[Qemu-devel] [PATCH v2 04/28] s390x/tcg: MVCL: Process max 2k bytes at a time

[David Hildenbrand]

Process max 2k bytes at a time, writing back registers between the
accesses. The instruction is interruptible.
    "For operands longer than 2K bytes, access exceptions are not
    recognized for locations more than 2K bytes beyond the current location
    being processed."

MVCL handling is quite different than MVCLE/MVCLU handling, so split up
the handlers.

We'll deal with fast_memmove() and fast_memset() not probing
reads/writes properly later. Also, we'll defer interrupt handling, as
that will require more thought, add a TODO for that.

Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 target/s390x/mem_helper.c | 44 +++++++++++++++++++++++++++++++++------
 1 file changed, 38 insertions(+), 6 deletions(-)

diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 2361ed6d54..2e22c183bd 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -799,19 +799,51 @@ uint32_t HELPER(mvcl)(CPUS390XState *env, uint32_t r1, 
uint32_t r2)
     uint64_t srclen = env->regs[r2 + 1] & 0xffffff;
     uint64_t src = get_address(env, r2);
     uint8_t pad = env->regs[r2 + 1] >> 24;
-    uint32_t cc;
+    uint32_t cc, cur_len;
 
     if (is_destructive_overlap(env, dest, src, MIN(srclen, destlen))) {
         cc = 3;
+    } else if (srclen == destlen) {
+        cc = 0;
+    } else if (destlen < srclen) {
+        cc = 1;
     } else {
-        cc = do_mvcl(env, &dest, &destlen, &src, &srclen, pad, 1, ra);
+        cc = 2;
     }
 
-    env->regs[r1 + 1] = deposit64(env->regs[r1 + 1], 0, 24, destlen);
-    env->regs[r2 + 1] = deposit64(env->regs[r2 + 1], 0, 24, srclen);
-    set_address_zero(env, r1, dest);
-    set_address_zero(env, r2, src);
+    /* We might have to zero-out some bits even if there was no action. */
+    if (unlikely(!destlen || cc == 3)) {
+        set_address_zero(env, r2, src);
+        set_address_zero(env, r1, dest);
+        return cc;
+    } else if (!srclen) {
+        set_address_zero(env, r2, src);
+    }
 
+    /*
+     * Only perform one type of type of operation (move/pad) in one step.
+     * Process up to 2k bytes.
+     */
+    while (destlen) {
+        cur_len = MIN(destlen, 2048);
+        if (!srclen) {
+            fast_memset(env, dest, pad, cur_len, ra);
+        } else {
+            cur_len = MIN(cur_len, srclen);
+
+            fast_memmove(env, dest, src, cur_len, ra);
+            src = wrap_address(env, src + cur_len);
+            srclen -= cur_len;
+            env->regs[r2 + 1] = deposit64(env->regs[r2 + 1], 0, 24, srclen);
+            set_address_zero(env, r2, src);
+        }
+        dest = wrap_address(env, dest + cur_len);
+        destlen -= cur_len;
+        env->regs[r1 + 1] = deposit64(env->regs[r1 + 1], 0, 24, destlen);
+        set_address_zero(env, r1, dest);
+
+        /* TODO: Deliver interrupts. */
+    }
     return cc;
 }
 
-- 
2.21.0