• Paul Mackerras's avatar
    KVM: PPC: Book3S: Controls for in-kernel sPAPR hypercall handling · 699a0ea0
    Paul Mackerras authored
    This provides a way for userspace controls which sPAPR hcalls get
    handled in the kernel.  Each hcall can be individually enabled or
    disabled for in-kernel handling, except for H_RTAS.  The exception
    for H_RTAS is because userspace can already control whether
    individual RTAS functions are handled in-kernel or not via the
    KVM_PPC_RTAS_DEFINE_TOKEN ioctl, and because the numeric value for
    H_RTAS is out of the normal sequence of hcall numbers.
    
    Hcalls are enabled or disabled using the KVM_ENABLE_CAP ioctl for the
    KVM_CAP_PPC_ENABLE_HCALL capability on the file descriptor for the VM.
    The args field of the struct kvm_enable_cap specifies the hcall number
    in args[0] and the enable/disable flag in args[1]; 0 means disable
    in-kernel handling (so that the hcall will always cause an exit to
    userspace) and 1 means enable.  Enabling or disabling in-kernel
    handling of an hcall is effective across the whole VM.
    
    The ability for KVM_ENABLE_CAP to be used on a VM file descriptor
    on PowerPC is new, added by this commit.  The KVM_CAP_ENABLE_CAP_VM
    capability advertises that this ability exists.
    
    When a VM is created, an initial set of hcalls are enabled for
    in-kernel handling.  The set that is enabled is the set that have
    an in-kernel implementation at this point.  Any new hcall
    implementations from this point onwards should not be added to the
    default set without a good reason.
    
    No distinction is made between real-mode and virtual-mode hcall
    implementations; the one setting controls them both.
    Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
    Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
    699a0ea0
book3s_pr_papr.c 9.09 KB