linux-toradex.git/drivers/hv/channel.c, branch v4.9.60

Drivers: hv: vmbus: Don't leak memory when a channel is rescinded

2017-03-30T07:41:27+00:00

commit 5e030d5ce9d99a899b648413139ff65bab12b038 upstream.

When we close a channel that has been rescinded, we will leak memory since
vmbus_teardown_gpadl() returns an error. Fix this so that we can properly
cleanup the memory allocated to the ring buffers.

Fixes: ccb61f8a99e6 ("Drivers: hv: vmbus: Fix a rescind handling bug")

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

Drivers: hv: vmbus: Fix a rescind handling bug

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

commit ccb61f8a99e6c29df4fb96a65dad4fad740d5be9 upstream.

The host can rescind a channel that has been offered to the
guest and once the channel is rescinded, the host does not
respond to any requests on that channel. Deal with the case where
the guest may be blocked waiting for a response from the host.

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

Drivers: hv: vmbus: Raise retry/wait limits in vmbus_post_msg()

2017-03-12T05:41:47+00:00

commit c0bb03924f1a80e7f65900e36c8e6b3dc167c5f8 upstream.

DoS protection conditions were altered in WS2016 and now it's easy to get
-EAGAIN returned from vmbus_post_msg() (e.g. when we try changing MTU on a
netvsc device in a loop). All vmbus_post_msg() callers don't retry the
operation and we usually end up with a non-functional device or crash.

While host's DoS protection conditions are unknown to me my tests show that
it can take up to 10 seconds before the message is sent so doing udelay()
is not an option, we really need to sleep. Almost all vmbus_post_msg()
callers are ready to sleep but there is one special case:
vmbus_initiate_unload() which can be called from interrupt/NMI context and
we can't sleep there. I'm also not sure about the lonely
vmbus_send_tl_connect_request() which has no in-tree users but its external
users are most likely waiting for the host to reply so sleeping there is
also appropriate.

Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: K. Y. Srinivasan 
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: 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: cleanup vmbus_open() for wrap around mappings

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

In preparation for doing wrap around mappings for ring buffers cleanup
vmbus_open() function:
- check that ring sizes are PAGE_SIZE aligned (they are for all in-kernel
  drivers now);
- kfree(open_info) on error only after we kzalloc() it (not an issue as it
  is valid to call kfree(NULL);
- rename poorly named labels;
- use alloc_pages() instead of __get_free_pages() as we need struct page
  pointer for future.

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

Drivers: hv: vmbus: Implement a mechanism to tag the channel for low latency

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

On Hyper-V, performance critical channels use the monitor
mechanism to signal the host when the guest posts mesages
for the host. This mechanism minimizes the hypervisor intercepts
and also makes the host more efficient in that each time the
host is woken up, it processes a batch of messages as opposed to
just one. The goal here is improve the throughput and this is at
the expense of increased latency.
Implement a mechanism to let the client driver decide if latency
is important.

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