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The hypercall VCPUOP_register_vcpu_info can fail. This failure is handled by making per_cpu(xen_vcpu, cpu) point to its shared_info slot and those without one (cpu >= MAX_VIRT_CPUS) be NULL. For PVH/PVHVM, this is not enough, because we also need to pull these VCPUs out of circulation. Fix for PVH/PVHVM: on registration failure in the cpuhp prepare callback (xen_cpu_up_prepare_hvm()), return an error to the cpuhp state-machine so it can fail the CPU init. Fix for PV: the registration happens before smp_init(), so, in the failure case we clamp setup_max_cpus and limit the number of VCPUs that smp_init() will bring-up to MAX_VIRT_CPUS. This is functionally correct but it makes the code a bit simpler if we get rid of this explicit clamping: for VCPUs that don't have valid xen_vcpu, fail the CPU init in the cpuhp prepare callback (xen_cpu_up_prepare_pv()). Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
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.