Il 25/04/2014 17:19, James Hogan ha scritto:
Expose the KVM guest CP0_Count bias (from the monotonic kernel time) to userland in nanosecond units via a new KVM_REG_MIPS_COUNT_BIAS register accessible with the KVM_{GET,SET}_ONE_REG ioctls. This gives userland control of the bias so that it can exactly match its own monotonic time.The nanosecond bias is stored separately from the raw bias used internally (since nanoseconds isn't a convenient or efficient unit for various timer calculations), and is recalculated each time the raw count bias is altered. The raw count bias used in CP0_Count determination is recalculated when the nanosecond bias is altered via the KVM_SET_ONE_REG ioctl. Signed-off-by: James Hogan <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Gleb Natapov <[email protected]> Cc: [email protected] Cc: Ralf Baechle <[email protected]> Cc: [email protected] Cc: David Daney <[email protected]> Cc: Sanjay Lal <[email protected]>
If it is possible and not too hairy to use a raw value in userspace (together with KVM_REG_MIPS_COUNT_HZ), please do it---my suggestions were just that, a suggestion. Otherwise, the patch looks good.
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