[Qemu-devel] [RFC PATCH] target-s390x: Implement mvcos instruction

[Miroslav Benes <mbenes@suse.cz>]

Implement MVCOS instruction, which the Linux kernel uses in user access
functions.

Signed-off-by: Miroslav Benes <mbenes@suse.cz>
---
I tried to do my best to follow the specification but it is quite
possible that I got something wrong because of my lack of
understanding. Especially I am not sure about all those bit ops :/.

Anyway, there is one piece missing. The actual use of keys and
address-space-control during the move. I used fast_memmove, but
it is not correct. Is there a helper which I could use? I looked at
other instructions which should implement access control, but there were
silently ignore it :).

 target/s390x/helper.h      |  1 +
 target/s390x/insn-data.def |  2 ++
 target/s390x/mem_helper.c  | 80 ++++++++++++++++++++++++++++++++++++++++++++++
 target/s390x/translate.c   | 12 +++++++
 4 files changed, 95 insertions(+)

diff --git a/target/s390x/helper.h b/target/s390x/helper.h
index 9102071d0aa4..bc5dfccc3d7e 100644
--- a/target/s390x/helper.h
+++ b/target/s390x/helper.h
@@ -104,6 +104,7 @@ DEF_HELPER_FLAGS_2(iske, TCG_CALL_NO_RWG_SE, i64, env, i64)
 DEF_HELPER_FLAGS_3(sske, TCG_CALL_NO_RWG, void, env, i64, i64)
 DEF_HELPER_FLAGS_2(rrbe, TCG_CALL_NO_RWG, i32, env, i64)
 DEF_HELPER_3(csp, i32, env, i32, i64)
+DEF_HELPER_5(mvcos, i32, env, i64, i64, i64, i64)
 DEF_HELPER_4(mvcs, i32, env, i64, i64, i64)
 DEF_HELPER_4(mvcp, i32, env, i64, i64, i64)
 DEF_HELPER_4(sigp, i32, env, i64, i32, i64)
diff --git a/target/s390x/insn-data.def b/target/s390x/insn-data.def
index 075ff597c3de..a1e6d735d090 100644
--- a/target/s390x/insn-data.def
+++ b/target/s390x/insn-data.def
@@ -854,6 +854,8 @@
 /* LOAD USING REAL ADDRESS */
     C(0xb24b, LURA,    RRE,   Z,   0, r2, new, r1_32, lura, 0)
     C(0xb905, LURAG,   RRE,   Z,   0, r2, r1, 0, lurag, 0)
+/* MOVE WITH OPTIONAL SPECIFICATION */
+    C(0xc800, MVCOS,   SSF,   MVCOS, la1, a2, 0, 0, mvcos, 0)
 /* MOVE TO PRIMARY */
     C(0xda00, MVCP,    SS_d,  Z,   la1, a2, 0, 0, mvcp, 0)
 /* MOVE TO SECONDARY */
diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 675aba2e44d4..ca8f7c49250c 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -1089,6 +1089,86 @@ uint32_t HELPER(mvcp)(CPUS390XState *env, uint64_t l, uint64_t a1, uint64_t a2)
     return cc;
 }
 
+uint32_t HELPER(mvcos)(CPUS390XState *env, uint64_t r0, uint64_t dest,
+                       uint64_t src, uint64_t len)
+{
+    int cc;
+    int key1, as1, abit1, kbit1;
+    int key2, as2, abit2, kbit2;
+
+    HELPER_LOG("%s dest %" PRIx64 ", src %" PRIx64 ", len %" PRIx64 "\n",
+               __func__, dest, src, len);
+
+    /* check DAT */
+    if (!(env->psw.mask & PSW_MASK_DAT)) {
+        program_interrupt(env, PGM_SPECIAL_OP, 2);
+    }
+
+    /* access control for the first operand */
+    abit1 = (r0 & 0x0010000ULL) >> 16;
+    kbit1 = (r0 & 0x0020000ULL) >> 17;
+    as1 = (r0 & 0x00c00000ULL) >> 22;
+    key1 = (r0 & 0xf0000000ULL) >> 28;
+
+    if (!kbit1) {
+        key1 = (env->psw.mask & PSW_MASK_KEY) >> (PSW_SHIFT_KEY - 4);
+    }
+
+    if (!abit1) {
+        as1 = (env->psw.mask & PSW_MASK_ASC) >> 46;
+    }
+
+    /*
+     * abit1 is set, as1 designates the home-space mode, psw is in the problem
+     * state.
+     * */
+    if (abit1 && (as1 == 3) && (env->psw.mask & PSW_MASK_PSTATE)) {
+        program_interrupt(env, PGM_SPECIAL_OP, 2);
+    }
+
+    /* access control for the second operand */
+    abit2 = (r0 & 0x0010000ULL);
+    kbit2 = (r0 & 0x0020000ULL) >> 1;
+    as2 = (r0 & 0x00c00000ULL) >> 6;
+    key2 = (r0 & 0xf0000000ULL) >> 12;
+
+    if (!kbit2) {
+        key2 = (env->psw.mask & PSW_MASK_KEY) >> (PSW_SHIFT_KEY - 4);
+    }
+
+    if (!abit2) {
+        as2 = (env->psw.mask & PSW_MASK_ASC) >> 46;
+    }
+
+    /*
+     * Secondary-space control bit is zero (bit 37 of r0) and either as
+     * designates secondary-space mode.
+     */
+    if (!(r0 & 0x2000000000ULL) && (as1 == 2 || as2 == 2)) {
+        program_interrupt(env, PGM_SPECIAL_OP, 2);
+    }
+
+    /* psw is in the problem state and either key is invalid */
+    if ((env->psw.mask & PSW_MASK_PSTATE) &&
+        (!(env->cregs[3] & (1 << (31 - key1))) ||
+         !(env->cregs[3] & (1 << (31 - key2))))) {
+        program_interrupt(env, PGM_PRIVILEGED, 2);
+    }
+
+    if (len <= 4096) {
+        cc = 0;
+    } else {
+        cc = 3;
+        len = 4096;
+    }
+
+    /* move */
+    /* XXX use keys and as during the move */
+    fast_memmove(env, dest, src, len);
+
+    return cc;
+}
+
 /* invalidate pte */
 void HELPER(ipte)(CPUS390XState *env, uint64_t pte_addr, uint64_t vaddr)
 {
diff --git a/target/s390x/translate.c b/target/s390x/translate.c
index 01c62176bf70..ac90b758d312 100644
--- a/target/s390x/translate.c
+++ b/target/s390x/translate.c
@@ -1194,6 +1194,7 @@ typedef enum DisasFacility {
     FAC_SCF,                /* store clock fast */
     FAC_SFLE,               /* store facility list extended */
     FAC_ILA,                /* interlocked access facility 1 */
+    FAC_MVCOS,              /* move-with-optional-specification */
 } DisasFacility;
 
 struct DisasInsn {
@@ -2877,6 +2878,17 @@ static ExitStatus op_mvcs(DisasContext *s, DisasOps *o)
     set_cc_static(s);
     return NO_EXIT;
 }
+
+static ExitStatus op_mvcos(DisasContext *s, DisasOps *o)
+{
+    int r3 = get_field(s->fields, r3);
+
+    check_privileged(s);
+    potential_page_fault(s);
+    gen_helper_mvcos(cc_op, cpu_env, regs[0], o->addr1, o->in2, regs[r3]);
+    set_cc_static(s);
+    return NO_EXIT;
+}
 #endif
 
 static ExitStatus op_mvpg(DisasContext *s, DisasOps *o)
-- 
2.12.0