linux-toradex.git/drivers/hv/connection.c, branch v5.0

Drivers: hv: vmbus: Offload the handling of channels to two workqueues

2018-12-03T07:01:01+00:00

vmbus_process_offer() mustn't call channel->sc_creation_callback()
directly for sub-channels, because sc_creation_callback() ->
vmbus_open() may never get the host's response to the
OPEN_CHANNEL message (the host may rescind a channel at any time,
e.g. in the case of hot removing a NIC), and vmbus_onoffer_rescind()
may not wake up the vmbus_open() as it's blocked due to a non-zero
vmbus_connection.offer_in_progress, and finally we have a deadlock.

The above is also true for primary channels, if the related device
drivers use sync probing mode by default.

And, usually the handling of primary channels and sub-channels can
depend on each other, so we should offload them to different
workqueues to avoid possible deadlock, e.g. in sync-probing mode,
NIC1's netvsc_subchan_work() can race with NIC2's netvsc_probe() ->
rtnl_lock(), and causes deadlock: the former gets the rtnl_lock
and waits for all the sub-channels to appear, but the latter
can't get the rtnl_lock and this blocks the handling of sub-channels.

The patch can fix the multiple-NIC deadlock described above for
v3.x kernels (e.g. RHEL 7.x) which don't support async-probing
of devices, and v4.4, v4.9, v4.14 and v4.18 which support async-probing
but don't enable async-probing for Hyper-V drivers (yet).

The patch can also fix the hang issue in sub-channel's handling described
above for all versions of kernels, including v4.19 and v4.20-rc4.

So actually the patch should be applied to all the existing kernels,
not only the kernels that have 8195b1396ec8.

Fixes: 8195b1396ec8 ("hv_netvsc: fix deadlock on hotplug")
Cc: stable@vger.kernel.org
Cc: Stephen Hemminger 
Cc: K. Y. Srinivasan 
Cc: Haiyang Zhang 
Signed-off-by: Dexuan Cui 
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Use get/put_cpu() in vmbus_connect()

2018-09-30T15:49:55+00:00

With CONFIG_DEBUG_PREEMPT=y, I always see this warning:
BUG: using smp_processor_id() in preemptible [00000000]

Fix the false warning by using get/put_cpu().

Here vmbus_connect() sends a message to the host and waits for the
host's response. The host will deliver the response message and an
interrupt on CPU msg->target_vcpu, and later the interrupt handler
will wake up vmbus_connect(). vmbus_connect() doesn't really have
to run on the same cpu as CPU msg->target_vcpu, so it's safe to
call put_cpu() just here.

Signed-off-by: Dexuan Cui 
Cc: stable@vger.kernel.org
Cc: K. Y. Srinivasan 
Cc: Haiyang Zhang 
Cc: Stephen Hemminger 
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Removed an unnecessary cast from void *

2018-05-15T07:40:37+00:00

In C, we don't need such a cast.

Fixes: ae20b254306a ("Drivers: hv: vmbus: enable VMBus protocol version 5.0")
Reported-by: Stephen Hemminger 
Signed-off-by: Dexuan Cui 
Cc: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: enable VMBus protocol version 5.0

2018-05-14T14:06:48+00:00

With VMBus protocol 5.0, we're able to better support new features, e.g.
running two or more VMBus drivers simultaneously in a single VM -- note:
we can't simply load the current VMBus driver twice, instead, a secondary
VMBus driver must be implemented.

This patch adds the support for the new VMBus protocol, which is available
on new Windows hosts, by:

1) We still use SINT2 for compatibility;
2) We must use Connection ID 4 for the Initiate Contact Message, and for
subsequent messages, we must use the Message Connection ID field in
the host-returned VersionResponse Message.

Notes for developers of the secondary VMBus driver:
1) Must use VMBus protocol 5.0 as well;
2) Must use a different SINT number that is not in use.
3) Must use Connection ID 4 for the Initiate Contact Message, and for
subsequent messages, must use the Message Connection ID field in
the host-returned VersionResponse Message.
4) It's possible that the primary VMBus driver using protocol version 4.0
can work with a secondary VMBus driver using protocol version 5.0, but it's
recommended that both should use 5.0 for new Hyper-V features in the future.

Signed-off-by: Dexuan Cui 
Cc: Stephen Hemminger 
Cc: K. Y. Srinivasan 
Cc: Michael Kelley 
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

x86/hyper-v: move hyperv.h out of uapi

2018-03-28T20:47:06+00:00

hyperv.h is not part of uapi, there are no (known) users outside of kernel.
We are making changes to this file to match current Hyper-V Hypervisor
Top-Level Functional Specification (TLFS, see:
https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs)
and we don't want to maintain backwards compatibility.

Move the file renaming to hyperv-tlfs.h to avoid confusing it with
mshyperv.h. In future, all definitions from TLFS should go to it and
all kernel objects should go to mshyperv.h or include/linux/hyperv.h.

Signed-off-by: Vitaly Kuznetsov 
Acked-by: Thomas Gleixner 
Signed-off-by: Radim Krčmář

hyper-v: trace channel events

2017-11-04T11:04:26+00:00

Added an additional set of trace points for when channel gets notified
or signals host.

Suggested-by: Stephen Hemminger 
Signed-off-by: Vitaly Kuznetsov 
Signed-off-by: K. Y. Srinivasan 
Signed-off-by: Greg Kroah-Hartman

hyper-v: trace vmbus_negotiate_version()

2017-11-04T11:04:25+00:00

Add tracepoint to CHANNELMSG_INITIATE_CONTACT sender.

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

Drivers: hv: vmbus: Expose per-channel interrupts and events counters

2017-10-31T12:40:29+00:00

When investigating performance, it is useful to be able to look at
the number of host and guest events per-channel. This is equivalent
to per-device interrupt statistics.

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

hyper-v: Globalize vp_index

2017-08-10T14:50:23+00:00

To support implementing remote TLB flushing on Hyper-V with a hypercall
we need to make vp_index available outside of vmbus module. Rename and
globalize.

Signed-off-by: Vitaly Kuznetsov 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Stephen Hemminger 
Cc: Andy Lutomirski 
Cc: Haiyang Zhang 
Cc: Jork Loeser 
Cc: K. Y. Srinivasan 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Simon Xiao 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: devel@linuxdriverproject.org
Link: http://lkml.kernel.org/r/20170802160921.21791-7-vkuznets@redhat.com
Signed-off-by: Ingo Molnar

hyper-v: Use fast hypercall for HVCALL_SIGNAL_EVENT

2017-08-10T14:50:22+00:00

We need to pass only 8 bytes of input for HvSignalEvent which makes it a
perfect fit for fast hypercall. hv_input_signal_event_buffer is not needed
any more and hv_input_signal_event is converted to union for convenience.

Signed-off-by: Vitaly Kuznetsov 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Stephen Hemminger 
Cc: Andy Lutomirski 
Cc: Haiyang Zhang 
Cc: Jork Loeser 
Cc: K. Y. Srinivasan 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Simon Xiao 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: devel@linuxdriverproject.org
Link: http://lkml.kernel.org/r/20170802160921.21791-5-vkuznets@redhat.com
Signed-off-by: Ingo Molnar