hv_utils: Add comment about max VMbus packet size in VSS driver

The VSS driver allocates a VMbus receive buffer significantly
larger than sizeof(hv_vss_msg), with no explanation. To help
prevent future mistakes, add a #define and comment about why
this is done.

No functional change.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1644423070-75125-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

hv_utils: Set the maximum packet size for VSS driver to the length of the receive buffer

Commit adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out
of the ring buffer") introduced a notion of maximum packet size and for
KVM and FCOPY drivers set it to the length of the receive buffer. VSS
driver wasn't updated, this means that the maximum packet size is now
VMBUS_DEFAULT_MAX_PKT_SIZE (4k). Apparently, this is not enough. I'm
observing a packet of 6304 bytes which is being truncated to 4096. When
VSS driver tries to read next packet from ring buffer it starts from the
wrong offset and receives garbage.

Set the maximum packet size to 'HV_HYP_PAGE_SIZE * 2' in VSS driver. This
matches the length of the receive buffer and is in line with other utils
drivers.

Fixes: adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210825133857.847866-1-vkuznets@redhat.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

hv_utils: Add validation for untrusted Hyper-V values

For additional robustness in the face of Hyper-V errors or malicious
behavior, validate all values that originate from packets that Hyper-V
has sent to the guest in the host-to-guest ring buffer. Ensure that
invalid values cannot cause indexing off the end of the icversion_data
array in vmbus_prep_negotiate_resp().

Signed-off-by: Andres Beltran <lkmlabelt@gmail.com>
Co-developed-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20201109100704.9152-1-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

hv_utils: Always execute the fcopy and vss callbacks in a tasklet

The fcopy and vss callback functions could be running in a tasklet
at the same time they are called in hv_poll_channel(). Current code
serializes the invocations of these functions, and their accesses to
the channel ring buffer, by sending an IPI to the CPU that is allowed
to access the ring buffer, cf. hv_poll_channel(). This IPI mechanism
becomes infeasible if we allow changing the CPU that a channel will
interrupt. Instead modify the callback wrappers to always execute
the fcopy and vss callbacks in a tasklet, thus mirroring the solution
for the kvp callback functions adopted since commit a3ade8cc474d8
("HV: properly delay KVP packets when negotiation is in progress").
This will ensure that the callback function can't run on two CPUs at
the same time.

Suggested-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200406001514.19876-6-parri.andrea@gmail.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

hv_utils: Add the support of hibernation

Add util_pre_suspend() and util_pre_resume() for some hv_utils devices
(e.g. kvp/vss/fcopy), because they need special handling before
util_suspend() calls vmbus_close().

For kvp, all the possible pending work items should be cancelled.

For vss and fcopy, some extra clean-up needs to be done, i.e. fake a
THAW message for hv_vss_daemon and fake a CANCEL_FCOPY message for
hv_fcopy_daemon, otherwise when the VM resums back, the daemons
can end up in an inconsistent state (i.e. the file systems are
frozen but will never be thawed; the file transmitted via fcopy
may not be complete). Note: there is an extra patch for the daemons:
"Tools: hv: Reopen the devices if read() or write() returns errors",
because the hv_utils driver can not guarantee the whole transaction
finishes completely once util_suspend() starts to run (at this time,
all the userspace processes are frozen).

util_probe() disables channel->callback_event to avoid the race with
the channel callback.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Drivers: hv: Specify receive buffer size using Hyper-V page size

The recv_buffer is used to retrieve data from the VMbus ring buffer.
VMbus ring buffers are sized based on the guest page size which
Hyper-V assumes to be 4KB. But it may be different on some
architectures. So use the Hyper-V page size to allocate the
recv_buffer and set the maximum size to receive.

Signed-off-by: Himadri Pandya <himadri18.07@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 280

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose good title or non infringement see
the gnu general public license for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 9 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141900.459653302@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

vmbus: remove useless return's

No need for empty return at end of void function

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: util: move waiting for release to hv_utils_transport itself

Waiting for release_event in all three drivers introduced issues on release
as on_reset() hook is not always called. E.g. if the device was never
opened we will never get the completion.

Move the waiting code to hvutil_transport_destroy() and make sure it is
only called when the device is open. hvt->lock serialization should
guarantee the absence of races.

Fixes: 5a66fecbf6aa ("Drivers: hv: util: kvp: Fix a rescind processing issue")
Fixes: 20951c7535b5 ("Drivers: hv: util: Fcopy: Fix a rescind processing issue")
Fixes: d77044d142e9 ("Drivers: hv: util: Backup: Fix a rescind processing issue")

Reported-by: Dexuan Cui <decui@microsoft.com>
Tested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: Log the negotiated IC versions.

Log the negotiated IC versions.

Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vmbus: Use all supported IC versions to negotiate

Previously, we were assuming that each IC protocol version was tied to a
specific host version. For example, some Windows 10 preview hosts only
support v3 TimeSync even though driver assumes v4 is supported by all
Windows 10 hosts.

The guest will stop trying to negotiate even though older supported
versions may still be offered by the host.

Make IC version negotiation more robust by going through all versions
that are supported by the guest.

Fixes: 3da0401b4d0e ("Drivers: hv: utils: Fix the mapping between host
version and protocol to use")

Reported-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: util: Backup: Fix a rescind processing issue

VSS may use a char device to support the communication between
the user level daemon and the driver. When the VSS channel is rescinded
we need to make sure that the char device is fully cleaned up before
we can process a new VSS offer from the host. Implement this logic.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: Operation timeouts should match host expectation

Increase the timeout of backup operations. When system is under I/O load,
it needs more time to freeze. These timeout values should also match the
host timeout values more closely.

Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: Improve log messages.

Adding log messages to help troubleshoot error cases and transaction
handling.

Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: utils: Check VSS daemon is listening before a hot backup

Hyper-V host will send a VSS_OP_HOT_BACKUP request to check if guest is
ready for a live backup/snapshot. The driver should respond to the check
only if the daemon is running and listening to requests. This allows the
host to fallback to standard snapshots in case the VSS daemon is not
running.

Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: utils: Continue to poll VSS channel after handling requests.

Multiple VSS_OP_HOT_BACKUP requests may arrive in quick succession, even
though the host only signals once. The driver wass handling the first
request while ignoring the others in the ring buffer. We should poll the
VSS channel after handling a request to continue processing other requests.

Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: utils: fix a race on userspace daemons registration

Background: userspace daemons registration protocol for Hyper-V utilities
drivers has two steps:
1) daemon writes its own version to kernel
2) kernel reads it and replies with module version
at this point we consider the handshake procedure being completed and we
do hv_poll_channel() transitioning the utility device to HVUTIL_READY
state. At this point we're ready to handle messages from kernel.

When hvutil_transport is in HVUTIL_TRANSPORT_CHARDEV mode we have a
single buffer for outgoing message. hvutil_transport_send() puts to this
buffer and till the buffer is cleared with hvt_op_read() returns -EFAULT
to all consequent calls. Host<->guest protocol guarantees there is no more
than one request at a time and we will not get new requests till we reply
to the previous one so this single message buffer is enough.

Now to the race. When we finish negotiation procedure and send kernel
module version to userspace with hvutil_transport_send() it goes into the
above mentioned buffer and if the daemon is slow enough to read it from
there we can get a collision when a request from the host comes, we won't
be able to put anything to the buffer so the request will be lost. To
solve the issue we need to know when the negotiation is really done (when
the version message is read by the daemon) and transition to HVUTIL_READY
state after this happens. Implement a callback on read to support this.
Old style netlink communication is not affected by the change, we don't
really know when these messages are delivered but we don't have a single
message buffer there.

Reported-by: Barry Davis <barry_davis@stormagic.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: util: Pass the channel information during the init call

Pass the channel information to the util drivers that need to defer
reading the channel while they are processing a request. This would address
the following issue reported by Vitaly:

Commit 3cace4a61610 ("Drivers: hv: utils: run polling callback always in
interrupt context") removed direct *_transaction.state = HVUTIL_READY
assignments from *_handle_handshake() functions introducing the following
race: if a userspace daemon connects before we get first non-negotiation
request from the server hv_poll_channel() won't set transaction state to
HVUTIL_READY as (!channel) condition will fail, we set it to non-NULL on
the first real request from the server.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: utils: Invoke the poll function after handshake

When the handshake with daemon is complete, we should poll the channel since
during the handshake, we will not be processing any messages. This is a
potential bug if the host is waiting for a response from the guest.
I would like to thank Dexuan for pointing this out.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: run only on supported host versions

The Backup integration service on WS2012 has appearently trouble to
negotiate with a guest which does not support the provided util version.
Currently the VSS driver supports only version 5/0. A WS2012 offers only
version 1/x and 3/x, and vmbus_prep_negotiate_resp correctly returns an
empty icframe_vercnt/icmsg_vercnt. But the host ignores that and
continues to send ICMSGTYPE_NEGOTIATE messages. The result are weird
errors during boot and general misbehaviour.

Check the Windows version to work around the host bug, skip hv_vss_init
on WS2012 and older.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: utils: run polling callback always in interrupt context

All channel interrupts are bound to specific VCPUs in the guest
at the point channel is created. While currently, we invoke the
polling function on the correct CPU (the CPU to which the channel
is bound to) in some cases we may run the polling function in
a non-interrupt context. This potentially can cause an issue as the
polling function can be interrupted by the channel callback function.
Fix the issue by running the polling function on the appropriate CPU
at interrupt level. Additional details of the issue being addressed by
this patch are given below:

Currently hv_fcopy_onchannelcallback is called from interrupts and also
via the ->write function of hv_utils. Since the used global variables to
maintain state are not thread safe the state can get out of sync.
This affects the variable state as well as the channel inbound buffer.

As suggested by KY adjust hv_poll_channel to always run the given
callback on the cpu which the channel is bound to. This avoids the need
for locking because all the util services are single threaded and only
one transaction is active at any given point in time.

Additionally, remove the context variable, they will always be the same as
recv_channel.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: utils: unify driver registration reporting

Unify driver registration reporting and move it to debug level as normally daemons write to syslog themselves
and these kernel messages are useless.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: full handshake support

Introduce VSS_OP_REGISTER1 to support kernel replying to the negotiation
message with its own version.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: convert to hv_utils_transport

Convert to hv_utils_transport to support both netlink and /dev/vmbus/hv_vss communication methods.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: switch to using the hvutil_device_state state machine

Switch to using the hvutil_device_state state machine from using kvp_transaction.active.

State transitions are:
-> HVUTIL_DEVICE_INIT when driver loads or on device release
-> HVUTIL_READY if the handshake was successful
-> HVUTIL_HOSTMSG_RECEIVED when there is a non-negotiation message from the host
-> HVUTIL_USERSPACE_REQ after we sent the message to the userspace daemon
-> HVUTIL_USERSPACE_RECV after/if the userspace daemon has replied
-> HVUTIL_READY after we respond to the host
-> HVUTIL_DEVICE_DYING on driver unload

In hv_vss_onchannelcallback() process ICMSGTYPE_NEGOTIATE messages even when
the userspace daemon is disconnected, otherwise we can make the host think
we don't support VSS and disable the service completely.

Unfortunately there is no good way we can figure out that the userspace daemon
has died (unless we start treating all timeouts as such), add a protection
against processing new VSS_OP_REGISTER messages while being in the middle of a
transaction (HVUTIL_USERSPACE_REQ or HVUTIL_USERSPACE_RECV state).

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: process deferred messages when we complete the transaction

In theory, the host is not supposed to issue any requests before be reply to
the previous one. In KVP we, however, support the following scenarios:
1) A message was received before userspace daemon registered;
2) A message was received while the previous one is still being processed.
In VSS we support only the former. Add support for the later, use
hv_poll_channel() to do the job.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: util: move kvp/vss function declarations to hyperv_vmbus.h

These declarations are internal to hv_util module and hv_fcopy_* declarations
already reside there.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: kvp,vss: Fast propagation of userspace communication failure

If we fail to send a message to userspace daemon with cn_netlink_send()
there is no need to wait for userspace to reply as it is not going to
happen. This happens when kvp or vss daemon is stopped after a successful
handshake. Report HV_E_FAIL immediately and cancel the timeout job so
host won't receive two failures.
Use pr_warn() for VSS and pr_debug() for KVP deliberately as VSS request
are rare and result in a failed backup. KVP requests are much more frequent
after a successful handshake so avoid flooding logs. It would be nice to
have an ability to de-negotiate with the host in case userspace daemon gets
disconnected so we won't receive new requests. But I'm not sure it is
possible.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: vss: Introduce timeout for communication with userspace

In contrast with KVP there is no timeout when communicating with
userspace VSS daemon. In case it gets stuck performing freeze/thaw
operation no message will be sent to the host so it will take very
long (around 10 minutes) before backup fails. Introduce 10 second
timeout using schedule_delayed_work().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

connector: add portid to unicast in addition to broadcasting

This allows replying only to the requestor portid while still
supporting broadcasting. Pass 0 to portid for the previous behavior.

Signed-off-by: David Fries <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: util: Correctly support ws2008R2 and earlier

The current code does not correctly negotiate the version numbers for the util
driver when hosted on earlier hosts. The version numbers presented by this
driver were not compatible with the version numbers supported by Windows Server
2008. Fix this problem.

I would like to thank Olaf Hering (ohering@suse.com) for identifying the problem.

Reported-by: Olaf Hering <ohering@suse.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: util: Fix a bug in version negotiation code for util services

The current code picked the highest version advertised by the host. WS2012 R2
has implemented a protocol version for KVP that is not compatible with prior
protocol versions of KVP. Fix the bug in the current code by explicitly specifying
the protocol version that the guest can support.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drivers: hv: Add a new driver to support host initiated backup

This driver supports host initiated backup of the guest. On Windows guests,
the host can generate application consistent backups using the Windows VSS
framework. On Linux, we ensure that the backup will be file system consistent.
This driver allows the host to initiate a "Freeze" operation on all the mounted
file systems in the guest. Once the mounted file systems in the guest are frozen,
the host snapshots the guest's file systems. Once this is done, the guest's file
systems are "thawed".

This driver has a user-level component (daemon) that invokes the appropriate
operation on all the mounted file systems in response to the requests from
the host. The duration for which the guest is frozen is very short - a few seconds.
During this interval, the diff disk is comitted.

In this version of the patch I have addressed the feedback from Olaf Herring.
Also, some of the connector related issues have been fixed.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>