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s390/ipl: Fix waiting for virtio processing

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The guest side must not manipulate the index for the used buffers. Instead,
remember the state of the used buffer locally and wait until it has moved.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Cornelia Huck 2013-08-29 17:52:43 +02:00 • committed by Christian Borntraeger
parent abd137a1bc
commit 441ea695f9
2 changed files with 5 additions and 3 deletions
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7
pc-bios/s390-ccw/virtio.c
View file

@ -123,6 +123,7 @@ static void vring_init(struct vring *vr, unsigned int num, void *p,
/* We're running with interrupts off anyways, so don't bother */
vr->used->flags = VRING_USED_F_NO_NOTIFY;
vr->used->idx = 0;
vr->used_idx = 0;
debug_print_addr("init vr", vr);
}
@ -150,8 +151,6 @@ static void vring_send_buf(struct vring *vr, void *p, int len, int flags)
if (!(flags & VRING_DESC_F_NEXT)) {
vr->avail->idx++;
}
vr->used->idx = vr->next_idx;
}
static u64 get_clock(void)
@ -180,7 +179,8 @@ static int vring_wait_reply(struct vring *vr, int timeout)
struct subchannel_id schid = vr->schid;
int r = 0;
while (vr->used->idx == vr->next_idx) {
/* Wait until the used index has moved. */
while (vr->used->idx == vr->used_idx) {
vring_notify(schid);
if (timeout && (get_second() >= target_second)) {
r = 1;
@ -189,6 +189,7 @@ static int vring_wait_reply(struct vring *vr, int timeout)
yield();
}
vr->used_idx = vr->used->idx;
vr->next_idx = 0;
vr->desc[0].len = 0;
vr->desc[0].flags = 0;