* [Qemu-devel] [PATCH v2 1/1] atapi: abort transfers with 0 byte limits
2015-09-10 23:20 [Qemu-devel] [PATCH v2 0/1] atapi: abort transfers with 0 byte limits John Snow
@ 2015-09-10 23:20 ` John Snow
2015-09-11 3:11 ` Fam Zheng
0 siblings, 1 reply; 4+ messages in thread
From: John Snow @ 2015-09-10 23:20 UTC (permalink / raw)
To: qemu-block; +Cc: kwolf, John Snow, armbru, qemu-devel
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.
If we don't do this, QEMU will loop forever trying to transfer
zero bytes, which isn't particularly useful.
Signed-off-by: John Snow <jsnow@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..a832746 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"
+ */
+ 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);
+ if !(byte_count_limit || s->atapi_dma) {
+ /* TODO: Move abort back into core.c and make static inline again */
+ ide_abort_command(s);
+ return;
+ }
+ }
+
/* 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);
--
2.4.3
^ permalink raw reply related [flat|nested] 4+ messages in thread