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Diffstat (limited to 'Documentation/virt/paravirt_ops.rst')
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diff --git a/Documentation/virt/paravirt_ops.rst b/Documentation/virt/paravirt_ops.rst new file mode 100644 index 0000000000..62d867e0d4 --- /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-level 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 code paths in + them are very performance critical. |