• Thomas Gleixner's avatar
    x86/cpu: Deal with broken firmware (VMWare/XEN) · d49597fd
    Thomas Gleixner authored
    Both ACPI and MP specifications require that the APIC id in the respective
    tables must be the same as the APIC id in CPUID.
    
    The kernel retrieves the physical package id from the APIC id during the
    ACPI/MP table scan and builds the physical to logical package map. The
    physical package id which is used after a CPU comes up is retrieved from
    CPUID. So we rely on ACPI/MP tables and CPUID agreeing in that respect.
    
    There exist VMware and XEN implementations which violate the spec. As a
    result the physical to logical package map, which relies on the ACPI/MP
    tables does not work on those systems, because the CPUID initialized
    physical package id does not match the firmware id. This causes system
    crashes and malfunction due to invalid package mappings.
    
    The only way to cure this is to sanitize the physical package id after the
    CPUID enumeration and yell when the APIC ids are different. Fix up the
    initial APIC id, which is fine as it is only used printout purposes.
    
    If the physical package IDs differ yell and use the package information
    from the ACPI/MP tables so the existing logical package map just works.
    
    Chas provided the resulting dmesg output for his affected 4 virtual
    sockets, 1 core per socket VM:
    
    [Firmware Bug]: CPU1: APIC id mismatch. Firmware: 1 CPUID: 2
    [Firmware Bug]: CPU1: Using firmware package id 1 instead of 2
    ....
    
    Reported-and-tested-by: "Charles (Chas) Williams" <ciwillia@brocade.com>,
    Reported-by: default avatarM. Vefa Bicakci <m.v.b@runbox.com>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Alok Kataria <akataria@vmware.com>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: #4.6+ <stable@vger,kernel.org>
    Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1611091613540.3501@nanosSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    d49597fd
common.c 39.6 KB