Pass in the Linux IRQ associated with an IRQ bypass producer instead of
relying on the caller to set the field prior to registration, as there's
no benefit to relying on callers to do the right thing.
Take care to set producer->irq before __connect(), as KVM expects the IRQ
to be valid as soon as a connection is possible.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Track IRQ bypass producers and consumers using an xarray to avoid the O(2n)
insertion time associated with walking a list to check for duplicate
entries, and to search for an partner.
At low (tens or few hundreds) total producer/consumer counts, using a list
is faster due to the need to allocate backing storage for xarray. But as
count creeps into the thousands, xarray wins easily, and can provide
several orders of magnitude better latency at high counts. E.g. hundreds
of nanoseconds vs. hundreds of milliseconds.
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: David Matlack <dmatlack@google.com>
Cc: Like Xu <like.xu.linux@gmail.com>
Cc: Binbin Wu <binbin.wu@linux.intel.com>
Reported-by: Yong He <alexyonghe@tencent.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217379
Link: https://lore.kernel.org/all/20230801115646.33990-1-likexu@tencent.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Use guard(mutex) to clean up irqbypass's error handling.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Use the paired consumer/producer information to disconnect IRQ bypass
producers/consumers in O(1) time (ignoring the cost of __disconnect()).
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Explicitly track IRQ bypass producer:consumer bindings. This will allow
making removal an O(1) operation; searching through the list to find
information that is trivially tracked (and useful for debug) is wasteful.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Move ownership of IRQ bypass token tracking into irqbypass.ko, and
explicitly require callers to pass an eventfd_ctx structure instead of a
completely opaque token. Relying on producers and consumers to set the
token appropriately is error prone, and hiding the fact that the token must
be an eventfd_ctx pointer (for all intents and purposes) unnecessarily
obfuscates the code and makes it more brittle.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Drop superfluous might_sleep() annotations from irqbypass, mutex_lock()
provides all of the necessary tracking.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Drop irqbypass.ko's superfluous and misleading get/put calls on
THIS_MODULE. A module taking a reference to itself is useless; no amount
of checks will prevent doom and destruction if the caller hasn't already
guaranteed the liveliness of the module (this goes for any module). E.g.
if try_module_get() fails because irqbypass.ko is being unloaded, then the
kernel has already hit a use-after-free by virtue of executing code whose
lifecycle is tied to irqbypass.ko.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This reverts commit a979a6aa00.
The reverted commit may cause VM freeze on arm64 with GICv4,
where stopping a consumer is implemented by suspending the VM.
Should the connect fail, the VM will not be resumed, which
is a bit of a problem.
It also erroneously calls the producer destructor unconditionally,
which is unexpected.
Reported-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Suggested-by: Marc Zyngier <maz@kernel.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
[maz: tags and cc-stable, commit message update]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Fixes: a979a6aa00 ("irqbypass: do not start cons/prod when failed connect")
Link: https://lore.kernel.org/r/3a2c66d6-6ca0-8478-d24b-61e8e3241b20@hisilicon.com
Link: https://lore.kernel.org/r/20210508071152.722425-1-lingshan.zhu@intel.com
Cc: stable@vger.kernel.org
If failed to connect, there is no need to start consumer nor
producer.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20200731065533.4144-7-lingshan.zhu@intel.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Use out_err jump label to handle resource release. It's a
good practice to release resource in one place and help
eliminate some duplicated code.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use out_err jump label to handle resource release. It's a
good practice to release resource in one place and help
eliminate some duplicated code.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Based on 2 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 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 #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported syzkaller:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
PGD 0
Oops: 0002 [#1] SMP
CPU: 1 PID: 125 Comm: kworker/1:1 Not tainted 4.9.0+ #1
Workqueue: kvm-irqfd-cleanup irqfd_shutdown [kvm]
task: ffff9bbe0dfbb900 task.stack: ffffb61802014000
RIP: 0010:irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
Call Trace:
irqfd_shutdown+0x66/0xa0 [kvm]
process_one_work+0x16b/0x480
worker_thread+0x4b/0x500
kthread+0x101/0x140
? process_one_work+0x480/0x480
? kthread_create_on_node+0x60/0x60
ret_from_fork+0x25/0x30
RIP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass] RSP: ffffb61802017e20
CR2: 0000000000000008
The syzkaller folks reported a NULL pointer dereference that due to
unregister an consumer which fails registration before. The syzkaller
creates two VMs w/ an equal eventfd occasionally. So the second VM
fails to register an irqbypass consumer. It will make irqfd as inactive
and queue an workqueue work to shutdown irqfd and unregister the irqbypass
consumer when eventfd is closed. However, the second consumer has been
initialized though it fails registration. So the token(same as the first
VM's) is taken to unregister the consumer through the workqueue, the
consumer of the first VM is found and unregistered, then NULL deref incurred
in the path of deleting consumer from the consumers list.
This patch fixes it by making irq_bypass_register/unregister_consumer()
looks for the consumer entry based on consumer pointer itself instead of
token matching.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Cc: stable@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A NULL token is meaningless and can only lead to unintended problems.
Error on registration with a NULL token, ignore de-registrations with
a NULL token.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When a physical I/O device is assigned to a virtual machine through
facilities like VFIO and KVM, the interrupt for the device generally
bounces through the host system before being injected into the VM.
However, hardware technologies exist that often allow the host to be
bypassed for some of these scenarios. Intel Posted Interrupts allow
the specified physical edge interrupts to be directly injected into a
guest when delivered to a physical processor while the vCPU is
running. ARM IRQ Forwarding allows forwarded physical interrupts to
be directly deactivated by the guest.
The IRQ bypass manager here is meant to provide the shim to connect
interrupt producers, generally the host physical device driver, with
interrupt consumers, generally the hypervisor, in order to configure
these bypass mechanism. To do this, we base the connection on a
shared, opaque token. For KVM-VFIO this is expected to be an
eventfd_ctx since this is the connection we already use to connect an
eventfd to an irqfd on the in-kernel path. When a producer and
consumer with matching tokens is found, callbacks via both registered
participants allow the bypass facilities to be automatically enabled.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
