Avoid address_space_rw() with a constant is_write argument

The address_space_rw() function allows either reads or writes
depending on the is_write argument passed to it; this is useful
when the direction of the access is determined programmatically
(as for instance when handling the KVM_EXIT_MMIO exit reason).
Under the hood it just calls either address_space_write() or
address_space_read_full().

We also use it a lot with a constant is_write argument, though,
which has two issues:
 * when reading "address_space_rw(..., 1)" this is less
   immediately clear to the reader as being a write than
   "address_space_write(...)"
 * calling address_space_rw() bypasses the optimization
   in address_space_read() that fast-paths reads of a
   fixed length

This commit was produced with the included Coccinelle script
scripts/coccinelle/exec_rw_const.cocci.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <20200218112457.22712-1-peter.maydell@linaro.org>
[PMD: Update macvm_set_cr0() reported by Laurent Vivier]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index f27f8c45a5..5d8e08667e 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -874,18 +874,18 @@ static inline int ida_read_next_idaw(CcwDataStream *cds)
         if (idaw_addr & 0x07 || !cds_ccw_addrs_ok(idaw_addr, 0, ccw_fmt1)) {
             return -EINVAL; /* channel program check */
         }
-        ret = address_space_rw(&address_space_memory, idaw_addr,
-                               MEMTXATTRS_UNSPECIFIED, &idaw.fmt2,
-                               sizeof(idaw.fmt2), false);
+        ret = address_space_read(&address_space_memory, idaw_addr,
+                                 MEMTXATTRS_UNSPECIFIED, &idaw.fmt2,
+                                 sizeof(idaw.fmt2));
         cds->cda = be64_to_cpu(idaw.fmt2);
     } else {
         idaw_addr = cds->cda_orig + sizeof(idaw.fmt1) * cds->at_idaw;
         if (idaw_addr & 0x03 || !cds_ccw_addrs_ok(idaw_addr, 0, ccw_fmt1)) {
             return -EINVAL; /* channel program check */
         }
-        ret = address_space_rw(&address_space_memory, idaw_addr,
-                               MEMTXATTRS_UNSPECIFIED, &idaw.fmt1,
-                               sizeof(idaw.fmt1), false);
+        ret = address_space_read(&address_space_memory, idaw_addr,
+                                 MEMTXATTRS_UNSPECIFIED, &idaw.fmt1,
+                                 sizeof(idaw.fmt1));
         cds->cda = be64_to_cpu(idaw.fmt1);
         if (cds->cda & 0x80000000) {
             return -EINVAL; /* channel program check */