We have an ioctl that enables capabilities individually, but no description on what exactly happens when we enable a capability using this ioctl. This patch adds documentation for capability enabling in a new section of the API documentation. Signed-off-by: Alexander Graf <agraf@xxxxxxx> --- Documentation/virtual/kvm/api.txt | 48 +++++++++++++++++++++++++++++++++++++ 1 files changed, 48 insertions(+), 0 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 2d510b6..8757366 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1653,3 +1653,51 @@ developer registration required to access it). char padding[256]; }; }; + +6. Capabilities that can be enabled + +There are certain capabilities that change the behavior of the virtual CPU when +enabled. To enable them, please see section 4.37. Below you can find a list of +capabilities and what their effect on the vCPU is when enabling them. + +The following information is provided along with the description: + + Architectures: which instruction set architectures provide this ioctl. + x86 includes both i386 and x86_64. + + Parameters: what parameters are accepted by the capability. + + Returns: the return value. General error numbers (EBADF, ENOMEM, EINVAL) + are not detailed, but errors with specific meanings are. + +6.1 KVM_CAP_PPC_OSI + +Architectures: ppc +Parameters: none +Returns: 0 on success; -1 on error + +This capaobility enables interception of OSI hypercalls that otherwise would +be treated as normal system calls to be injected into the guest. OSI hypercalls +were invented by Mac-on-Linux to have a standardized communication mechanism +between the guest and the host. + +When this capability is enabled, KVM_EXIT_OSI can occur. + +6.2 KVM_CAP_PPC_PAPR + +Architectures: ppc +Parameters: none +Returns: 0 on success; -1 on error + +This capability enables interception of PAPR hypercalls. PAPR hypercalls are +done using the hypercall instruction "sc 1". + +It also sets the guest privilege level to "supervisor" mode. Usually the guest +runs in "hypervisor" privilege mode with a few missing features. + +In addition to the above, it changes the semantics of SDR1. In this mode, the +HTAB address part of SDR1 contains an HVA instead of a GPA, as PAPR keeps the +HTAB invisible to the guest. + +When this capability is enabled, KVM_EXIT_PAPR_HCALL can occur. + -- 1.6.0.2 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
