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hw/s390x/css: Remove QEMU_PACKED from struct SenseId

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The uint16_t member cu_type of struct SenseId is not naturally aligned,
and since the struct is marked with QEMU_PACKED, this can lead to
unaligned memory accesses - which does not work on architectures like
Sparc. Thus remove the QEMU_PACKED here and rather copy the struct
byte by byte when we do copy_sense_id_to_guest().

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1538036615-32542-3-git-send-email-thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
Thomas Huth 2018-09-27 10:23:34 +02:00 • committed by Cornelia Huck
parent 3b8afb41bc
commit 729315ebca
2 changed files with 23 additions and 17 deletions
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38
hw/s390x/css.c
View file

@ -750,20 +750,25 @@ static void sch_handle_halt_func(SubchDev *sch)
} }
static void copy_sense_id_to_guest(SenseId *dest, SenseId *src) /*
* As the SenseId struct cannot be packed (would cause unaligned accesses), we
* have to copy the individual fields to an unstructured area using the correct
* layout (see SA22-7204-01 "Common I/O-Device Commands").
*/
static void copy_sense_id_to_guest(uint8_t *dest, SenseId *src)
{ {
int i; int i;
dest->reserved = src->reserved; dest[0] = src->reserved;
dest->cu_type = cpu_to_be16(src->cu_type); stw_be_p(dest + 1, src->cu_type);
dest->cu_model = src->cu_model; dest[3] = src->cu_model;
dest->dev_type = cpu_to_be16(src->dev_type); stw_be_p(dest + 4, src->dev_type);
dest->dev_model = src->dev_model; dest[6] = src->dev_model;
dest->unused = src->unused; dest[7] = src->unused;
for (i = 0; i < ARRAY_SIZE(dest->ciw); i++) { for (i = 0; i < ARRAY_SIZE(src->ciw); i++) {
dest->ciw[i].type = src->ciw[i].type; dest[8 + i * 4] = src->ciw[i].type;
dest->ciw[i].command = src->ciw[i].command; dest[9 + i * 4] = src->ciw[i].command;
dest->ciw[i].count = cpu_to_be16(src->ciw[i].count); stw_be_p(dest + 10 + i * 4, src->ciw[i].count);
} }
} }
@ -1044,9 +1049,10 @@ static int css_interpret_ccw(SubchDev *sch, hwaddr ccw_addr,
break; break;
case CCW_CMD_SENSE_ID: case CCW_CMD_SENSE_ID:
{ {
SenseId sense_id; /* According to SA22-7204-01, Sense-ID can store up to 256 bytes */
uint8_t sense_id[256];
copy_sense_id_to_guest(&sense_id, &sch->id); copy_sense_id_to_guest(sense_id, &sch->id);
/* Sense ID information is device specific. */ /* Sense ID information is device specific. */
if (check_len) { if (check_len) {
if (ccw.count != sizeof(sense_id)) { if (ccw.count != sizeof(sense_id)) {
@ -1060,11 +1066,11 @@ static int css_interpret_ccw(SubchDev *sch, hwaddr ccw_addr,
* have enough place to store at least bytes 0-3. * have enough place to store at least bytes 0-3.
*/ */
if (len >= 4) { if (len >= 4) {
sense_id.reserved = 0xff; sense_id[0] = 0xff;
} else { } else {
sense_id.reserved = 0; sense_id[0] = 0;
} }
ccw_dstream_write_buf(&sch->cds, &sense_id, len); ccw_dstream_write_buf(&sch->cds, sense_id, len);
sch->curr_status.scsw.count = ccw_dstream_residual_count(&sch->cds); sch->curr_status.scsw.count = ccw_dstream_residual_count(&sch->cds);
ret = 0; ret = 0;
break; break;

2
include/hw/s390x/css.h
View file

@ -48,7 +48,7 @@ typedef struct SenseId {
uint8_t unused; /* padding byte */ uint8_t unused; /* padding byte */
/* extended part */ /* extended part */
CIW ciw[MAX_CIWS]; /* variable # of CIWs */ CIW ciw[MAX_CIWS]; /* variable # of CIWs */
} QEMU_PACKED SenseId; } SenseId; /* Note: No QEMU_PACKED due to unaligned members */
/* Channel measurements, from linux/drivers/s390/cio/cmf.c. */ /* Channel measurements, from linux/drivers/s390/cio/cmf.c. */
typedef struct CMB { typedef struct CMB {