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, 4 insertions, 7 deletions

diff --git a/hw/dma/xlnx-zdma.c b/hw/dma/xlnx-zdma.c
index 683abbe53f..1c1b142293 100644
--- a/hw/dma/xlnx-zdma.c
+++ b/hw/dma/xlnx-zdma.c
@@ -311,8 +311,7 @@ static bool zdma_load_descriptor(XlnxZDMA *s, uint64_t addr, void *buf)
         return false;
     }
 
-    address_space_rw(s->dma_as, addr, s->attr,
-                     buf, sizeof(XlnxZDMADescr), false);
+    address_space_read(s->dma_as, addr, s->attr, buf, sizeof(XlnxZDMADescr));
     return true;
 }
 
@@ -364,7 +363,7 @@ static uint64_t zdma_update_descr_addr(XlnxZDMA *s, bool type,
     } else {
         addr = zdma_get_regaddr64(s, basereg);
         addr += sizeof(s->dsc_dst);
-        address_space_rw(s->dma_as, addr, s->attr, &next, 8, false);
+        address_space_read(s->dma_as, addr, s->attr, &next, 8);
         zdma_put_regaddr64(s, basereg, next);
     }
     return next;
@@ -416,8 +415,7 @@ static void zdma_write_dst(XlnxZDMA *s, uint8_t *buf, uint32_t len)
             }
         }
 
-        address_space_rw(s->dma_as, s->dsc_dst.addr, s->attr, buf, dlen,
-                         true);
+        address_space_write(s->dma_as, s->dsc_dst.addr, s->attr, buf, dlen);
         if (burst_type == AXI_BURST_INCR) {
             s->dsc_dst.addr += dlen;
         }
@@ -493,8 +491,7 @@ static void zdma_process_descr(XlnxZDMA *s)
                 len = s->cfg.bus_width / 8;
             }
         } else {
-            address_space_rw(s->dma_as, src_addr, s->attr, s->buf, len,
-                             false);
+            address_space_read(s->dma_as, src_addr, s->attr, s->buf, len);
             if (burst_type == AXI_BURST_INCR) {
                 src_addr += len;
             }