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commit b14c876b994f208b6b95c222056e1deb0a45de0e upstream. recalculate_apic_map does not santize ldr and it's possible that multiple bits are set. In that case, a previous valid entry can potentially be overwritten by an invalid one. This condition is hit when booting a 32 bit, >8 CPU, RHEL6 guest and then triggering a crash to boot a kdump kernel. This is the sequence of events: 1. Linux boots in bigsmp mode and enables PhysFlat, however, it still writes to the LDR which probably will never be used. 2. However, when booting into kdump, the stale LDR values remain as they are not cleared by the guest and there isn't a apic reset. 3. kdump boots with 1 cpu, and uses Logical Destination Mode but the logical map has been overwritten and points to an inactive vcpu. Signed-off-by: Radim Krcmar <rkrcmar@redhat.com> Signed-off-by: Bandan Das <bsd@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.