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Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Move the bpf verifier trace check into the new switch statement in HEAD. Resolve the overlapping changes in hinic, where bug fixes overlap the addition of VF support. Signed-off-by: David S. Miller <[email protected]>
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arm/index | ||
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devices/index | ||
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running-nested-guests |
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============================== | ||
Running nested guests with KVM | ||
============================== | ||
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A nested guest is the ability to run a guest inside another guest (it | ||
can be KVM-based or a different hypervisor). The straightforward | ||
example is a KVM guest that in turn runs on a KVM guest (the rest of | ||
this document is built on this example):: | ||
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.----------------. .----------------. | ||
| | | | | ||
| L2 | | L2 | | ||
| (Nested Guest) | | (Nested Guest) | | ||
| | | | | ||
|----------------'--'----------------| | ||
| | | ||
| L1 (Guest Hypervisor) | | ||
| KVM (/dev/kvm) | | ||
| | | ||
.------------------------------------------------------. | ||
| L0 (Host Hypervisor) | | ||
| KVM (/dev/kvm) | | ||
|------------------------------------------------------| | ||
| Hardware (with virtualization extensions) | | ||
'------------------------------------------------------' | ||
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Terminology: | ||
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- L0 – level-0; the bare metal host, running KVM | ||
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- L1 – level-1 guest; a VM running on L0; also called the "guest | ||
hypervisor", as it itself is capable of running KVM. | ||
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- L2 – level-2 guest; a VM running on L1, this is the "nested guest" | ||
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.. note:: The above diagram is modelled after the x86 architecture; | ||
s390x, ppc64 and other architectures are likely to have | ||
a different design for nesting. | ||
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For example, s390x always has an LPAR (LogicalPARtition) | ||
hypervisor running on bare metal, adding another layer and | ||
resulting in at least four levels in a nested setup — L0 (bare | ||
metal, running the LPAR hypervisor), L1 (host hypervisor), L2 | ||
(guest hypervisor), L3 (nested guest). | ||
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This document will stick with the three-level terminology (L0, | ||
L1, and L2) for all architectures; and will largely focus on | ||
x86. | ||
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Use Cases | ||
--------- | ||
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There are several scenarios where nested KVM can be useful, to name a | ||
few: | ||
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- As a developer, you want to test your software on different operating | ||
systems (OSes). Instead of renting multiple VMs from a Cloud | ||
Provider, using nested KVM lets you rent a large enough "guest | ||
hypervisor" (level-1 guest). This in turn allows you to create | ||
multiple nested guests (level-2 guests), running different OSes, on | ||
which you can develop and test your software. | ||
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- Live migration of "guest hypervisors" and their nested guests, for | ||
load balancing, disaster recovery, etc. | ||
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- VM image creation tools (e.g. ``virt-install``, etc) often run | ||
their own VM, and users expect these to work inside a VM. | ||
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- Some OSes use virtualization internally for security (e.g. to let | ||
applications run safely in isolation). | ||
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Enabling "nested" (x86) | ||
----------------------- | ||
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From Linux kernel v4.19 onwards, the ``nested`` KVM parameter is enabled | ||
by default for Intel and AMD. (Though your Linux distribution might | ||
override this default.) | ||
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In case you are running a Linux kernel older than v4.19, to enable | ||
nesting, set the ``nested`` KVM module parameter to ``Y`` or ``1``. To | ||
persist this setting across reboots, you can add it in a config file, as | ||
shown below: | ||
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1. On the bare metal host (L0), list the kernel modules and ensure that | ||
the KVM modules:: | ||
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$ lsmod | grep -i kvm | ||
kvm_intel 133627 0 | ||
kvm 435079 1 kvm_intel | ||
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2. Show information for ``kvm_intel`` module:: | ||
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$ modinfo kvm_intel | grep -i nested | ||
parm: nested:bool | ||
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3. For the nested KVM configuration to persist across reboots, place the | ||
below in ``/etc/modprobed/kvm_intel.conf`` (create the file if it | ||
doesn't exist):: | ||
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$ cat /etc/modprobe.d/kvm_intel.conf | ||
options kvm-intel nested=y | ||
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4. Unload and re-load the KVM Intel module:: | ||
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$ sudo rmmod kvm-intel | ||
$ sudo modprobe kvm-intel | ||
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5. Verify if the ``nested`` parameter for KVM is enabled:: | ||
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$ cat /sys/module/kvm_intel/parameters/nested | ||
Y | ||
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For AMD hosts, the process is the same as above, except that the module | ||
name is ``kvm-amd``. | ||
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Additional nested-related kernel parameters (x86) | ||
------------------------------------------------- | ||
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If your hardware is sufficiently advanced (Intel Haswell processor or | ||
higher, which has newer hardware virt extensions), the following | ||
additional features will also be enabled by default: "Shadow VMCS | ||
(Virtual Machine Control Structure)", APIC Virtualization on your bare | ||
metal host (L0). Parameters for Intel hosts:: | ||
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$ cat /sys/module/kvm_intel/parameters/enable_shadow_vmcs | ||
Y | ||
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$ cat /sys/module/kvm_intel/parameters/enable_apicv | ||
Y | ||
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$ cat /sys/module/kvm_intel/parameters/ept | ||
Y | ||
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.. note:: If you suspect your L2 (i.e. nested guest) is running slower, | ||
ensure the above are enabled (particularly | ||
``enable_shadow_vmcs`` and ``ept``). | ||
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Starting a nested guest (x86) | ||
----------------------------- | ||
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Once your bare metal host (L0) is configured for nesting, you should be | ||
able to start an L1 guest with:: | ||
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$ qemu-kvm -cpu host [...] | ||
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The above will pass through the host CPU's capabilities as-is to the | ||
gues); or for better live migration compatibility, use a named CPU | ||
model supported by QEMU. e.g.:: | ||
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$ qemu-kvm -cpu Haswell-noTSX-IBRS,vmx=on | ||
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then the guest hypervisor will subsequently be capable of running a | ||
nested guest with accelerated KVM. | ||
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Enabling "nested" (s390x) | ||
------------------------- | ||
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1. On the host hypervisor (L0), enable the ``nested`` parameter on | ||
s390x:: | ||
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$ rmmod kvm | ||
$ modprobe kvm nested=1 | ||
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.. note:: On s390x, the kernel parameter ``hpage`` is mutually exclusive | ||
with the ``nested`` paramter — i.e. to be able to enable | ||
``nested``, the ``hpage`` parameter *must* be disabled. | ||
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2. The guest hypervisor (L1) must be provided with the ``sie`` CPU | ||
feature — with QEMU, this can be done by using "host passthrough" | ||
(via the command-line ``-cpu host``). | ||
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3. Now the KVM module can be loaded in the L1 (guest hypervisor):: | ||
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$ modprobe kvm | ||
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Live migration with nested KVM | ||
------------------------------ | ||
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Migrating an L1 guest, with a *live* nested guest in it, to another | ||
bare metal host, works as of Linux kernel 5.3 and QEMU 4.2.0 for | ||
Intel x86 systems, and even on older versions for s390x. | ||
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On AMD systems, once an L1 guest has started an L2 guest, the L1 guest | ||
should no longer be migrated or saved (refer to QEMU documentation on | ||
"savevm"/"loadvm") until the L2 guest shuts down. Attempting to migrate | ||
or save-and-load an L1 guest while an L2 guest is running will result in | ||
undefined behavior. You might see a ``kernel BUG!`` entry in ``dmesg``, a | ||
kernel 'oops', or an outright kernel panic. Such a migrated or loaded L1 | ||
guest can no longer be considered stable or secure, and must be restarted. | ||
Migrating an L1 guest merely configured to support nesting, while not | ||
actually running L2 guests, is expected to function normally even on AMD | ||
systems but may fail once guests are started. | ||
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Migrating an L2 guest is always expected to succeed, so all the following | ||
scenarios should work even on AMD systems: | ||
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- Migrating a nested guest (L2) to another L1 guest on the *same* bare | ||
metal host. | ||
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- Migrating a nested guest (L2) to another L1 guest on a *different* | ||
bare metal host. | ||
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- Migrating a nested guest (L2) to a bare metal host. | ||
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Reporting bugs from nested setups | ||
----------------------------------- | ||
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Debugging "nested" problems can involve sifting through log files across | ||
L0, L1 and L2; this can result in tedious back-n-forth between the bug | ||
reporter and the bug fixer. | ||
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- Mention that you are in a "nested" setup. If you are running any kind | ||
of "nesting" at all, say so. Unfortunately, this needs to be called | ||
out because when reporting bugs, people tend to forget to even | ||
*mention* that they're using nested virtualization. | ||
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- Ensure you are actually running KVM on KVM. Sometimes people do not | ||
have KVM enabled for their guest hypervisor (L1), which results in | ||
them running with pure emulation or what QEMU calls it as "TCG", but | ||
they think they're running nested KVM. Thus confusing "nested Virt" | ||
(which could also mean, QEMU on KVM) with "nested KVM" (KVM on KVM). | ||
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Information to collect (generic) | ||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | ||
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The following is not an exhaustive list, but a very good starting point: | ||
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- Kernel, libvirt, and QEMU version from L0 | ||
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- Kernel, libvirt and QEMU version from L1 | ||
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- QEMU command-line of L1 -- when using libvirt, you'll find it here: | ||
``/var/log/libvirt/qemu/instance.log`` | ||
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- QEMU command-line of L2 -- as above, when using libvirt, get the | ||
complete libvirt-generated QEMU command-line | ||
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- ``cat /sys/cpuinfo`` from L0 | ||
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- ``cat /sys/cpuinfo`` from L1 | ||
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- ``lscpu`` from L0 | ||
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- ``lscpu`` from L1 | ||
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- Full ``dmesg`` output from L0 | ||
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- Full ``dmesg`` output from L1 | ||
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x86-specific info to collect | ||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | ||
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Both the below commands, ``x86info`` and ``dmidecode``, should be | ||
available on most Linux distributions with the same name: | ||
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- Output of: ``x86info -a`` from L0 | ||
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- Output of: ``x86info -a`` from L1 | ||
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- Output of: ``dmidecode`` from L0 | ||
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- Output of: ``dmidecode`` from L1 | ||
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s390x-specific info to collect | ||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | ||
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Along with the earlier mentioned generic details, the below is | ||
also recommended: | ||
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- ``/proc/sysinfo`` from L1; this will also include the info from L0 |
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|
@@ -3936,24 +3936,20 @@ F: arch/powerpc/platforms/cell/ | |
CEPH COMMON CODE (LIBCEPH) | ||
M: Ilya Dryomov <[email protected]> | ||
M: Jeff Layton <[email protected]> | ||
M: Sage Weil <[email protected]> | ||
L: [email protected] | ||
S: Supported | ||
W: http://ceph.com/ | ||
T: git git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git | ||
T: git git://github.com/ceph/ceph-client.git | ||
F: include/linux/ceph/ | ||
F: include/linux/crush/ | ||
F: net/ceph/ | ||
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CEPH DISTRIBUTED FILE SYSTEM CLIENT (CEPH) | ||
M: Jeff Layton <[email protected]> | ||
M: Sage Weil <[email protected]> | ||
M: Ilya Dryomov <[email protected]> | ||
L: [email protected] | ||
S: Supported | ||
W: http://ceph.com/ | ||
T: git git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git | ||
T: git git://github.com/ceph/ceph-client.git | ||
F: Documentation/filesystems/ceph.rst | ||
F: fs/ceph/ | ||
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@@ -7119,9 +7115,10 @@ F: include/uapi/asm-generic/ | |
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GENERIC PHY FRAMEWORK | ||
M: Kishon Vijay Abraham I <[email protected]> | ||
M: Vinod Koul <[email protected]> | ||
L: [email protected] | ||
S: Supported | ||
T: git git://git.kernel.org/pub/scm/linux/kernel/git/kishon/linux-phy.git | ||
T: git git://git.kernel.org/pub/scm/linux/kernel/git/phy/linux-phy.git | ||
F: Documentation/devicetree/bindings/phy/ | ||
F: drivers/phy/ | ||
F: include/linux/phy/ | ||
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@@ -7746,11 +7743,6 @@ L: [email protected] | |
S: Orphan | ||
F: drivers/platform/x86/tc1100-wmi.c | ||
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HP100: Driver for HP 10/100 Mbit/s Voice Grade Network Adapter Series | ||
M: Jaroslav Kysela <[email protected]> | ||
S: Obsolete | ||
F: drivers/staging/hp/hp100.* | ||
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HPET: High Precision Event Timers driver | ||
M: Clemens Ladisch <[email protected]> | ||
S: Maintained | ||
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@@ -11718,8 +11710,9 @@ F: net/core/drop_monitor.c | |
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NETWORKING DRIVERS | ||
M: "David S. Miller" <[email protected]> | ||
M: Jakub Kicinski <[email protected]> | ||
L: [email protected] | ||
S: Odd Fixes | ||
S: Maintained | ||
W: http://www.linuxfoundation.org/en/Net | ||
Q: http://patchwork.ozlabs.org/project/netdev/list/ | ||
T: git git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git | ||
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@@ -14102,12 +14095,10 @@ F: drivers/media/radio/radio-tea5777.c | |
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RADOS BLOCK DEVICE (RBD) | ||
M: Ilya Dryomov <[email protected]> | ||
M: Sage Weil <[email protected]> | ||
R: Dongsheng Yang <[email protected]> | ||
L: [email protected] | ||
S: Supported | ||
W: http://ceph.com/ | ||
T: git git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git | ||
T: git git://github.com/ceph/ceph-client.git | ||
F: Documentation/ABI/testing/sysfs-bus-rbd | ||
F: drivers/block/rbd.c | ||
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@@ -14644,6 +14635,7 @@ F: drivers/iommu/s390-iommu.c | |
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S390 IUCV NETWORK LAYER | ||
M: Julian Wiedmann <[email protected]> | ||
M: Karsten Graul <[email protected]> | ||
M: Ursula Braun <[email protected]> | ||
L: [email protected] | ||
S: Supported | ||
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@@ -14654,6 +14646,7 @@ F: net/iucv/ | |
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S390 NETWORK DRIVERS | ||
M: Julian Wiedmann <[email protected]> | ||
M: Karsten Graul <[email protected]> | ||
M: Ursula Braun <[email protected]> | ||
L: [email protected] | ||
S: Supported | ||
|
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