* Halil Pasic <pa...@linux.vnet.ibm.com> [2017-09-13 13:50:29 +0200]:
> Let's add indirect data addressing support for our virtual channel
> subsystem. This implementation does no bother with any kind of
> prefetching. We simply step trough the IDAL on demand.
>
> Signed-off-by: Halil Pasic <pa...@linux.vnet.ibm.com>
> ---
> hw/s390x/css.c | 109
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 108 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> index 6b0cd8861b..e34b2af4eb 100644
> --- a/hw/s390x/css.c
> +++ b/hw/s390x/css.c
> @@ -819,6 +819,113 @@ incr:
> return 0;
> }
>
> +/* returns values between 1 and bsz, where bs is a power of 2 */
> +static inline uint16_t ida_continuous_left(hwaddr cda, uint64_t bsz)
> +{
> + return bsz - (cda & (bsz - 1));
> +}
> +
> +static inline uint64_t ccw_ida_block_size(uint8_t flags)
> +{
> + return 1ULL << (((flags ^ CDS_F_C64) & (CDS_F_C64 | CDS_F_I2K)) ? 11 :
> 12);
If CDS_F_C64 is set, (flags ^ CDS_F_C64) will be 0, so (1ULL << 11) will
be the result regardless the I2K flag? The logic seems wrong.
I2K is meaningful only when C64 is 1, otherwise it is ignored. The logic
here should be:
if ((flags & CDS_F_C64) && !(flags & CDS_F_I2K)) {
return 1ULL << 12;
}
return 1ULL << 11;
> +}
> +
> +static inline int ida_read_next_idaw(CcwDataStream *cds)
> +{
> + union {uint64_t fmt2; uint32_t fmt1; } idaw;
^
Nit.
> + bool is_fmt2 = cds->flags & CDS_F_C64;
> + int ret;
> + hwaddr idaw_addr;
> +
> + if (is_fmt2) {
> + idaw_addr = cds->cda_orig + sizeof(idaw.fmt2) * cds->at_idaw;
> + if (idaw_addr & 0x07) {
> + return -EINVAL; /* channel program check */
> + }
> + ret = address_space_rw(&address_space_memory, idaw_addr,
> + MEMTXATTRS_UNSPECIFIED, (void *) &idaw.fmt2,
> + sizeof(idaw.fmt2), false);
> + cds->cda = be64_to_cpu(idaw.fmt2);
> + } else {
> + idaw_addr = cds->cda_orig + sizeof(idaw.fmt1) * cds->at_idaw;
> + if (idaw_addr & 0x03) {
?:
(idaw_addr & 0x80000003)
> + return -EINVAL; /* channel program check */
> +
> + }
> + ret = address_space_rw(&address_space_memory, idaw_addr,
> + MEMTXATTRS_UNSPECIFIED, (void *) &idaw.fmt1,
> + sizeof(idaw.fmt1), false);
> + cds->cda = be64_to_cpu(idaw.fmt1);
> + }
> + ++(cds->at_idaw);
> + if (ret != MEMTX_OK) {
> + /* assume inaccessible address */
> + return -EINVAL; /* channel program check */
> +
> + }
> + return 0;
> +}
> +
> +static int ccw_dstream_rw_ida(CcwDataStream *cds, void *buff, int len,
> + CcwDataStreamOp op)
> +{
> + uint64_t bsz = ccw_ida_block_size(cds->flags);
> + int ret = 0;
> + uint16_t cont_left, iter_len;
> +
> + ret = cds_check_len(cds, len);
> + if (ret <= 0) {
> + return ret;
> + }
> + if (!cds->at_idaw) {
> + /* read first idaw */
> + ret = ida_read_next_idaw(cds);
> + if (ret) {
> + goto err;
> + }
> + cont_left = ida_continuous_left(cds->cda, bsz);
> + } else {
> + cont_left = ida_continuous_left(cds->cda, bsz);
> + if (cont_left == bsz) {
> + ret = ida_read_next_idaw(cds);
> + if (ret) {
> + goto err;
> + }
> + if (cds->cda & (bsz - 1)) {
Could move this check into ida_read_next_idaw?
> + ret = -EINVAL; /* channel program check */
> + goto err;
> + }
> + }
> + }
> + do {
> + iter_len = MIN(len, cont_left);
> + if (op != CDS_OP_A) {
> + ret = address_space_rw(&address_space_memory, cds->cda,
> + MEMTXATTRS_UNSPECIFIED, buff, iter_len,
> op);
Ahh, now I recall that explictly defining CDS_OP_R to 0 and CDS_OP_W to
1 in 'struct CcwDataStreamOp' do have a meaning. Does it make sense to
make it more obvious by adding some comment there?
> + if (ret != MEMTX_OK) {
> + /* assume inaccessible address */
> + ret = -EINVAL; /* channel program check */
> + goto err;
> + }
> + }
> + cds->at_byte += iter_len;
> + cds->cda += iter_len;
> + len -= iter_len;
> + if (!len) {
> + break;
> + }
> + ret = ida_read_next_idaw(cds);
> + if (ret) {
> + goto err;
> + }
> + cont_left = bsz;
> + } while (true);
> + return ret;
> +err:
> + cds->flags |= CDS_F_STREAM_BROKEN;
> + return ret;
> +}
> +
> void ccw_dstream_init(CcwDataStream *cds, CCW1 const *ccw, ORB const *orb)
> {
> /*
> @@ -835,7 +942,7 @@ void ccw_dstream_init(CcwDataStream *cds, CCW1 const
> *ccw, ORB const *orb)
> if (!(cds->flags & CDS_F_IDA)) {
> cds->op_handler = ccw_dstream_rw_noflags;
> } else {
> - assert(false);
> + cds->op_handler = ccw_dstream_rw_ida;
> }
> }
>
> --
> 2.13.5
>
Generally, the logic looks fine to me.
--
Dong Jia Shi
