[ Upstream commit c2c63310 ]

There's a potential race in xennet_remove(); this is what the driver is
doing upon unregistering a network device:

  1. state = read bus state
  2. if state is not "Closed":
  3.    request to set state to "Closing"
  4.    wait for state to be set to "Closing"
  5.    request to set state to "Closed"
  6.    wait for state to be set to "Closed"

If the state changes to "Closed" immediately after step 1 we are stuck
forever in step 4, because the state will never go back from "Closed" to
"Closing".

Make sure to check also for state == "Closed" in step 4 to prevent the
deadlock.

Also add a 5 sec timeout any time we wait for the bus state to change,
to avoid getting stuck forever in wait_event().

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit a761129e ]

xennet_fill_frags() uses ~0U as return value when the sk_buff is not able
to cache extra fragments. This is incorrect because the return type of
xennet_fill_frags() is RING_IDX and 0xffffffff is an expected value for
ring buffer index.

In the situation when the rsp_cons is approaching 0xffffffff, the return
value of xennet_fill_frags() may become 0xffffffff which xennet_poll() (the
caller) would regard as error. As a result, queue->rx.rsp_cons is set
incorrectly because it is updated only when there is error. If there is no
error, xennet_poll() would be responsible to update queue->rx.rsp_cons.
Finally, queue->rx.rsp_cons would point to the rx ring buffer entries whose
queue->rx_skbs[i] and queue->grant_rx_ref[i] are already cleared to NULL.
This leads to NULL pointer access in the next iteration to process rx ring
buffer entries.

The symptom is similar to the one fixed in
commit 00b36850 ("xen-netfront: do not assume sk_buff_head list is
empty in error handling").

This patch changes the return type of xennet_fill_frags() to indicate
whether it is successful or failed. The queue->rx.rsp_cons will be
always updated inside this function.

Fixes: ad4f15dc ("xen/netfront: don't bug in case of too many frags")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 00b36850 ]

When skb_shinfo(skb) is not able to cache extra fragment (that is,
skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS), xennet_fill_frags() assumes
the sk_buff_head list is already empty. As a result, cons is increased only
by 1 and returns to error handling path in xennet_poll().

However, if the sk_buff_head list is not empty, queue->rx.rsp_cons may be
set incorrectly. That is, queue->rx.rsp_cons would point to the rx ring
buffer entries whose queue->rx_skbs[i] and queue->grant_rx_ref[i] are
already cleared to NULL. This leads to NULL pointer access in the next
iteration to process rx ring buffer entries.

Below is how xennet_poll() does error handling. All remaining entries in
tmpq are accounted to queue->rx.rsp_cons without assuming how many
outstanding skbs are remained in the list.

 985 static int xennet_poll(struct napi_struct *napi, int budget)
... ...
1032           if (unlikely(xennet_set_skb_gso(skb, gso))) {
1033                   __skb_queue_head(&tmpq, skb);
1034                   queue->rx.rsp_cons += skb_queue_len(&tmpq);
1035                   goto err;
1036           }

It is better to always have the error handling in the same way.

Fixes: ad4f15dc ("xen/netfront: don't bug in case of too many frags")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit d81c5054 ]

At least old Xen net backends seem to send frags with no real data
sometimes. In case such a fragment happens to occur with the frag limit
already reached the frontend will BUG currently even if this situation
is easily recoverable.

Modify the BUG_ON() condition accordingly.

Tested-by: Dietmar Hahn <dietmar.hahn@ts.fujitsu.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit cb257783 ]

Fixes: f599c64f ("xen-netfront: Fix race between device setup and open")
Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 45c8184c ]

Update the features after calling register_netdev() otherwise the
device features are not set up correctly and it not possible to change
the MTU of the device. After this change, the features reported by
ethtool match the device's features before the commit which introduced
the issue and it is possible to change the device's MTU.

Fixes: f599c64f ("xen-netfront: Fix race between device setup and open")
Reported-by: Liam Shepherd <liam@dancer.es>
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

commit ad4f15dc upstream.

Commit 57f230ab ("xen/netfront: raise max number of slots in
xennet_get_responses()") raised the max number of allowed slots by one.
This seems to be problematic in some configurations with netback using
a larger MAX_SKB_FRAGS value (e.g. old Linux kernel with MAX_SKB_FRAGS
defined as 18 instead of nowadays 17).

Instead of BUG_ON() in this case just fall back to retransmission.

Fixes: 57f230ab ("xen/netfront: raise max number of slots in xennet_get_responses()")
Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 8edfe2e9 upstream.

Commit 822fb18a ("xen-netfront: wait xenbus state change when load
module manually") added a new wait queue to wait on for a state change
when the module is loaded manually. Unfortunately there is no wakeup
anywhere to stop that waiting.

Instead of introducing a new wait queue rename the existing
module_unload_q to module_wq and use it for both purposes (loading and
unloading).

As any state change of the backend might be intended to stop waiting
do the wake_up_all() in any case when netback_changed() is called.

Fixes: 822fb18a ("xen-netfront: wait xenbus state change when load module manually")
Cc: <stable@vger.kernel.org> #4.18
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 21f2706b ]

There is a call trace generated after commit 2d408c0d(
xen-netfront: fix queue name setting). There is no 'device/vif/xx-q0-tx' file found
under /proc/irq/xx/.

This patch only picks up device type and id as its name.

With the patch, now /proc/interrupts looks like below and the warning message gone:
 70:         21          0          0          0   xen-dyn    -event     vif0-q0-tx
 71:         15          0          0          0   xen-dyn    -event     vif0-q0-rx
 72:         14          0          0          0   xen-dyn    -event     vif0-q1-tx
 73:         33          0          0          0   xen-dyn    -event     vif0-q1-rx
 74:         12          0          0          0   xen-dyn    -event     vif0-q2-tx
 75:         24          0          0          0   xen-dyn    -event     vif0-q2-rx
 76:         19          0          0          0   xen-dyn    -event     vif0-q3-tx
 77:         21          0          0          0   xen-dyn    -event     vif0-q3-rx

Below is call trace information without this patch:

name 'device/vif/0-q0-tx'
WARNING: CPU: 2 PID: 37 at fs/proc/generic.c:174 __xlate_proc_name+0x85/0xa0
RIP: 0010:__xlate_proc_name+0x85/0xa0
RSP: 0018:ffffb85c40473c18 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000000006
RDX: 0000000000000007 RSI: 0000000000000096 RDI: ffff984c7f516930
RBP: ffffb85c40473cb8 R08: 000000000000002c R09: 0000000000000229
R10: 0000000000000000 R11: 0000000000000001 R12: ffffb85c40473c98
R13: ffffb85c40473cb8 R14: ffffb85c40473c50 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff984c7f500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f69b6899038 CR3: 000000001c20a006 CR4: 00000000001606e0
Call Trace:
__proc_create+0x45/0x230
? snprintf+0x49/0x60
proc_mkdir_data+0x35/0x90
register_handler_proc+0xef/0x110
? proc_register+0xfc/0x110
? proc_create_data+0x70/0xb0
__setup_irq+0x39b/0x660
? request_threaded_irq+0xad/0x160
request_threaded_irq+0xf5/0x160
? xennet_tx_buf_gc+0x1d0/0x1d0 [xen_netfront]
bind_evtchn_to_irqhandler+0x3d/0x70
? xenbus_alloc_evtchn+0x41/0xa0
netback_changed+0xa46/0xcda [xen_netfront]
? find_watch+0x40/0x40
xenwatch_thread+0xc5/0x160
? finish_wait+0x80/0x80
kthread+0x112/0x130
? kthread_create_worker_on_cpu+0x70/0x70
ret_from_fork+0x35/0x40
Code: 81 5c 00 48 85 c0 75 cc 5b 49 89 2e 31 c0 5d 4d 89 3c 24 41 5c 41 5d 41 5e 41 5f c3 4c 89 ee 48 c7 c7 40 4f 0e b4 e8 65 ea d8 ff <0f> 0b b8 fe ff ff ff 5b 5d 41 5c 41 5d 41 5e 41 5f c3 66 0f 1f
---[ end trace 650e5561b0caab3a ]---

Signed-off-by: Xiao Liang <xiliang@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 2d408c0d ]

Commit f599c64f ("xen-netfront: Fix race between device setup and
open") changed the initialization order: xennet_create_queues() now
happens before we do register_netdev() so using netdev->name in
xennet_init_queue() is incorrect, we end up with the following in
/proc/interrupts:

 60:        139          0   xen-dyn    -event     eth%d-q0-tx
 61:        265          0   xen-dyn    -event     eth%d-q0-rx
 62:        234          0   xen-dyn    -event     eth%d-q1-tx
 63:          1          0   xen-dyn    -event     eth%d-q1-rx

and this looks ugly. Actually, using early netdev name (even when it's
already set) is also not ideal: nowadays we tend to rename eth devices
and queue name may end up not corresponding to the netdev name.

Use nodename from xenbus device for queue naming: this can't change in VM's
lifetime. Now /proc/interrupts looks like

 62:        202          0   xen-dyn    -event     device/vif/0-q0-tx
 63:        317          0   xen-dyn    -event     device/vif/0-q0-rx
 64:        262          0   xen-dyn    -event     device/vif/0-q1-tx
 65:         17          0   xen-dyn    -event     device/vif/0-q1-rx

Fixes: f599c64f ("xen-netfront: Fix race between device setup and open")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit d472b3a6 upstream.

skb_shinfo() can change when calling __pskb_pull_tail(): Don't cache
its return value.

Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 822fb18a ]

When loading module manually, after call xenbus_switch_state to initializes
the state of the netfront device, the driver state did not change so fast
that may lead no dev created in latest kernel. This patch adds wait to make
sure xenbus knows the driver is not in closed/unknown state.

Current state:
[vm]# ethtool eth0
Settings for eth0:
	Link detected: yes
[vm]# modprobe -r xen_netfront
[vm]# modprobe  xen_netfront
[vm]# ethtool eth0
Settings for eth0:
Cannot get device settings: No such device
Cannot get wake-on-lan settings: No such device
Cannot get message level: No such device
Cannot get link status: No such device
No data available

With the patch installed.
[vm]# ethtool eth0
Settings for eth0:
	Link detected: yes
[vm]# modprobe -r xen_netfront
[vm]# modprobe xen_netfront
[vm]# ethtool eth0
Settings for eth0:
	Link detected: yes

Signed-off-by: Xiao Liang <xiliang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 57f230ab ]

The max number of slots used in xennet_get_responses() is set to
MAX_SKB_FRAGS + (rx->status <= RX_COPY_THRESHOLD).

In old kernel-xen MAX_SKB_FRAGS was 18, while nowadays it is 17. This
difference is resulting in frequent messages "too many slots" and a
reduced network throughput for some workloads (factor 10 below that of
a kernel-xen based guest).

Replacing MAX_SKB_FRAGS by XEN_NETIF_NR_SLOTS_MIN for calculation of
the max number of slots to use solves that problem (tests showed no
more messages "too many slots" and throughput was as high as with the
kernel-xen based guest system).

Replace MAX_SKB_FRAGS-2 by XEN_NETIF_NR_SLOTS_MIN-1 in
netfront_tx_slot_available() for making it clearer what is really being
tested without actually modifying the tested value.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit f599c64f ]

When a netfront device is set up it registers a netdev fairly early on,
before it has set up the queues and is actually usable. A userspace tool
like NetworkManager will immediately try to open it and access its state
as soon as it appears. The bug can be reproduced by hotplugging VIFs
until the VM runs out of grant refs. It registers the netdev but fails
to set up any queues (since there are no more grant refs). In the
meantime, NetworkManager opens the device and the kernel crashes trying
to access the queues (of which there are none).

Fix this in two ways:
* For initial setup, register the netdev much later, after the queues
are setup. This avoids the race entirely.
* During a suspend/resume cycle, the frontend reconnects to the backend
and the queues are recreated. It is possible (though highly unlikely) to
race with something opening the device and accessing the queues after
they have been destroyed but before they have been recreated. Extend the
region covered by the rtnl semaphore to protect against this race. There
is a possibility that we fail to recreate the queues so check for this
in the open function.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit c2d2e673 upstream.

A toolstack may delete the vif frontend and backend xenstore entries
while xen-netfront is in the removal code path.  In that case, the
checks for xenbus_read_driver_state would return XenbusStateUnknown, and
xennet_remove would hang indefinitely.  This hang prevents system
shutdown.

xennet_remove must be able to handle XenbusStateUnknown, and
netback_changed must also wake up the wake_queue for that state as well.

Fixes: 5b5971df ("xen-netfront: remove warning when unloading module")

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Cc: Eduardo Otubo <otubo@redhat.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit b707fda2 ]

When loading the module after unloading it, the network interface would
not be enabled and thus wouldn't have a backend counterpart and unable
to be used by the guest.

The guest would face errors like:

  [root@guest ~]# ethtool -i eth0
  Cannot get driver information: No such device

  [root@guest ~]# ifconfig eth0
  eth0: error fetching interface information: Device not found

This patch initializes the state of the netfront device whenever it is
loaded manually, this state would communicate the netback to create its
device and establish the connection between them.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 5b5971df ]

v2:
 * Replace busy wait with wait_event()/wake_up_all()
 * Cannot garantee that at the time xennet_remove is called, the
   xen_netback state will not be XenbusStateClosed, so added a
   condition for that
 * There's a small chance for the xen_netback state is
   XenbusStateUnknown by the time the xen_netfront switches to Closed,
   so added a condition for that.

When unloading module xen_netfront from guest, dmesg would output
warning messages like below:

  [  105.236836] xen:grant_table: WARNING: g.e. 0x903 still in use!
  [  105.236839] deferring g.e. 0x903 (pfn 0x35805)

This problem relies on netfront and netback being out of sync. By the time
netfront revokes the g.e.'s netback didn't have enough time to free all of
them, hence displaying the warnings on dmesg.

The trick here is to make netfront to wait until netback frees all the g.e.'s
and only then continue to cleanup for the module removal, and this is done by
manipulating both device states.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>
Acked-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit d86b5672 upstream.

Unavoidable crashes in netfront_resume() and netback_changed() after a
previous fail in talk_to_netback() (e.g. when we fail to read MAC from
xenstore) were discovered. The failure path in talk_to_netback() does
unregister/free for netdev but we don't reset drvdata and we try accessing
it after resume.

Fix the bug by removing the whole xen device completely with
device_unregister(), this guarantees we won't have any calls into netfront
after a failure.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit e2e004ac ]

This fixes a crash when running out of grant refs when creating many
queues across many netdevs.

* If creating queues fails (i.e. there are no grant refs available),
call xenbus_dev_fatal() to ensure that the xenbus device is set to the
closed state.
* If no queues are created, don't call xennet_disconnect_backend as
netdev->real_num_tx_queues will not have been set correctly.
* If setup_netfront() fails, ensure that all the queues created are
cleaned up, not just those that have been set up.
* If any queues were set up and an error occurs, call
xennet_destroy_queues() to clean up the napi context.
* If any fatal error occurs, unregister and destroy the netdev to avoid
leaving around a half setup network device.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 538d9291 upstream.

The commit 90c311b0 ("xen-netfront: Fix Rx stall during network
stress and OOM") caused the refill timer to be triggerred almost on
all invocations of xennet_alloc_rx_buffers for certain workloads.
This reworks the fix by reverting to the old behaviour and taking into
consideration the skb allocation failure. Refill timer is now triggered
on insufficient requests or skb allocation failure.

Signed-off-by: Vineeth Remanan Pillai <vineethp@amazon.com>
Fixes: 90c311b0 (xen-netfront: Fix Rx stall during network stress and OOM)
Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Eduardo Valentin <eduval@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 90c311b0 ]

During an OOM scenario, request slots could not be created as skb
allocation fails. So the netback cannot pass in packets and netfront
wrongly assumes that there is no more work to be done and it disables
polling. This causes Rx to stall.

The issue is with the retry logic which schedules the timer if the
created slots are less than NET_RX_SLOTS_MIN. The count of new request
slots to be pushed are calculated as a difference between new req_prod
and rsp_cons which could be more than the actual slots, if there are
unconsumed responses.

The fix is to calculate the count of newly created slots as the
difference between new req_prod and old req_prod.

Signed-off-by: Vineeth Remanan Pillai <vineethp@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 74470954 upstream.

rx_refill_timer should be deleted as soon as we disconnect from the
backend since otherwise it is possible for the timer to go off before
we get to xennet_destroy_queues(). If this happens we may dereference
queue->rx.sring which is set to NULL in xennet_disconnect_backend().

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

IS_ERR_VALUE() in commit 87557efc
("xen-netfront: do not cast grant table reference to signed short") would
not return true for error code unless we cast ref first to type int.

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

While grant reference is of type uint32_t, xen-netfront erroneously casts
it to signed short in BUG_ON().

This would lead to the xen domU panic during boot-up or migration when it
is attached with lots of paravirtual devices.

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Small packet loss is reported on complex multi host network configurations
including tunnels, NAT, ... My investigation led me to the following check
in netback which drops packets:

        if (unlikely(txreq.size < ETH_HLEN)) {
                netdev_err(queue->vif->dev,
                           "Bad packet size: %d\n", txreq.size);
                xenvif_tx_err(queue, &txreq, extra_count, idx);
                break;
        }

But this check itself is legitimate. SKBs consist of a linear part (which
has to have the ethernet header) and (optionally) a number of frags.
Netfront transmits the head of the linear part up to the page boundary
as the first request and all the rest becomes frags so when we're
reconstructing the SKB in netback we can't distinguish between original
frags and the 'tail' of the linear part. The first SKB needs to be at
least ETH_HLEN size. So in case we have an SKB with its linear part
starting too close to the page boundary the packet is lost.

I see two ways to fix the issue:
- Change the 'wire' protocol between netfront and netback to start keeping
  the original SKB structure. We'll have to add a flag indicating the fact
  that the particular request is a part of the original linear part and not
  a frag. We'll need to know the length of the linear part to pre-allocate
  memory.
- Avoid transmitting SKBs with linear parts starting too close to the page
  boundary. That seems preferable short-term and shouldn't bring
  significant performance degradation as such packets are rare. That's what
  this patch is trying to achieve with skb_copy().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Trying to batch Tx response events results in poor performance because
this delays freeing the transmitted skbs.

Instead use the standard RING_FINAL_CHECK_FOR_RESPONSES() macro to be
notified once the next Tx response is placed on the ring.

Signed-off-by: Malcolm Crossley <malcolm.crossley@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The PV network protocol is using 4KB page granularity. The goal of this
patch is to allow a Linux using 64KB page granularity using network
device on a non-modified Xen.

It's only necessary to adapt the ring size and break skb data in small
chunk of 4KB. The rest of the code is relying on the grant table code.

Note that we allocate a Linux page for each rx skb but only the first
4KB is used. We may improve the memory usage by extending the size of
the rx skb.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

Sometimes xennet_create_queues() may failed to created all requested
queues, we need to update num_queues to real created to avoid NULL
pointer dereference.

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

If netfront connects with two (or more) queues and then reconnects with
only one queue it fails to delete or rewrite the multi-queue-num-queues
key and netback will try to use the wrong number of queues.

Always write the num-queues field if the backend has multi-queue support.

Signed-off-by: Chas Williams <3chas3@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Originally that parameter was always reset to num_online_cpus during
module initialisation, which renders it useless.

The fix is to only set max_queues to num_online_cpus when user has not
provided a value.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Tested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN
is meant, I suspect this is because the first support for Xen was for
PV. This resulted in some misimplementation of helpers on ARM and
confused developers about the expected behavior.

For instance, with pfn_to_mfn, we expect to get an MFN based on the name.
Although, if we look at the implementation on x86, it's returning a GFN.

For clarity and avoid new confusion, replace any reference to mfn with
gfn in any helpers used by PV drivers. The x86 code will still keep some
reference of pfn_to_mfn which may be used by all kind of guests
No changes as been made in the hypercall field, even
though they may be invalid, in order to keep the same as the defintion
in xen repo.

Note that page_to_mfn has been renamed to xen_page_to_gfn to avoid a
name to close to the KVM function gfn_to_page.

Take also the opportunity to simplify simple construction such
as pfn_to_mfn(page_to_pfn(page)) into xen_page_to_gfn. More complex clean up
will come in follow-up patches.

[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=e758ed14f390342513405dd766e874934573e6cb



Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

If an interface isn't running napi_synchronize() will hang forever.

[  392.248403] rmmod           R  running task        0   359    343 0x00000000
[  392.257671]  ffff88003760fc88 ffff880037193b40 ffff880037193160 ffff88003760fc88
[  392.267644]  ffff880037610000 ffff88003760fcd8 0000000100014c22 ffffffff81f75c40
[  392.277524]  0000000000bc7010 ffff88003760fca8 ffffffff81796927 ffffffff81f75c40
[  392.287323] Call Trace:
[  392.291599]  [<ffffffff81796927>] schedule+0x37/0x90
[  392.298553]  [<ffffffff8179985b>] schedule_timeout+0x14b/0x280
[  392.306421]  [<ffffffff810f91b9>] ? irq_free_descs+0x69/0x80
[  392.314006]  [<ffffffff811084d0>] ? internal_add_timer+0xb0/0xb0
[  392.322125]  [<ffffffff81109d07>] msleep+0x37/0x50
[  392.329037]  [<ffffffffa00ec79a>] xennet_disconnect_backend.isra.24+0xda/0x390 [xen_netfront]
[  392.339658]  [<ffffffffa00ecadc>] xennet_remove+0x2c/0x80 [xen_netfront]
[  392.348516]  [<ffffffff81481c69>] xenbus_dev_remove+0x59/0xc0
[  392.356257]  [<ffffffff814e7217>] __device_release_driver+0x87/0x120
[  392.364645]  [<ffffffff814e7cf8>] driver_detach+0xb8/0xc0
[  392.371989]  [<ffffffff814e6e69>] bus_remove_driver+0x59/0xe0
[  392.379883]  [<ffffffff814e84f0>] driver_unregister+0x30/0x70
[  392.387495]  [<ffffffff814814b2>] xenbus_unregister_driver+0x12/0x20
[  392.395908]  [<ffffffffa00ed89b>] netif_exit+0x10/0x775 [xen_netfront]
[  392.404877]  [<ffffffff81124e08>] SyS_delete_module+0x1d8/0x230
[  392.412804]  [<ffffffff8179a8ee>] system_call_fastpath+0x12/0x71

Signed-off-by: Chas Williams <3chas3@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

If you simply load and unload the module without starting the interfaces,
the queues are never created and you get a bad pointer dereference.

Signed-off-by: Chas Williams <3chas3@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The function netif_set_real_num_tx_queues() will return -EINVAL if
the second parameter < 1, so call this function with the second
parameter set to 0 is meaningless.

Signed-off-by: Liang Li <liang.z.li@intel.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

rx->status is an int16_t, print it using %d rather than %u in order to
have a meaningful value when the field is negative.

Also use %u rather than %x for rx->offset.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

Using xen/page.h will be necessary later for using common xen page
helpers.

As xen/page.h already include asm/xen/page.h, always use the later.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: netdev@vger.kernel.org
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

Use the timer API function setup_timer instead of structure field
assignments to initialize a timer.

A simplified version of the Coccinelle semantic patch that performs
this transformation is as follows:

@change@
expression e, func, da;
@@

-init_timer (&e);
+setup_timer (&e, func, da);
-e.data = da;
-e.function = func;

Signed-off-by: Vaishali Thakkar <vthakkar1994@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xennet_remove() freed the queues before freeing the netdevice which
results in a use-after-free when free_netdev() tries to delete the
napi instances that have already been freed.

Fix this by fully destroy the queues (which includes deleting the napi
instances) before freeing the netdevice.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In commit 04ffcb25 ("net: Add ndo_gso_check") Tom originally
added the 'dev' argument to be able to call ndo_gso_check().

Then later, when generalizing this in commit 5f35227e
("net: Generalize ndo_gso_check to ndo_features_check")
Jesse removed the call to ndo_gso_check() in netif_needs_gso()
by calling the new ndo_features_check() in a different place.
This made the 'dev' argument unused.

Remove the unused argument and go back to the code as before.

Cc: Tom Herbert <therbert@google.com>
Cc: Jesse Gross <jesse@nicira.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Originally Xen PV drivers only use single-page ring to pass along
information. This might limit the throughput between frontend and
backend.

The patch extends Xenbus driver to support multi-page ring, which in
general should improve throughput if ring is the bottleneck. Changes to
various frontend / backend to adapt to the new interface are also
included.

Affected Xen drivers:
* blkfront/back
* netfront/back
* pcifront/back
* scsifront/back
* vtpmfront

The interface is documented, as before, in xenbus_client.c.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>