linux-stable.git/drivers/hv/ring_buffer.c, branch linux-4.9.y

Drivers: hv: vmbus: Prevent sending data on a rescinded channel

2017-03-12T05:41:49+00:00

commit e7e97dd8b77ee7366f2f8c70a033bf5fa05ec2e0 upstream.

After the channel is rescinded, the host does not read from the rescinded channel.
Fail writes to a channel that has already been rescinded. If we permit writes on a
rescinded channel, since the host will not respond we will have situations where
we will be unable to unload vmbus drivers that cannot have any outstanding requests
to the host at the point they are unoaded.

Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: finally fix hv_need_to_signal_on_read()

2017-02-14T23:25:39+00:00

commit 433e19cf33d34bb6751c874a9c00980552fe508c upstream.

Commit a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in
hv_need_to_signal_on_read()")
added the proper mb(), but removed the test "prev_write_sz < pending_sz"
when making the signal decision.

As a result, the guest can signal the host unnecessarily,
and then the host can throttle the guest because the host
thinks the guest is buggy or malicious; finally the user
running stress test can perceive intermittent freeze of
the guest.

This patch brings back the test, and properly handles the
in-place consumption APIs used by NetVSC (see get_next_pkt_raw(),
put_pkt_raw() and commit_rd_index()).

Fixes: a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in
hv_need_to_signal_on_read()")

Signed-off-by: Dexuan Cui 
Reported-by: Rolf Neugebauer 
Tested-by: Rolf Neugebauer 
Cc: "K. Y. Srinivasan" 
Cc: Haiyang Zhang 
Cc: Stephen Hemminger 
Signed-off-by: K. Y. Srinivasan 
Cc: Rolf Neugebauer 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: On the read path cleanup the logic to interrupt the host

2017-02-14T23:25:38+00:00

commit 3372592a140db69fd63837e81f048ab4abf8111e upstream.

Signal the host when we determine the host is to be signaled -
on th read path. The currrent code determines the need to signal in the
ringbuffer code and actually issues the signal elsewhere. This can result
in the host viewing this interrupt as spurious since the host may also
poll the channel. Make the necessary adjustments.

Signed-off-by: K. Y. Srinivasan 
Cc: Rolf Neugebauer 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: On write cleanup the logic to interrupt the host

2017-02-14T23:25:38+00:00

commit 1f6ee4e7d83586c8b10bd4f2f4346353d04ce884 upstream.

Signal the host when we determine the host is to be signaled.
The currrent code determines the need to signal in the ringbuffer
code and actually issues the signal elsewhere. This can result
in the host viewing this interrupt as spurious since the host may also
poll the channel. Make the necessary adjustments.

Signed-off-by: K. Y. Srinivasan 
Cc: Rolf Neugebauer 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Base host signaling strictly on the ring state

2017-02-14T23:25:38+00:00

commit 74198eb4a42c4a3c4fbef08fa01a291a282f7c2e upstream.

One of the factors that can result in the host concluding that a given
guest in mounting a DOS attack is if the guest generates interrupts
to the host when the host is not expecting it. If these "spurious"
interrupts reach a certain rate, the host can throttle the guest to
minimize the impact. The host computation of the "expected number
of interrupts" is strictly based on the ring transitions. Until
the host logic is fixed, base the guest logic to interrupt solely
on the ring state.

Signed-off-by: K. Y. Srinivasan 
Cc: Rolf Neugebauer 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: ring_buffer: use wrap around mappings in hv_copy{from, to}_ringbuffer()

2016-09-02T15:22:51+00:00

With wrap around mappings for ring buffers we can always use a single
memcpy() to do the job.

Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: K. Y. Srinivasan 
Tested-by: Dexuan Cui 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: ring_buffer: wrap around mappings for ring buffers

2016-09-02T15:22:51+00:00

Make it possible to always use a single memcpy() or to provide a direct
link to a packet on the ring buffer by creating virtual mapping for two
copies of the ring buffer with vmap(). Utilize currently empty
hv_ringbuffer_cleanup() to do the unmap.

While on it, replace sizeof(struct hv_ring_buffer) check
in hv_ringbuffer_init() with BUILD_BUG_ON() as it is a compile time check.

Signed-off-by: Vitaly Kuznetsov 
Tested-by: Dexuan Cui 
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Enable explicit signaling policy for NIC channels

2016-08-31T11:05:41+00:00

For synthetic NIC channels, enable explicit signaling policy as netvsc wants to
explicitly control when the host is to be signaled.

Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Implement APIs to support "in place" consumption of vmbus packets

2016-04-30T21:00:19+00:00

Implement APIs for in-place consumption of vmbus packets. Currently, each
packet is copied and processed one at a time and as part of processing
each packet we potentially may signal the host (if it is waiting for
room to produce a packet).

These APIs help batched in-place processing of vmbus packets.
We also optimize host signaling by having a separate API to signal
the end of in-place consumption. With netvsc using these APIs,
on an iperf run on average I see about 20X reduction in checks to
signal the host.

Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Move some ring buffer functions to hyperv.h

2016-04-30T21:00:19+00:00

In preparation for implementing APIs for in-place consumption of VMBUS
packets, movve some ring buffer functionality into hyperv.h

Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman