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Avoid address_space_rw() with a constant is_write argument

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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>
This commit is contained in:
Peter Maydell 2020-02-18 11:24:57 +00:00 • committed by Philippe Mathieu-Daudé
parent 1ccda935d4
commit 19f7034773
13 changed files with 119 additions and 107 deletions
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12
hw/s390x/css.c
View file

@ -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 */