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authorAlexander Graf <agraf@suse.de>2011-08-31 12:58:55 +0400
committerAvi Kivity <avi@redhat.com>2011-09-25 20:52:31 +0400
commit821246a5a548858c78a5e8860862e91c9e035d6b (patch)
tree0d1a5744da3cf6aab958f20e86b76fbbb95306e4 /Documentation/virtual
parent19ccb76a1938ab364a412253daec64613acbf3df (diff)
downloadlinux-821246a5a548858c78a5e8860862e91c9e035d6b.tar.xz
KVM: Update documentation to include detailed ENABLE_CAP description
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@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/kvm/api.txt47
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 2d510b6a649a..7945b0bd35e2 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1653,3 +1653,50 @@ 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 capability 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.