddr, size,
+                                access_type, mmu_idx, ra);
+    assert(!exc);
+    return ret;
 }
 
 /* Helper to handle memset on a single page. */
@@ -845,8 +920,10 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, 
uint64_t r1, uint64_t r2)
     const int mmu_idx = cpu_mmu_index(env, false);
     const bool f = extract64(r0, 11, 1);
     const bool s = extract64(r0, 10, 1);
+    const bool cco = extract64(r0, 8, 1);
     uintptr_t ra = GETPC();
     S390Access srca, desta;
+    int exc;
 
     if ((f && s) || extract64(r0, 12, 4)) {
         tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
@@ -858,13 +935,26 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, 
uint64_t r1, uint64_t r2)
     /*
      * TODO:
      * - Access key handling
-     * - CC-option with surpression of page-translation exceptions
      * - Store r1/r2 register identifiers at real location 162
      */
-    srca = access_prepare(env, r2, TARGET_PAGE_SIZE, MMU_DATA_LOAD, mmu_idx,
-                          ra);
-    desta = access_prepare(env, r1, TARGET_PAGE_SIZE, MMU_DATA_STORE, mmu_idx,
-                           ra);
+    exc = access_prepare_nf(&srca, env, cco, r2, TARGET_PAGE_SIZE,
+                            MMU_DATA_LOAD, mmu_idx, ra);
+    if (exc) {
+        return 2;
+    }
+    exc = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
+                            MMU_DATA_STORE, mmu_idx, ra);
+    if (exc) {
+#if !defined(CONFIG_USER_ONLY)
+        if (exc == PGM_PROTECTION) {
+            stq_phys(env_cpu(env)->as,
+                     env->psa + offsetof(LowCore, trans_exc_code),
+                     env->tlb_fill_tec);
+            tcg_s390_program_interrupt(env, PGM_PROTECTION, ra);
+        }
+#endif
+        return 1;
+    }
     access_memmove(env, &desta, &srca, ra);
     return 0; /* data moved */
 }
-- 
2.29.2