76e527509d
Skip the optimized cluster[] setup for x2APIC logical mode, as KVM reuses the optimized map's phys_map[] and doesn't actually need to insert the target apic into the cluster[]. The LDR is derived from the x2APIC ID, and both are read-only in KVM, thus the vCPU's cluster[ldr] is guaranteed to be the same entry as the vCPU's phys_map[x2apic_id] entry. Skipping the unnecessary setup will allow a future fix for aliased xAPIC logical IDs to simply require that cluster[ldr] is non-NULL, i.e. won't have to special case x2APIC. Alternatively, the future check could allow "cluster[ldr] == apic", but that ends up being terribly confusing because cluster[ldr] is only set at the very end, i.e. it's only possible due to x2APIC's shenanigans. Another alternative would be to send x2APIC down a separate path _after_ the calculation and then assert that all of the above, but the resulting code is rather messy, and it's arguably unnecessary since asserting that the actual LDR matches the expected LDR means that simply testing that interrupts are delivered correctly provides the same guarantees. Reported-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20230106011306.85230-20-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.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 Restructured Text 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.