kernel/linux.git/virt/lib, branch v6.19.11

irqbypass: Require producers to pass in Linux IRQ number during registration

2025-06-20T20:52:41+00:00

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 Reviewed-by: Alex Williamson Acked-by: Michael S. Tsirkin Link: https://lore.kernel.org/r/20250516230734.2564775-9-seanjc@google.com Signed-off-by: Sean Christopherson

irqbypass: Use xarray to track producers and consumers

2025-06-20T20:52:40+00:00

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 Cc: David Matlack Cc: Like Xu Cc: Binbin Wu Reported-by: Yong He 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 Acked-by: Michael S. Tsirkin Reviewed-by: Alex Williamson Link: https://lore.kernel.org/r/20250516230734.2564775-8-seanjc@google.com Signed-off-by: Sean Christopherson

irqbypass: Use guard(mutex) in lieu of manual lock+unlock

2025-06-20T20:52:40+00:00

Use guard(mutex) to clean up irqbypass's error handling. Reviewed-by: Kevin Tian Acked-by: Michael S. Tsirkin Reviewed-by: Alex Williamson Link: https://lore.kernel.org/r/20250516230734.2564775-7-seanjc@google.com Signed-off-by: Sean Christopherson

irqbypass: Use paired consumer/producer to disconnect during unregister

2025-06-20T20:52:39+00:00

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 Acked-by: Michael S. Tsirkin Reviewed-by: Alex Williamson Link: https://lore.kernel.org/r/20250516230734.2564775-6-seanjc@google.com Signed-off-by: Sean Christopherson

irqbypass: Explicitly track producer and consumer bindings

2025-06-20T20:52:38+00:00

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 Acked-by: Michael S. Tsirkin Reviewed-by: Alex Williamson Link: https://lore.kernel.org/r/20250516230734.2564775-5-seanjc@google.com Signed-off-by: Sean Christopherson

irqbypass: Take ownership of producer/consumer token tracking

2025-06-20T20:52:38+00:00

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 Acked-by: Michael S. Tsirkin Reviewed-by: Alex Williamson Link: https://lore.kernel.org/r/20250516230734.2564775-4-seanjc@google.com Signed-off-by: Sean Christopherson

irqbypass: Drop superfluous might_sleep() annotations

2025-06-20T20:52:37+00:00

Drop superfluous might_sleep() annotations from irqbypass, mutex_lock() provides all of the necessary tracking. Reviewed-by: Kevin Tian Acked-by: Michael S. Tsirkin Reviewed-by: Alex Williamson Link: https://lore.kernel.org/r/20250516230734.2564775-3-seanjc@google.com Signed-off-by: Sean Christopherson

irqbypass: Drop pointless and misleading THIS_MODULE get/put

2025-06-20T20:52:36+00:00

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 Acked-by: Michael S. Tsirkin Reviewed-by: Alex Williamson Link: https://lore.kernel.org/r/20250516230734.2564775-2-seanjc@google.com Signed-off-by: Sean Christopherson

Revert "irqbypass: do not start cons/prod when failed connect"

2021-05-15T09:26:55+00:00

This reverts commit a979a6aa009f3c99689432e0cdb5402a4463fb88. 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 Suggested-by: Marc Zyngier Acked-by: Jason Wang Acked-by: Michael S. Tsirkin Reviewed-by: Eric Auger Tested-by: Shaokun Zhang Signed-off-by: Zhu Lingshan [maz: tags and cc-stable, commit message update] Signed-off-by: Marc Zyngier Fixes: a979a6aa009f ("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

irqbypass: do not start cons/prod when failed connect

2020-08-05T15:08:42+00:00

If failed to connect, there is no need to start consumer nor producer. Signed-off-by: Zhu Lingshan Suggested-by: Jason Wang Link: https://lore.kernel.org/r/20200731065533.4144-7-lingshan.zhu@intel.com Signed-off-by: Michael S. Tsirkin