s390x/mmu_helper: move address validation into mmu_translate*()

Let's move address validation into mmu_translate() and
mmu_translate_real(). This allows for checking whether an absolute
address is valid before looking up the storage key. We can now get rid of
the ram_size check.

Interestingly, we're already handling LOAD REAL ADDRESS wrong, because
a) We're not supposed to touch storage keys
b) We're not supposed to convert to an absolute address

Let's use a fake, negative MMUAccessType to teach mmu_translate() to
fix that handling and to not perform address validation.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210903155514.44772-8-david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

4 files changed, 24 insertions, 29 deletions

diff --git a/target/s390x/mmu_helper.c b/target/s390x/mmu_helper.c
index ca25dad..de6df92 100644
--- a/target/s390x/mmu_helper.c
+++ b/target/s390x/mmu_helper.c
@@ -301,14 +301,13 @@ static void mmu_handle_skey(target_ulong addr, int rw, int *flags)
 {
     static S390SKeysClass *skeyclass;
     static S390SKeysState *ss;
-    MachineState *ms = MACHINE(qdev_get_machine());
     uint8_t key;
     int rc;
 
-    if (unlikely(addr >= ms->ram_size)) {
-        return;
-    }
-
+    /*
+     * We expect to be called with an absolute address that has already been
+     * validated, such that we can reliably use it to lookup the storage key.
+     */
     if (unlikely(!ss)) {
         ss = s390_get_skeys_device();
         skeyclass = S390_SKEYS_GET_CLASS(ss);
@@ -370,7 +369,7 @@ static void mmu_handle_skey(target_ulong addr, int rw, int *flags)
 /**
  * Translate a virtual (logical) address into a physical (absolute) address.
  * @param vaddr  the virtual address
- * @param rw     0 = read, 1 = write, 2 = code fetch
+ * @param rw     0 = read, 1 = write, 2 = code fetch, < 0 = load real address
  * @param asc    address space control (one of the PSW_ASC_* modes)
  * @param raddr  the translated address is stored to this pointer
  * @param flags  the PAGE_READ/WRITE/EXEC flags are stored to this pointer
@@ -449,10 +448,17 @@ int mmu_translate(CPUS390XState *env, target_ulong vaddr, int rw, uint64_t asc,
     }
 
 nodat:
-    /* Convert real address -> absolute address */
-    *raddr = mmu_real2abs(env, *raddr);
+    if (rw >= 0) {
+        /* Convert real address -> absolute address */
+        *raddr = mmu_real2abs(env, *raddr);
 
-    mmu_handle_skey(*raddr, rw, flags);
+        if (!mmu_absolute_addr_valid(*raddr, rw == MMU_DATA_STORE)) {
+            *tec = 0; /* unused */
+            return PGM_ADDRESSING;
+        }
+
+        mmu_handle_skey(*raddr, rw, flags);
+    }
     return 0;
 }
 
@@ -473,12 +479,6 @@ static int translate_pages(S390CPU *cpu, vaddr addr, int nr_pages,
         if (ret) {
             return ret;
         }
-        if (!address_space_access_valid(&address_space_memory, pages[i],
-                                        TARGET_PAGE_SIZE, is_write,
-                                        MEMTXATTRS_UNSPECIFIED)) {
-            *tec = 0; /* unused */
-            return PGM_ADDRESSING;
-        }
         addr += TARGET_PAGE_SIZE;
     }
 
@@ -588,6 +588,12 @@ int mmu_translate_real(CPUS390XState *env, target_ulong raddr, int rw,
 
     *addr = mmu_real2abs(env, raddr & TARGET_PAGE_MASK);
 
+    if (!mmu_absolute_addr_valid(*addr, rw == MMU_DATA_STORE)) {
+        /* unused */
+        *tec = 0;
+        return PGM_ADDRESSING;
+    }
+
     mmu_handle_skey(*addr, rw, flags);
     return 0;
 }
diff --git a/target/s390x/s390x-internal.h b/target/s390x/s390x-internal.h
index d246d26..7a6aa4d 100644
--- a/target/s390x/s390x-internal.h
+++ b/target/s390x/s390x-internal.h
@@ -374,6 +374,8 @@ void probe_write_access(CPUS390XState *env, uint64_t addr, uint64_t len,
 
 /* mmu_helper.c */
 bool mmu_absolute_addr_valid(target_ulong addr, bool is_write);
+/* Special access mode only valid for mmu_translate() */
+#define MMU_S390_LRA        -1
 int mmu_translate(CPUS390XState *env, target_ulong vaddr, int rw, uint64_t asc,
                   target_ulong *raddr, int *flags, uint64_t *tec);
 int mmu_translate_real(CPUS390XState *env, target_ulong raddr, int rw,
diff --git a/target/s390x/tcg/excp_helper.c b/target/s390x/tcg/excp_helper.c
index a61917d..3d6662a 100644
--- a/target/s390x/tcg/excp_helper.c
+++ b/target/s390x/tcg/excp_helper.c
@@ -150,19 +150,6 @@ bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
         g_assert_not_reached();
     }
 
-    /* check out of RAM access */
-    if (!excp &&
-        !address_space_access_valid(&address_space_memory, raddr,
-                                    TARGET_PAGE_SIZE, access_type,
-                                    MEMTXATTRS_UNSPECIFIED)) {
-        MachineState *ms = MACHINE(qdev_get_machine());
-        qemu_log_mask(CPU_LOG_MMU,
-                      "%s: raddr %" PRIx64 " > ram_size %" PRIx64 "\n",
-                      __func__, (uint64_t)raddr, (uint64_t)ms->ram_size);
-        excp = PGM_ADDRESSING;
-        tec = 0; /* unused */
-    }
-
     env->tlb_fill_exc = excp;
     env->tlb_fill_tec = tec;
 
diff --git a/target/s390x/tcg/mem_helper.c b/target/s390x/tcg/mem_helper.c
index a44a107..4f9f3e1 100644
--- a/target/s390x/tcg/mem_helper.c
+++ b/target/s390x/tcg/mem_helper.c
@@ -2455,7 +2455,7 @@ uint64_t HELPER(lra)(CPUS390XState *env, uint64_t addr)
         tcg_s390_program_interrupt(env, PGM_SPECIAL_OP, GETPC());
     }
 
-    exc = mmu_translate(env, addr, 0, asc, &ret, &flags, &tec);
+    exc = mmu_translate(env, addr, MMU_S390_LRA, asc, &ret, &flags, &tec);
     if (exc) {
         cc = 3;
         ret = exc | 0x80000000;