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author | Christoph Hellwig <hch@lst.de> | 2019-07-24 10:24:49 +0300 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-07-24 11:52:11 +0300 |
commit | 2f5947dfcaecb99f2dd559156eecbeb7b95e4c02 (patch) | |
tree | a16db9103d69f0d5fae6de67987a1f1476f4598b /Documentation/virt/paravirt_ops.rst | |
parent | c6bf2ae931adbd3e10967e12142856439a211813 (diff) | |
download | linux-2f5947dfcaecb99f2dd559156eecbeb7b95e4c02.tar.xz |
Documentation: move Documentation/virtual to Documentation/virt
Renaming docs seems to be en vogue at the moment, so fix on of the
grossly misnamed directories. We usually never use "virtual" as
a shortcut for virtualization in the kernel, but always virt,
as seen in the virt/ top-level directory. Fix up the documentation
to match that.
Fixes: ed16648eb5b8 ("Move kvm, uml, and lguest subdirectories under a common "virtual" directory, I.E:")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virt/paravirt_ops.rst')
-rw-r--r-- | Documentation/virt/paravirt_ops.rst | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/Documentation/virt/paravirt_ops.rst b/Documentation/virt/paravirt_ops.rst new file mode 100644 index 000000000000..6b789d27cead --- /dev/null +++ b/Documentation/virt/paravirt_ops.rst @@ -0,0 +1,35 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============ +Paravirt_ops +============ + +Linux provides support for different hypervisor virtualization technologies. +Historically different binary kernels would be required in order to support +different hypervisors, this restriction was removed with pv_ops. +Linux pv_ops is a virtualization API which enables support for different +hypervisors. It allows each hypervisor to override critical operations and +allows a single kernel binary to run on all supported execution environments +including native machine -- without any hypervisors. + +pv_ops provides a set of function pointers which represent operations +corresponding to low level critical instructions and high level +functionalities in various areas. pv-ops allows for optimizations at run +time by enabling binary patching of the low-ops critical operations +at boot time. + +pv_ops operations are classified into three categories: + +- simple indirect call + These operations correspond to high level functionality where it is + known that the overhead of indirect call isn't very important. + +- indirect call which allows optimization with binary patch + Usually these operations correspond to low level critical instructions. They + are called frequently and are performance critical. The overhead is + very important. + +- a set of macros for hand written assembly code + Hand written assembly codes (.S files) also need paravirtualization + because they include sensitive instructions or some of code paths in + them are very performance critical. |