John Snow <js...@redhat.com> writes:
> We're supposed to abort on transfers like this, unless we fill
> Word 125 of our IDENTIFY data with a default transfer size, which
> we don't currently do.
>
> This is an ATA error, not a SCSI/ATAPI one.
> See ATA8-ACS3 sections 7.17.6.49 or 7.21.5.
Reading... yes, that's what the spec says.
> If we don't do this, QEMU will loop forever trying to transfer
> zero bytes, which isn't particularly useful.
Out of curiosity: which loop?
> Signed-off-by: John Snow <js...@redhat.com>
> ---
> hw/ide/atapi.c | 32 +++++++++++++++++++++++++++-----
> hw/ide/core.c | 2 +-
> hw/ide/internal.h | 1 +
> 3 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
> index 79dd167..747f466 100644
> --- a/hw/ide/atapi.c
> +++ b/hw/ide/atapi.c
> @@ -1169,20 +1169,28 @@ enum {
> * 4.1.8)
> */
> CHECK_READY = 0x02,
> +
> + /*
> + * Commands flagged with NONDATA do not in any circumstances return
> + * any data via ide_atapi_cmd_reply. These commands are exempt from
> + * the normal byte_count_limit constraints.
> + * See ATA8-ACS3 "7.21.5 Byte Count Limit"
Aside: that section is bizarre even for ATA.
Missing piece: what tells you which commands are to be flagged NONDATA?
> + */
> + NONDATA = 0x04,
> };
>
> static const struct {
> void (*handler)(IDEState *s, uint8_t *buf);
> int flags;
> } atapi_cmd_table[0x100] = {
> - [ 0x00 ] = { cmd_test_unit_ready, CHECK_READY },
> + [ 0x00 ] = { cmd_test_unit_ready, CHECK_READY | NONDATA },
> [ 0x03 ] = { cmd_request_sense, ALLOW_UA },
> [ 0x12 ] = { cmd_inquiry, ALLOW_UA },
> - [ 0x1b ] = { cmd_start_stop_unit, 0 }, /* [1] */
> - [ 0x1e ] = { cmd_prevent_allow_medium_removal, 0 },
> + [ 0x1b ] = { cmd_start_stop_unit, NONDATA }, /* [1] */
> + [ 0x1e ] = { cmd_prevent_allow_medium_removal, NONDATA },
> [ 0x25 ] = { cmd_read_cdvd_capacity, CHECK_READY },
> [ 0x28 ] = { cmd_read, /* (10) */ CHECK_READY },
> - [ 0x2b ] = { cmd_seek, CHECK_READY },
> + [ 0x2b ] = { cmd_seek, CHECK_READY | NONDATA },
> [ 0x43 ] = { cmd_read_toc_pma_atip, CHECK_READY },
> [ 0x46 ] = { cmd_get_configuration, ALLOW_UA },
> [ 0x4a ] = { cmd_get_event_status_notification, ALLOW_UA },
> @@ -1190,7 +1198,7 @@ static const struct {
> [ 0x5a ] = { cmd_mode_sense, /* (10) */ 0 },
> [ 0xa8 ] = { cmd_read, /* (12) */ CHECK_READY },
> [ 0xad ] = { cmd_read_dvd_structure, CHECK_READY },
> - [ 0xbb ] = { cmd_set_speed, 0 },
> + [ 0xbb ] = { cmd_set_speed, NONDATA },
> [ 0xbd ] = { cmd_mechanism_status, 0 },
> [ 0xbe ] = { cmd_read_cd, CHECK_READY },
> /* [1] handler detects and reports not ready condition itself */
> @@ -1251,6 +1259,20 @@ void ide_atapi_cmd(IDEState *s)
> return;
> }
>
> + /* Nondata commands permit the byte_count_limit to be 0.
> + * If this is a data-transferring PIO command and BCL is 0,
> + * we abort at the /ATA/ level, not the ATAPI level.
> + * See ATA8 ACS3 section 7.17.6.49 and 7.21.5 */
> + if (!(atapi_cmd_table[s->io_buffer[0]].flags & NONDATA)) {
> + /* TODO: Check IDENTIFY data word 125 for default BCL (currently 0)
> */
> + uint16_t byte_count_limit = s->lcyl | (s->hcyl << 8);
You might want to wrap s->lcyl | (s->hcyl << 8) in a helper function
some day. Not in this patch, though.
> + if (!(byte_count_limit || s->atapi_dma)) {
> + /* TODO: Move abort back into core.c and make static inline
> again */
Not sure about the inline part, but that's not this patch's to judge.
> + ide_abort_command(s);
> + return;
> + }
> + }
> +
Let's see whether I can slash through the negations here...
This is for a non-NONDATA command (outer conditional). In other words,
we're expecting data.
Unless either byte_count_limit is non-zero or atapi_dma is true (inner
conditional), we abort the command. In other words: if byte_count_limit
is non-zero, we'll be PIO-ing some data, so we're good. If atapi_dma is
true, we'll be DMA-ing some data, so we're good. Else, no data will be
coming, contradicting our expectation. The command is invalid, and we
abort.
Correct?
> /* Execute the command */
> if (atapi_cmd_table[s->io_buffer[0]].handler) {
> atapi_cmd_table[s->io_buffer[0]].handler(s, buf);
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index 50449ca..28cf535 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -457,7 +457,7 @@ BlockAIOCB *ide_issue_trim(BlockBackend *blk,
> return &iocb->common;
> }
>
> -static inline void ide_abort_command(IDEState *s)
> +void ide_abort_command(IDEState *s)
> {
> ide_transfer_stop(s);
> s->status = READY_STAT | ERR_STAT;
> diff --git a/hw/ide/internal.h b/hw/ide/internal.h
> index 30fdcbc..40e1aa4 100644
> --- a/hw/ide/internal.h
> +++ b/hw/ide/internal.h
> @@ -537,6 +537,7 @@ void ide_set_sector(IDEState *s, int64_t sector_num);
>
> void ide_start_dma(IDEState *s, BlockCompletionFunc *cb);
> void ide_dma_error(IDEState *s);
> +void ide_abort_command(IDEState *s);
>
> void ide_atapi_cmd_ok(IDEState *s);
> void ide_atapi_cmd_error(IDEState *s, int sense_key, int asc);
