• john cooper's avatar
    Add cpu model configuration support.. · b5ec5ce0
    john cooper authored
    This is a reimplementation of prior versions which adds
    the ability to define cpu models for contemporary processors.
    The added models are likewise selected via -cpu <name>,
    and are intended to displace the existing convention
    of "-cpu qemu64" augmented with a series of feature flags.
    
    A primary motivation was determination of a least common
    denominator within a given processor class to simplify guest
    migration.  It is still possible to modify an arbitrary model
    via additional feature flags however the goal here was to
    make doing so unnecessary in typical usage.  The other
    consideration was providing models names reflective of
    current processors.  Both AMD and Intel have reviewed the
    models in terms of balancing generality of migration vs.
    excessive feature downgrade relative to released silicon.
    
    This version of the patch replaces the prior hard wired
    definitions with a configuration file approach for new
    models.  Existing models are thus far left as-is but may
    easily be transitioned to (or may be overridden by) the
    configuration file representation.
    
    Proposed new model definitions are provided here for current
    AMD and Intel processors.  Each model consists of a name
    used to select it on the command line (-cpu <name>), and a
    model_id which corresponds to a least common denominator
    commercial instance of the processor class.
    
    A table of names/model_ids may be queried via "-cpu ?model":
    
            :
        x86       Opteron_G3  AMD Opteron 23xx (Gen 3 Class Opteron)
        x86       Opteron_G2  AMD Opteron 22xx (Gen 2 Class Opteron)
        x86       Opteron_G1  AMD Opteron 240 (Gen 1 Class Opteron)
        x86          Nehalem  Intel Core i7 9xx (Nehalem Class Core i7)
        x86           Penryn  Intel Core 2 Duo P9xxx (Penryn Class Core 2)
        x86           Conroe  Intel Celeron_4x0 (Conroe/Merom Class Core 2)
            :
    
    Also added is "-cpu ?dump" which exhaustively outputs all config
    data for all defined models, and "-cpu ?cpuid" which enumerates
    all qemu recognized CPUID feature flags.
    
    The pseudo cpuid flag 'check' when added to the feature flag list
    will warn when feature flags (either implicit in a cpu model or
    explicit on the command line) would have otherwise been quietly
    unavailable to a guest:
    
        # qemu-system-x86_64 ... -cpu Nehalem,check
        warning: host cpuid 0000_0001 lacks requested flag 'sse4.2|sse4_2' [0x00100000]
        warning: host cpuid 0000_0001 lacks requested flag 'popcnt' [0x00800000]
    
    A similar 'enforce' pseudo flag exists which in addition
    to the above causes qemu to error exit if requested flags are
    unavailable.
    
    Configuration data for a cpu model resides in the target config
    file which by default will be installed as:
    
        /usr/local/etc/qemu/target-<arch>.conf
    
    The format of this file should be self explanatory given the
    definitions for the above six models and essentially mimics
    the structure of the static x86_def_t x86_defs.
    
    Encoding of cpuid flags names now allows aliases for both the
    configuration file and the command line which reconciles some
    Intel/AMD/Linux/Qemu naming differences.
    
    This patch was tested relative to qemu.git.
    Signed-off-by: default avatarjohn cooper <john.cooper@redhat.com>
    Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
    b5ec5ce0
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