Re: [PATCH v3 2/3] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()

Re: [PATCH v3 2/3] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()

[Jason Wang]

On 2020/10/3 下午6:02, Greg Kurz wrote:
> The open-coded computation of the used size doesn't take the event
> into account when the VIRTIO_RING_F_EVENT_IDX feature is present.
> Fix that by using vhost_get_used_size().
>
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>   drivers/vhost/vhost.c |    3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index c3b49975dc28..9d2c225fb518 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -1519,8 +1519,7 @@ static long vhost_vring_set_addr(struct vhost_dev *d,
>   		/* 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,
> -				sizeof *vq->used +
> -				vq->num * sizeof *vq->used->ring))
> +				       vhost_get_used_size(vq, vq->num)))
>   			return -EINVAL;
>   	}
>   
>
>

Acked-by: Jason Wang <jasowang@redhat.com>


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Re: [PATCH v3 2/3] vhost: Use vhost_get_used_size() in vhost_vring_set_addr()

[Michael S. Tsirkin]

On Sat, Oct 10, 2020 at 10:32:13AM +0800, Jason Wang wrote:
> 
> On 2020/10/3 下午6:02, Greg Kurz wrote:
> > The open-coded computation of the used size doesn't take the event
> > into account when the VIRTIO_RING_F_EVENT_IDX feature is present.
> > Fix that by using vhost_get_used_size().
> > 
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > ---
> >   drivers/vhost/vhost.c |    3 +--
> >   1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > index c3b49975dc28..9d2c225fb518 100644
> > --- a/drivers/vhost/vhost.c
> > +++ b/drivers/vhost/vhost.c
> > @@ -1519,8 +1519,7 @@ static long vhost_vring_set_addr(struct vhost_dev *d,
> >   		/* 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,
> > -				sizeof *vq->used +
> > -				vq->num * sizeof *vq->used->ring))
> > +				       vhost_get_used_size(vq, vq->num)))
> >   			return -EINVAL;
> >   	}
> > 
> > 
> 
> Acked-by: Jason Wang <jasowang@redhat.com>

Linus already merged this, I can't add your ack, sorry!

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Re: [PATCH v3 3/3] vhost: Don't call log_access_ok() when using IOTLB

[Jason Wang]

On 2020/10/3 下午6:02, Greg Kurz wrote:
> 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>


Acked-by: Jason Wang <jasowang@redhat.com>

In the future, we may consider to deprecate log_guest_addr since in any 
case regardless of IOTLB ennoblement we can get GPA from either IOTLB or 
MEM table.

Thanks


> ---
>   drivers/vhost/vhost.c |   23 ++++++++++++++++++-----
>   1 file changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 9d2c225fb518..9ad45e1d27f0 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -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;
>   	}
>   
>
>

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