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  • Andrew Jones's avatar
    KVM: arm/arm64: Only skip MMIO insn once · 2113c5f6
    Andrew Jones authored
    If after an MMIO exit to userspace a VCPU is immediately run with an
    immediate_exit request, such as when a signal is delivered or an MMIO
    emulation completion is needed, then the VCPU completes the MMIO
    emulation and immediately returns to userspace. As the exit_reason
    does not get changed from KVM_EXIT_MMIO in these cases we have to
    be careful not to complete the MMIO emulation again, when the VCPU is
    eventually run again, because the emulation does an instruction skip
    (and doing too many skips would be a waste of guest code :-) We need
    to use additional VCPU state to track if the emulation is complete.
    As luck would have it, we already have 'mmio_needed', which even
    appears to be used in this way by other architectures already.
    Fixes: 0d640732
     ("arm64: KVM: Skip MMIO insn after emulation")
    Acked-by: default avatarMark Rutland <>
    Signed-off-by: default avatarAndrew Jones <>
    Signed-off-by: default avatarMarc Zyngier <>