• Suresh Warrier's avatar
    KVM: PPC: Book3S HV: Complete passthrough interrupt in host · f7af5209
    Suresh Warrier authored
    In existing real mode ICP code, when updating the virtual ICP
    state, if there is a required action that cannot be completely
    handled in real mode, as for instance, a VCPU needs to be woken
    up, flags are set in the ICP to indicate the required action.
    This is checked when returning from hypercalls to decide whether
    the call needs switch back to the host where the action can be
    performed in virtual mode. Note that if h_ipi_redirect is enabled,
    real mode code will first try to message a free host CPU to
    complete this job instead of returning the host to do it ourselves.
    
    Currently, the real mode PCI passthrough interrupt handling code
    checks if any of these flags are set and simply returns to the host.
    This is not good enough as the trap value (0x500) is treated as an
    external interrupt by the host code. It is only when the trap value
    is a hypercall that the host code searches for and acts on unfinished
    work by calling kvmppc_xics_rm_complete.
    
    This patch introduces a special trap BOOK3S_INTERRUPT_HV_RM_HARD
    which is returned by KVM if there is unfinished business to be
    completed in host virtual mode after handling a PCI passthrough
    interrupt. The host checks for this special interrupt condition
    and calls into the kvmppc_xics_rm_complete, which is made an
    exported function for this reason.
    
    [paulus@ozlabs.org - moved logic to set r12 to BOOK3S_INTERRUPT_HV_RM_HARD
     in book3s_hv_rmhandlers.S into the end of kvmppc_check_wake_reason.]
    Signed-off-by: default avatarSuresh Warrier <warrier@linux.vnet.ibm.com>
    Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
    f7af5209
book3s_hv_builtin.c 11.4 KB