kernel.git/drivers/hv/connection.c, branch linux-5.4.y

Drivers: hv: vmbus: Always handle the VMBus messages on CPU0

2020-06-22T07:31:00Z

[ Upstream commit 8a857c55420f29da4fc131adc22b12d474c48f4c ] A Linux guest have to pick a "connect CPU" to communicate with the Hyper-V host. This CPU can not be taken offline because Hyper-V does not provide a way to change that CPU assignment. Current code sets the connect CPU to whatever CPU ends up running the function vmbus_negotiate_version(), and this will generate problems if that CPU is taken offine. Establish CPU0 as the connect CPU, and add logics to prevents the connect CPU from being taken offline. We could pick some other CPU, and we could pick that "other CPU" dynamically if there was a reason to do so at some point in the future. But for now, #defining the connect CPU to 0 is the most straightforward and least complex solution. While on this, add inline comments explaining "why" offer and rescind messages should not be handled by a same serialized work queue. Suggested-by: Dexuan Cui Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/20200406001514.19876-2-parri.andrea@gmail.com Reviewed-by: Michael Kelley Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Resume after fixing up old primary channels

2019-09-06T18:52:44Z

When the host re-offers the primary channels upon resume, the host only guarantees the Instance GUID doesn't change, so vmbus_bus_suspend() should invalidate channel->offermsg.child_relid and figure out the number of primary channels that need to be fixed up upon resume. Upon resume, vmbus_onoffer() finds the old channel structs, and maps the new offers to the old channels, and fixes up the old structs, and finally the resume callbacks of the VSC drivers will re-open the channels. Signed-off-by: Dexuan Cui Reviewed-by: Michael Kelley Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Suspend after cleaning up hv_sock and sub channels

2019-09-06T18:52:44Z

Before suspend, Linux must make sure all the hv_sock channels have been properly cleaned up, because a hv_sock connection can not persist across hibernation, and the user-space app must be properly notified of the state change of the connection. Before suspend, Linux also must make sure all the sub-channels have been destroyed, i.e. the related channel structs of the sub-channels must be properly removed, otherwise they would cause a conflict when the sub-channels are recreated upon resume. Add a counter to track such channels, and vmbus_bus_suspend() should wait for the counter to drop to zero. Signed-off-by: Dexuan Cui Reviewed-by: Michael Kelley Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation

2019-09-06T18:52:44Z

Before Linux enters hibernation, it sends the CHANNELMSG_UNLOAD message to the host so all the offers are gone. After hibernation, Linux needs to re-negotiate with the host using the same vmbus protocol version (which was in use before hibernation), and ask the host to re-offer the vmbus devices. Signed-off-by: Dexuan Cui Reviewed-by: Michael Kelley Signed-off-by: Sasha Levin

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 320

2019-06-05T15:37:05Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms and conditions of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 33 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Kate Stewart Reviewed-by: Alexios Zavras Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190530000435.254582722@linutronix.de Signed-off-by: Greg Kroah-Hartman

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

2018-12-03T07:01:01Z

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()

2018-09-30T15:49:55Z

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 *

2018-05-15T07:40:37Z

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

2018-05-14T14:06:48Z

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

2018-03-28T20:47:06Z

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