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vhost: Don't call log_access_ok() when using IOTLB

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When the IOTLB device is enabled, the log_guest_addr that is passed by
userspace to the VHOST_SET_VRING_ADDR ioctl, and which is then written
to vq->log_addr, is a GIOVA. All writes to this address are translated
by log_user() to writes to an HVA, and then ultimately logged through
the corresponding GPAs in log_write_hva(). No logging will ever occur
with vq->log_addr in this case. It is thus wrong to pass vq->log_addr
and log_guest_addr to log_access_vq() which assumes they are actual
GPAs.

Introduce a new vq_log_used_access_ok() helper that only checks accesses
to the log for the used structure when there isn't an IOTLB device around.

Signed-off-by: Greg Kurz <groug@kaod.org>
Link: https://lore.kernel.org/r/160171933385.284610.10189082586063280867.stgit@bahia.lan
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Greg Kurz 2020-10-03 12:02:13 +02:00 committed by Michael S. Tsirkin
parent 71878fa46c
commit ab5122510b
1 changed files with 18 additions and 5 deletions
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23
drivers/vhost/vhost.c
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@ -1370,6 +1370,20 @@ bool vhost_log_access_ok(struct vhost_dev *dev)
}
EXPORT_SYMBOL_GPL(vhost_log_access_ok);
static bool vq_log_used_access_ok(struct vhost_virtqueue *vq,
void __user *log_base,
bool log_used,
u64 log_addr)
{
/* If an IOTLB device is present, log_addr is a GIOVA that
* will never be logged by log_used(). */
if (vq->iotlb)
return true;
return !log_used || log_access_ok(log_base, log_addr,
vhost_get_used_size(vq, vq->num));
}
/* Verify access for write logging. */
/* Caller should have vq mutex and device mutex */
static bool vq_log_access_ok(struct vhost_virtqueue *vq,
@ -1377,8 +1391,7 @@ static bool vq_log_access_ok(struct vhost_virtqueue *vq,
{
return vq_memory_access_ok(log_base, vq->umem,
vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
(!vq->log_used || log_access_ok(log_base, vq->log_addr,
vhost_get_used_size(vq, vq->num)));
vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr);
}
/* Can we start vq? */
@ -1517,9 +1530,9 @@ static long vhost_vring_set_addr(struct vhost_dev *d,
return -EINVAL;
/* Also validate log access for used ring if enabled. */
if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
!log_access_ok(vq->log_base, a.log_guest_addr,
vhost_get_used_size(vq, vq->num)))
if (!vq_log_used_access_ok(vq, vq->log_base,
a.flags & (0x1 << VHOST_VRING_F_LOG),
a.log_guest_addr))
return -EINVAL;
}