• David Hildenbrand's avatar
    KVM: s390: vsie: initial support for nested virtualization · a3508fbe
    David Hildenbrand authored
    This patch adds basic support for nested virtualization on s390x, called
    VSIE (virtual SIE) and allows it to be used by the guest if the necessary
    facilities are supported by the hardware and enabled for the guest.
    In order to make this work, we have to shadow the sie control block
    provided by guest 2. In order to gain some performance, we have to
    reuse the same shadow blocks as good as possible. For now, we allow
    as many shadow blocks as we have VCPUs (that way, every VCPU can run the
    VSIE concurrently).
    We have to watch out for the prefix getting unmapped out of our shadow
    gmap and properly get the VCPU out of VSIE in that case, to fault the
    prefix pages back in. We use the PROG_REQUEST bit for that purpose.
    This patch is based on an initial prototype by Tobias Elpelt.
    Acked-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
    Signed-off-by: default avatarDavid Hildenbrand <dahi@linux.vnet.ibm.com>
    Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>