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, 2 insertions, 2 deletions

diff --git a/exec.c b/exec.c
index 90ac015cb1..ec6e460384 100644
--- a/exec.c
+++ b/exec.c
@@ -3815,8 +3815,8 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
             address_space_write_rom(cpu->cpu_ases[asidx].as, phys_addr,
                                     attrs, buf, l);
         } else {
-            address_space_rw(cpu->cpu_ases[asidx].as, phys_addr, attrs, buf,
-                             l, false);
+            address_space_read(cpu->cpu_ases[asidx].as, phys_addr, attrs, buf,
+                               l);
         }
         len -= l;
         buf += l;