Paolo Bonzini f02b1bcc73 Merge tag 'kvm-x86-irqs-6.17' of https://github.com/kvm-x86/linux into HEAD
KVM IRQ changes for 6.17

 - Rework irqbypass to track/match producers and consumers via an xarray
   instead of a linked list.  Using a linked list leads to O(n^2) insertion
   times, which is hugely problematic for use cases that create large numbers
   of VMs.  Such use cases typically don't actually use irqbypass, but
   eliminating the pointless registration is a future problem to solve as it
   likely requires new uAPI.

 - Track irqbypass's "token" as "struct eventfd_ctx *" instead of a "void *",
   to avoid making a simple concept unnecessarily difficult to understand.

 - Add CONFIG_KVM_IOAPIC for x86 to allow disabling support for I/O APIC, PIC,
   and PIT emulation at compile time.

 - Drop x86's irq_comm.c, and move a pile of IRQ related code into irq.c.

 - Fix a variety of flaws and bugs in the AVIC device posted IRQ code.

 - Inhibited AVIC if a vCPU's ID is too big (relative to what hardware
   supports) instead of rejecting vCPU creation.

 - Extend enable_ipiv module param support to SVM, by simply leaving IsRunning
   clear in the vCPU's physical ID table entry.

 - Disable IPI virtualization, via enable_ipiv, if the CPU is affected by
   erratum #1235, to allow (safely) enabling AVIC on such CPUs.

 - Dedup x86's device posted IRQ code, as the vast majority of functionality
   can be shared verbatime between SVM and VMX.

 - Harden the device posted IRQ code against bugs and runtime errors.

 - Use vcpu_idx, not vcpu_id, for GA log tag/metadata, to make lookups O(1)
   instead of O(n).

 - Generate GA Log interrupts if and only if the target vCPU is blocking, i.e.
   only if KVM needs a notification in order to wake the vCPU.

 - Decouple device posted IRQs from VFIO device assignment, as binding a VM to
   a VFIO group is not a requirement for enabling device posted IRQs.

 - Clean up and document/comment the irqfd assignment code.

 - Disallow binding multiple irqfds to an eventfd with a priority waiter, i.e.
   ensure an eventfd is bound to at most one irqfd through the entire host,
   and add a selftest to verify eventfd:irqfd bindings are globally unique.
2025-07-29 08:35:46 -04:00
2022-09-28 09:02:20 +02:00
2025-07-19 19:26:16 -07:00
2025-02-19 14:53:27 -07:00
2025-07-27 14:26:38 -07:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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