• Laurent Vivier's avatar
    KVM: Add coalesced MMIO support (common part) · 5f94c174
    Laurent Vivier authored
    This patch adds all needed structures to coalesce MMIOs.
    Until an architecture uses it, it is not compiled.
    
    Coalesced MMIO introduces two ioctl() to define where are the MMIO zones that
    can be coalesced:
    
    - KVM_REGISTER_COALESCED_MMIO registers a coalesced MMIO zone.
      It requests one parameter (struct kvm_coalesced_mmio_zone) which defines
      a memory area where MMIOs can be coalesced until the next switch to
      user space. The maximum number of MMIO zones is KVM_COALESCED_MMIO_ZONE_MAX.
    
    - KVM_UNREGISTER_COALESCED_MMIO cancels all registered zones inside
      the given bounds (bounds are also given by struct kvm_coalesced_mmio_zone).
    
    The userspace client can check kernel coalesced MMIO availability by asking
    ioctl(KVM_CHECK_EXTENSION) for the KVM_CAP_COALESCED_MMIO capability.
    The ioctl() call to KVM_CAP_COALESCED_MMIO will return 0 if not supported,
    or the page offset where will be stored the ring buffer.
    The page offset depends on the architecture.
    
    After an ioctl(KVM_RUN), the first page of the KVM memory mapped points to
    a kvm_run structure. The offset given by KVM_CAP_COALESCED_MMIO is
    an offset to the coalesced MMIO ring expressed in PAGE_SIZE relatively
    to the address of the start of th kvm_run structure. The MMIO ring buffer
    is defined by the structure kvm_coalesced_mmio_ring.
    
    [akio: fix oops during guest shutdown]
    Signed-off-by: default avatarLaurent Vivier <Laurent.Vivier@bull.net>
    Signed-off-by: default avatarAkio Takebe <takebe_akio@jp.fujitsu.com>
    Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
    5f94c174
kvm_main.c 33.8 KB