€•*y      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ(/translations/zh_CN/virt/hyperv/overview”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/zh_TW/virt/hyperv/overview”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/it_IT/virt/hyperv/overview”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/ja_JP/virt/hyperv/overview”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/ko_KR/virt/hyperv/overview”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/sp_SP/virt/hyperv/overview”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ SPDX-License-Identifier: GPL-2.0”h]”hŒ SPDX-License-Identifier: GPL-2.0”…””}”hh£sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1h¡hhhžhhŸŒB/var/lib/git/docbuild/linux/Documentation/virt/hyperv/overview.rst”h KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒOverview”h]”hŒOverview”…””}”(hh»hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh¶hžhhŸh³h KubhŒ	paragraph”“”)”}”(hX  The Linux kernel contains a variety of code for running as a fully
enlightened guest on Microsoft's Hyper-V hypervisor.  Hyper-V
consists primarily of a bare-metal hypervisor plus a virtual machine
management service running in the parent partition (roughly
equivalent to KVM and QEMU, for example).  Guest VMs run in child
partitions.  In this documentation, references to Hyper-V usually
encompass both the hypervisor and the VMM service without making a
distinction about which functionality is provided by which
component.”h]”hX  The Linux kernel contains a variety of code for running as a fully
enlightened guest on Microsoftâ€™s Hyper-V hypervisor.  Hyper-V
consists primarily of a bare-metal hypervisor plus a virtual machine
management service running in the parent partition (roughly
equivalent to KVM and QEMU, for example).  Guest VMs run in child
partitions.  In this documentation, references to Hyper-V usually
encompass both the hypervisor and the VMM service without making a
distinction about which functionality is provided by which
component.”…””}”(hhËhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khh¶hžhubhÊ)”}”(hŒÇHyper-V runs on x86/x64 and arm64 architectures, and Linux guests
are supported on both.  The functionality and behavior of Hyper-V is
generally the same on both architectures unless noted otherwise.”h]”hŒÇHyper-V runs on x86/x64 and arm64 architectures, and Linux guests
are supported on both.  The functionality and behavior of Hyper-V is
generally the same on both architectures unless noted otherwise.”…””}”(hhÙhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khh¶hžhubhµ)”}”(hhh]”(hº)”}”(hŒ&Linux Guest Communication with Hyper-V”h]”hŒ&Linux Guest Communication with Hyper-V”…””}”(hhêhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hhçhžhhŸh³h KubhÊ)”}”(hŒ=Linux guests communicate with Hyper-V in four different ways:”h]”hŒ=Linux guests communicate with Hyper-V in four different ways:”…””}”(hhøhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KhhçhžhubhŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒßImplicit traps: As defined by the x86/x64 or arm64 architecture,
some guest actions trap to Hyper-V.  Hyper-V emulates the action and
returns control to the guest.  This behavior is generally invisible
to the Linux kernel.
”h]”hÊ)”}”(hŒÞImplicit traps: As defined by the x86/x64 or arm64 architecture,
some guest actions trap to Hyper-V.  Hyper-V emulates the action and
returns control to the guest.  This behavior is generally invisible
to the Linux kernel.”h]”hŒÞImplicit traps: As defined by the x86/x64 or arm64 architecture,
some guest actions trap to Hyper-V.  Hyper-V emulates the action and
returns control to the guest.  This behavior is generally invisible
to the Linux kernel.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  hžhhŸh³h Nubj  )”}”(hX‘  Explicit hypercalls: Linux makes an explicit function call to
Hyper-V, passing parameters.  Hyper-V performs the requested action
and returns control to the caller.  Parameters are passed in
processor registers or in memory shared between the Linux guest and
Hyper-V.   On x86/x64, hypercalls use a Hyper-V specific calling
sequence.  On arm64, hypercalls use the ARM standard SMCCC calling
sequence.
”h]”hÊ)”}”(hX  Explicit hypercalls: Linux makes an explicit function call to
Hyper-V, passing parameters.  Hyper-V performs the requested action
and returns control to the caller.  Parameters are passed in
processor registers or in memory shared between the Linux guest and
Hyper-V.   On x86/x64, hypercalls use a Hyper-V specific calling
sequence.  On arm64, hypercalls use the ARM standard SMCCC calling
sequence.”h]”hX  Explicit hypercalls: Linux makes an explicit function call to
Hyper-V, passing parameters.  Hyper-V performs the requested action
and returns control to the caller.  Parameters are passed in
processor registers or in memory shared between the Linux guest and
Hyper-V.   On x86/x64, hypercalls use a Hyper-V specific calling
sequence.  On arm64, hypercalls use the ARM standard SMCCC calling
sequence.”…””}”(hj)  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khj%  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  hžhhŸh³h Nubj  )”}”(hXM  Synthetic register access: Hyper-V implements a variety of
synthetic registers.  On x86/x64 these registers appear as MSRs in
the guest, and the Linux kernel can read or write these MSRs using
the normal mechanisms defined by the x86/x64 architecture.  On
arm64, these synthetic registers must be accessed using explicit
hypercalls.
”h]”hÊ)”}”(hXL  Synthetic register access: Hyper-V implements a variety of
synthetic registers.  On x86/x64 these registers appear as MSRs in
the guest, and the Linux kernel can read or write these MSRs using
the normal mechanisms defined by the x86/x64 architecture.  On
arm64, these synthetic registers must be accessed using explicit
hypercalls.”h]”hXL  Synthetic register access: Hyper-V implements a variety of
synthetic registers.  On x86/x64 these registers appear as MSRs in
the guest, and the Linux kernel can read or write these MSRs using
the normal mechanisms defined by the x86/x64 architecture.  On
arm64, these synthetic registers must be accessed using explicit
hypercalls.”…””}”(hjA  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K$hj=  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  hžhhŸh³h Nubj  )”}”(hX  VMBus: VMBus is a higher-level software construct that is built on
the other 3 mechanisms.  It is a message passing interface between
the Hyper-V host and the Linux guest.  It uses memory that is shared
between Hyper-V and the guest, along with various signaling
mechanisms.
”h]”hÊ)”}”(hX  VMBus: VMBus is a higher-level software construct that is built on
the other 3 mechanisms.  It is a message passing interface between
the Hyper-V host and the Linux guest.  It uses memory that is shared
between Hyper-V and the guest, along with various signaling
mechanisms.”h]”hX  VMBus: VMBus is a higher-level software construct that is built on
the other 3 mechanisms.  It is a message passing interface between
the Hyper-V host and the Linux guest.  It uses memory that is shared
between Hyper-V and the guest, along with various signaling
mechanisms.”…””}”(hjY  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K+hjU  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  hžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ*”uh1j  hŸh³h KhhçhžhubhÊ)”}”(hX  The first three communication mechanisms are documented in the
`Hyper-V Top Level Functional Spec (TLFS)`_.  The TLFS describes
general Hyper-V functionality and provides details on the hypercalls
and synthetic registers.  The TLFS is currently written for the
x86/x64 architecture only.”h]”(hŒ?The first three communication mechanisms are documented in the
”…””}”(hju  hžhhŸNh NubhŒ	reference”“”)”}”(hŒ+`Hyper-V Top Level Functional Spec (TLFS)`_”h]”hŒ(Hyper-V Top Level Functional Spec (TLFS)”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œname”Œ(Hyper-V Top Level Functional Spec (TLFS)”Œrefuri”ŒLhttps://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/tlfs”uh1j}  hju  Œresolved”KubhŒµ.  The TLFS describes
general Hyper-V functionality and provides details on the hypercalls
and synthetic registers.  The TLFS is currently written for the
x86/x64 architecture only.”…””}”(hju  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K1hhçhžhubhŒtarget”“”)”}”(hŒz.. _Hyper-V Top Level Functional Spec (TLFS): https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/tlfs”h]”h}”(h]”Œ&hyper-v-top-level-functional-spec-tlfs”ah ]”h"]”Œ(hyper-v top level functional spec (tlfs)”ah$]”h&]”j  j  uh1jœ  h K7hhçhžhhŸh³Œ
referenced”KubhÊ)”}”(hŒ›VMBus is not documented.  This documentation provides a high-level
overview of VMBus and how it works, but the details can be discerned
only from the code.”h]”hŒ›VMBus is not documented.  This documentation provides a high-level
overview of VMBus and how it works, but the details can be discerned
only from the code.”…””}”(hj«  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K9hhçhžhubeh}”(h]”Œ&linux-guest-communication-with-hyper-v”ah ]”h"]”Œ&linux guest communication with hyper-v”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒSharing Memory”h]”hŒSharing Memory”…””}”(hjÄ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjÁ  hžhhŸh³h K>ubhÊ)”}”(hŒ‰Many aspects are communication between Hyper-V and Linux are based
on sharing memory.  Such sharing is generally accomplished as
follows:”h]”hŒ‰Many aspects are communication between Hyper-V and Linux are based
on sharing memory.  Such sharing is generally accomplished as
follows:”…””}”(hjÒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K?hjÁ  hžhubj  )”}”(hhh]”(j  )”}”(hŒXLinux allocates memory from its physical address space using
standard Linux mechanisms.
”h]”hÊ)”}”(hŒWLinux allocates memory from its physical address space using
standard Linux mechanisms.”h]”hŒWLinux allocates memory from its physical address space using
standard Linux mechanisms.”…””}”(hjç  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KChjã  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjà  hžhhŸh³h Nubj  )”}”(hXÕ  Linux tells Hyper-V the guest physical address (GPA) of the
allocated memory.  Many shared areas are kept to 1 page so that a
single GPA is sufficient.   Larger shared areas require a list of
GPAs, which usually do not need to be contiguous in the guest
physical address space.  How Hyper-V is told about the GPA or list
of GPAs varies.  In some cases, a single GPA is written to a
synthetic register.  In other cases, a GPA or list of GPAs is sent
in a VMBus message.
”h]”hÊ)”}”(hXÔ  Linux tells Hyper-V the guest physical address (GPA) of the
allocated memory.  Many shared areas are kept to 1 page so that a
single GPA is sufficient.   Larger shared areas require a list of
GPAs, which usually do not need to be contiguous in the guest
physical address space.  How Hyper-V is told about the GPA or list
of GPAs varies.  In some cases, a single GPA is written to a
synthetic register.  In other cases, a GPA or list of GPAs is sent
in a VMBus message.”h]”hXÔ  Linux tells Hyper-V the guest physical address (GPA) of the
allocated memory.  Many shared areas are kept to 1 page so that a
single GPA is sufficient.   Larger shared areas require a list of
GPAs, which usually do not need to be contiguous in the guest
physical address space.  How Hyper-V is told about the GPA or list
of GPAs varies.  In some cases, a single GPA is written to a
synthetic register.  In other cases, a GPA or list of GPAs is sent
in a VMBus message.”…””}”(hjÿ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KFhjû  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjà  hžhhŸh³h Nubj  )”}”(hŒ‡Hyper-V translates the GPAs into "real" physical memory addresses,
and creates a virtual mapping that it can use to access the memory.
”h]”hÊ)”}”(hŒ†Hyper-V translates the GPAs into "real" physical memory addresses,
and creates a virtual mapping that it can use to access the memory.”h]”hŒŠHyper-V translates the GPAs into â€œrealâ€ physical memory addresses,
and creates a virtual mapping that it can use to access the memory.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KOhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjà  hžhhŸh³h Nubj  )”}”(hŒoLinux can later revoke sharing it has previously established by
telling Hyper-V to set the shared GPA to zero.
”h]”hÊ)”}”(hŒnLinux can later revoke sharing it has previously established by
telling Hyper-V to set the shared GPA to zero.”h]”hŒnLinux can later revoke sharing it has previously established by
telling Hyper-V to set the shared GPA to zero.”…””}”(hj/  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KRhj+  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjà  hžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”js  jt  uh1j  hŸh³h KChjÁ  hžhubhÊ)”}”(hXv  Hyper-V operates with a page size of 4 Kbytes. GPAs communicated to
Hyper-V may be in the form of page numbers, and always describe a
range of 4 Kbytes.  Since the Linux guest page size on x86/x64 is
also 4 Kbytes, the mapping from guest page to Hyper-V page is 1-to-1.
On arm64, Hyper-V supports guests with 4/16/64 Kbyte pages as
defined by the arm64 architecture.   If Linux is using 16 or 64
Kbyte pages, Linux code must be careful to communicate with Hyper-V
only in terms of 4 Kbyte pages.  HV_HYP_PAGE_SIZE and related macros
are used in code that communicates with Hyper-V so that it works
correctly in all configurations.”h]”hXv  Hyper-V operates with a page size of 4 Kbytes. GPAs communicated to
Hyper-V may be in the form of page numbers, and always describe a
range of 4 Kbytes.  Since the Linux guest page size on x86/x64 is
also 4 Kbytes, the mapping from guest page to Hyper-V page is 1-to-1.
On arm64, Hyper-V supports guests with 4/16/64 Kbyte pages as
defined by the arm64 architecture.   If Linux is using 16 or 64
Kbyte pages, Linux code must be careful to communicate with Hyper-V
only in terms of 4 Kbyte pages.  HV_HYP_PAGE_SIZE and related macros
are used in code that communicates with Hyper-V so that it works
correctly in all configurations.”…””}”(hjI  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KUhjÁ  hžhubhÊ)”}”(hXc  As described in the TLFS, a few memory pages shared between Hyper-V
and the Linux guest are "overlay" pages.  With overlay pages, Linux
uses the usual approach of allocating guest memory and telling
Hyper-V the GPA of the allocated memory.  But Hyper-V then replaces
that physical memory page with a page it has allocated, and the
original physical memory page is no longer accessible in the guest
VM.  Linux may access the memory normally as if it were the memory
that it originally allocated.  The "overlay" behavior is visible
only because the contents of the page (as seen by Linux) change at
the time that Linux originally establishes the sharing and the
overlay page is inserted.  Similarly, the contents change if Linux
revokes the sharing, in which case Hyper-V removes the overlay page,
and the guest page originally allocated by Linux becomes visible
again.”h]”hXk  As described in the TLFS, a few memory pages shared between Hyper-V
and the Linux guest are â€œoverlayâ€ pages.  With overlay pages, Linux
uses the usual approach of allocating guest memory and telling
Hyper-V the GPA of the allocated memory.  But Hyper-V then replaces
that physical memory page with a page it has allocated, and the
original physical memory page is no longer accessible in the guest
VM.  Linux may access the memory normally as if it were the memory
that it originally allocated.  The â€œoverlayâ€ behavior is visible
only because the contents of the page (as seen by Linux) change at
the time that Linux originally establishes the sharing and the
overlay page is inserted.  Similarly, the contents change if Linux
revokes the sharing, in which case Hyper-V removes the overlay page,
and the guest page originally allocated by Linux becomes visible
again.”…””}”(hjW  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K`hjÁ  hžhubhÊ)”}”(hX«  Before Linux does a kexec to a kdump kernel or any other kernel,
memory shared with Hyper-V should be revoked.  Hyper-V could modify
a shared page or remove an overlay page after the new kernel is
using the page for a different purpose, corrupting the new kernel.
Hyper-V does not provide a single "set everything" operation to
guest VMs, so Linux code must individually revoke all sharing before
doing kexec.   See hv_kexec_handler() and hv_crash_handler().  But
the crash/panic path still has holes in cleanup because some shared
pages are set using per-CPU synthetic registers and there's no
mechanism to revoke the shared pages for CPUs other than the CPU
running the panic path.”h]”hX±  Before Linux does a kexec to a kdump kernel or any other kernel,
memory shared with Hyper-V should be revoked.  Hyper-V could modify
a shared page or remove an overlay page after the new kernel is
using the page for a different purpose, corrupting the new kernel.
Hyper-V does not provide a single â€œset everythingâ€ operation to
guest VMs, so Linux code must individually revoke all sharing before
doing kexec.   See hv_kexec_handler() and hv_crash_handler().  But
the crash/panic path still has holes in cleanup because some shared
pages are set using per-CPU synthetic registers and thereâ€™s no
mechanism to revoke the shared pages for CPUs other than the CPU
running the panic path.”…””}”(hje  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KohjÁ  hžhubeh}”(h]”Œsharing-memory”ah ]”h"]”Œsharing memory”ah$]”h&]”uh1h´hh¶hžhhŸh³h K>ubhµ)”}”(hhh]”(hº)”}”(hŒCPU Management”h]”hŒCPU Management”…””}”(hj~  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj{  hžhhŸh³h K|ubhÊ)”}”(hX  Hyper-V does not have a ability to hot-add or hot-remove a CPU
from a running VM.  However, Windows Server 2019 Hyper-V and
earlier versions may provide guests with ACPI tables that indicate
more CPUs than are actually present in the VM.  As is normal, Linux
treats these additional CPUs as potential hot-add CPUs, and reports
them as such even though Hyper-V will never actually hot-add them.
Starting in Windows Server 2022 Hyper-V, the ACPI tables reflect
only the CPUs actually present in the VM, so Linux does not report
any hot-add CPUs.”h]”hX  Hyper-V does not have a ability to hot-add or hot-remove a CPU
from a running VM.  However, Windows Server 2019 Hyper-V and
earlier versions may provide guests with ACPI tables that indicate
more CPUs than are actually present in the VM.  As is normal, Linux
treats these additional CPUs as potential hot-add CPUs, and reports
them as such even though Hyper-V will never actually hot-add them.
Starting in Windows Server 2022 Hyper-V, the ACPI tables reflect
only the CPUs actually present in the VM, so Linux does not report
any hot-add CPUs.”…””}”(hjŒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K}hj{  hžhubhÊ)”}”(hX  A Linux guest CPU may be taken offline using the normal Linux
mechanisms, provided no VMBus channel interrupts are assigned to
the CPU.  See the section on VMBus Interrupts for more details
on how VMBus channel interrupts can be re-assigned to permit
taking a CPU offline.”h]”hX  A Linux guest CPU may be taken offline using the normal Linux
mechanisms, provided no VMBus channel interrupts are assigned to
the CPU.  See the section on VMBus Interrupts for more details
on how VMBus channel interrupts can be re-assigned to permit
taking a CPU offline.”…””}”(hjš  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K‡hj{  hžhubeh}”(h]”Œcpu-management”ah ]”h"]”Œcpu management”ah$]”h&]”uh1h´hh¶hžhhŸh³h K|ubhµ)”}”(hhh]”(hº)”}”(hŒ32-bit and 64-bit”h]”hŒ32-bit and 64-bit”…””}”(hj³  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj°  hžhhŸh³h KŽubhÊ)”}”(hŒÒOn x86/x64, Hyper-V supports 32-bit and 64-bit guests, and Linux
will build and run in either version. While the 32-bit version is
expected to work, it is used rarely and may suffer from undetected
regressions.”h]”hŒÒOn x86/x64, Hyper-V supports 32-bit and 64-bit guests, and Linux
will build and run in either version. While the 32-bit version is
expected to work, it is used rarely and may suffer from undetected
regressions.”…””}”(hjÁ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khj°  hžhubhÊ)”}”(hŒ.On arm64, Hyper-V supports only 64-bit guests.”h]”hŒ.On arm64, Hyper-V supports only 64-bit guests.”…””}”(hjÏ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K”hj°  hžhubeh}”(h]”Œbit-and-64-bit”ah ]”h"]”Œ32-bit and 64-bit”ah$]”h&]”uh1h´hh¶hžhhŸh³h KŽubhµ)”}”(hhh]”(hº)”}”(hŒEndian-ness”h]”hŒEndian-ness”…””}”(hjè  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjå  hžhhŸh³h K—ubhÊ)”}”(hŒõAll communication between Hyper-V and guest VMs uses Little-Endian
format on both x86/x64 and arm64.  Big-endian format on arm64 is not
supported by Hyper-V, and Linux code does not use endian-ness macros
when accessing data shared with Hyper-V.”h]”hŒõAll communication between Hyper-V and guest VMs uses Little-Endian
format on both x86/x64 and arm64.  Big-endian format on arm64 is not
supported by Hyper-V, and Linux code does not use endian-ness macros
when accessing data shared with Hyper-V.”…””}”(hjö  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K˜hjå  hžhubeh}”(h]”Œendian-ness”ah ]”h"]”Œendian-ness”ah$]”h&]”uh1h´hh¶hžhhŸh³h K—ubhµ)”}”(hhh]”(hº)”}”(hŒ
Versioning”h]”hŒ
Versioning”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj  hžhhŸh³h KžubhÊ)”}”(hŒÐCurrent Linux kernels operate correctly with older versions of
Hyper-V back to Windows Server 2012 Hyper-V. Support for running
on the original Hyper-V release in Windows Server 2008/2008 R2
has been removed.”h]”hŒÐCurrent Linux kernels operate correctly with older versions of
Hyper-V back to Windows Server 2012 Hyper-V. Support for running
on the original Hyper-V release in Windows Server 2008/2008 R2
has been removed.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KŸhj  hžhubhÊ)”}”(hX¬  A Linux guest on Hyper-V outputs in dmesg the version of Hyper-V
it is running on.  This version is in the form of a Windows build
number and is for display purposes only. Linux code does not
test this version number at runtime to determine available features
and functionality. Hyper-V indicates feature/function availability
via flags in synthetic MSRs that Hyper-V provides to the guest,
and the guest code tests these flags.”h]”hX¬  A Linux guest on Hyper-V outputs in dmesg the version of Hyper-V
it is running on.  This version is in the form of a Windows build
number and is for display purposes only. Linux code does not
test this version number at runtime to determine available features
and functionality. Hyper-V indicates feature/function availability
via flags in synthetic MSRs that Hyper-V provides to the guest,
and the guest code tests these flags.”…””}”(hj+  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K¤hj  hžhubhÊ)”}”(hX  VMBus has its own protocol version that is negotiated during the
initial VMBus connection from the guest to Hyper-V. This version
number is also output to dmesg during boot.  This version number
is checked in a few places in the code to determine if specific
functionality is present.”h]”hX  VMBus has its own protocol version that is negotiated during the
initial VMBus connection from the guest to Hyper-V. This version
number is also output to dmesg during boot.  This version number
is checked in a few places in the code to determine if specific
functionality is present.”…””}”(hj9  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K¬hj  hžhubhÊ)”}”(hX2  Furthermore, each synthetic device on VMBus also has a protocol
version that is separate from the VMBus protocol version. Device
drivers for these synthetic devices typically negotiate the device
protocol version, and may test that protocol version to determine
if specific device functionality is present.”h]”hX2  Furthermore, each synthetic device on VMBus also has a protocol
version that is separate from the VMBus protocol version. Device
drivers for these synthetic devices typically negotiate the device
protocol version, and may test that protocol version to determine
if specific device functionality is present.”…””}”(hjG  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K²hj  hžhubeh}”(h]”Œ
versioning”ah ]”h"]”Œ
versioning”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kžubhµ)”}”(hhh]”(hº)”}”(hŒCode Packaging”h]”hŒCode Packaging”…””}”(hj`  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj]  hžhhŸh³h K¹ubhÊ)”}”(hŒOHyper-V related code appears in the Linux kernel code tree in three
main areas:”h]”hŒOHyper-V related code appears in the Linux kernel code tree in three
main areas:”…””}”(hjn  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kºhj]  hžhubhŒenumerated_list”“”)”}”(hhh]”(j  )”}”(hŒdrivers/hv
”h]”hÊ)”}”(hŒ
drivers/hv”h]”hŒ
drivers/hv”…””}”(hj…  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K½hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj~  hžhhŸh³h Nubj  )”}”(hŒ&arch/x86/hyperv and arch/arm64/hyperv
”h]”hÊ)”}”(hŒ%arch/x86/hyperv and arch/arm64/hyperv”h]”hŒ%arch/x86/hyperv and arch/arm64/hyperv”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K¿hj™  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj~  hžhhŸh³h Nubj  )”}”(hŒ\individual device driver areas such as drivers/scsi, drivers/net,
drivers/clocksource, etc.
”h]”hÊ)”}”(hŒ[individual device driver areas such as drivers/scsi, drivers/net,
drivers/clocksource, etc.”h]”hŒ[individual device driver areas such as drivers/scsi, drivers/net,
drivers/clocksource, etc.”…””}”(hjµ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÁhj±  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj~  hžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œenumtype”Œarabic”Œprefix”hŒsuffix”Œ.”uh1j|  hj]  hžhhŸh³h K½ubhÊ)”}”(hŒ°A few miscellaneous files appear elsewhere. See the full list under
"Hyper-V/Azure CORE AND DRIVERS" and "DRM DRIVER FOR HYPERV
SYNTHETIC VIDEO DEVICE" in the MAINTAINERS file.”h]”hŒ¸A few miscellaneous files appear elsewhere. See the full list under
â€œHyper-V/Azure CORE AND DRIVERSâ€ and â€œDRM DRIVER FOR HYPERV
SYNTHETIC VIDEO DEVICEâ€ in the MAINTAINERS file.”…””}”(hjÔ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÄhj]  hžhubhÊ)”}”(hŒœThe code in #1 and #2 is built only when CONFIG_HYPERV is set.
Similarly, the code for most Hyper-V related drivers is built only
when CONFIG_HYPERV is set.”h]”hŒœThe code in #1 and #2 is built only when CONFIG_HYPERV is set.
Similarly, the code for most Hyper-V related drivers is built only
when CONFIG_HYPERV is set.”…””}”(hjâ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÈhj]  hžhubhÊ)”}”(hŒáMost Hyper-V related code in #1 and #3 can be built as a module.
The architecture specific code in #2 must be built-in.  Also,
drivers/hv/hv_common.c is low-level code that is common across
architectures and must be built-in.”h]”hŒáMost Hyper-V related code in #1 and #3 can be built as a module.
The architecture specific code in #2 must be built-in.  Also,
drivers/hv/hv_common.c is low-level code that is common across
architectures and must be built-in.”…””}”(hjð  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÌhj]  hžhubeh}”(h]”Œcode-packaging”ah ]”h"]”Œcode packaging”ah$]”h&]”uh1h´hh¶hžhhŸh³h K¹ubeh}”(h]”Œoverview”ah ]”h"]”Œoverview”ah$]”h&]”uh1h´hhhžhhŸh³h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h³uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¹NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”j1  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h³Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œ(hyper-v top level functional spec (tlfs)”]”j  asŒrefids”}”Œnameids”}”(j  j  j¾  j»  j§  j¤  jx  ju  j­  jª  jâ  jß  j	  j  jZ  jW  j  j   uŒ	nametypes”}”(j  ‰j¾  ‰j§  ˆjx  ‰j­  ‰jâ  ‰j	  ‰jZ  ‰j  ‰uh}”(j  h¶j»  hçj¤  jž  ju  jÁ  jª  j{  jß  j°  j  jå  jW  j  j   j]  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.