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b3a37bff8d
Reject KVM_CREATE_IRQCHIP if the VM type has protected EOIs, i.e. if KVM can't intercept EOI and thus can't faithfully emulate level-triggered interrupts that are routed through the I/O APIC. For TDX VMs, the TDX-Module owns the VMX EOI-bitmap and configures all IRQ vectors to have the CPU accelerate EOIs, i.e. doesn't allow KVM to intercept any EOIs. KVM already requires a split irqchip[1], but does so during vCPU creation, which is both too late to allow userspace to fallback to a split irqchip and a less-than-stellar experience for userspace since an -EINVAL on KVM_VCPU_CREATE is far harder to debug/triage than failure exactly on KVM_CREATE_IRQCHIP. And of course, allowing an action that ultimately fails is arguably a bug regardless of the impact on userspace. Link: https://lore.kernel.org/lkml/20250222014757.897978-11-binbin.wu@linux.intel.com [1] Link: https://lore.kernel.org/lkml/aK3vZ5HuKKeFuuM4@google.com Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Sagi Shahar <sagis@google.com> Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com> Acked-by: Kai Huang <kai.huang@intel.com> Link: https://lore.kernel.org/r/20250827011726.2451115-1-sagis@google.com [sean: massage shortlog+changelog, relocate setting has_protected_eoi] Signed-off-by: Sean Christopherson <seanjc@google.com>
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.