• James Hogan's avatar
    KVM: MIPS: Use CP0_BadInstr[P] for emulation · 6a97c775
    James Hogan authored
    When exiting from the guest, store the values of the CP0_BadInstr and
    CP0_BadInstrP registers if they exist, which contain the encodings of
    the instructions which caused the last synchronous exception.
    
    When the instruction is needed for emulation, kvm_get_badinstr() and
    kvm_get_badinstrp() are used instead of calling kvm_get_inst() directly,
    to decide whether to read the saved CP0_BadInstr/CP0_BadInstrP registers
    (if they exist), or read the instruction from memory (if not).
    
    The use of these registers should be more robust than using
    kvm_get_inst(), as it actually gives the instruction encoding seen by
    the hardware rather than relying on user accessors after the fact, which
    can be fooled by incoherent icache or a racing code modification. It
    will also work with VZ, where the guest virtual memory isn't directly
    accessible by the host with user accessors.
    Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: "Radim Krčmář" <rkrcmar@redhat.com>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: linux-mips@linux-mips.org
    Cc: kvm@vger.kernel.org
    6a97c775
entry.c 22.6 KB