xen/cpuhotplug: Fix initial CPU offlining for PV(H) guests

Commit a926f81d2f6c ("xen/cpuhotplug: Replace cpu_up/down() with
device_online/offline()") replaced cpu_down() with device_offline()
call w

xen/cpuhotplug: Fix initial CPU offlining for PV(H) guests

Commit a926f81d2f6c ("xen/cpuhotplug: Replace cpu_up/down() with
device_online/offline()") replaced cpu_down() with device_offline()
call which requires that the CPU has been registered before. This
registration, however, happens later from topology_init() which
is called as subsys_initcall(). setup_vcpu_hotplug_event(), on the
other hand, is invoked earlier, during arch_initcall().

As result, booting a PV(H) guest with vcpus < maxvcpus causes a crash.

Move setup_vcpu_hotplug_event() (and therefore setup_cpu_watcher()) to
late_initcall(). In addition, instead of performing all offlining steps
in setup_cpu_watcher() simply call disable_hotplug_cpu().

Fixes: a926f81d2f6c (xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()"
Signed-off-by: Boris Ostrovsky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Juergen Gross <[email protected]>
Signed-off-by: Boris Ostrovsky <[email protected]>

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xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()

The core device API performs extra housekeeping bits that are missing
from directly calling cpu_up/down().

See commit a6717c01ddc2

xen/cpuhotplug: Replace cpu_up/down() with device_online/offline()

The core device API performs extra housekeeping bits that are missing
from directly calling cpu_up/down().

See commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and
serialization during LPM") for an example description of what might go
wrong.

This also prepares to make cpu_up/down() a private interface of the cpu
subsystem.

Signed-off-by: Qais Yousef <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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xen, cpu_hotplug: Prevent an out of bounds access

The "cpu" variable comes from the sscanf() so Smatch marks it as
untrusted data. We can't pass a higher value than "nr_cpu_ids" to
cpu_possible() o

xen, cpu_hotplug: Prevent an out of bounds access

The "cpu" variable comes from the sscanf() so Smatch marks it as
untrusted data. We can't pass a higher value than "nr_cpu_ids" to
cpu_possible() or it results in an out of bounds access.

Fixes: d68d82afd4c8 ("xen: implement CPU hotplugging")
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Signed-off-by: Juergen Gross <[email protected]>

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xen: avoid crash in disable_hotplug_cpu

The command 'xl vcpu-set 0 0', issued in dom0, will crash dom0:

BUG: unable to handle kernel NULL pointer dereference at 00000000000002d8
PGD 0 P4D 0
Oops: 0

xen: avoid crash in disable_hotplug_cpu

The command 'xl vcpu-set 0 0', issued in dom0, will crash dom0:

BUG: unable to handle kernel NULL pointer dereference at 00000000000002d8
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 7 PID: 65 Comm: xenwatch Not tainted 4.19.0-rc2-1.ga9462db-default #1 openSUSE Tumbleweed (unreleased)
Hardware name: Intel Corporation S5520UR/S5520UR, BIOS S5500.86B.01.00.0050.050620101605 05/06/2010
RIP: e030:device_offline+0x9/0xb0
Code: 77 24 00 e9 ce fe ff ff 48 8b 13 e9 68 ff ff ff 48 8b 13 e9 29 ff ff ff 48 8b 13 e9 ea fe ff ff 90 66 66 66 66 90 41 54 55 53 <f6> 87 d8 02 00 00 01 0f 85 88 00 00 00 48 c7 c2 20 09 60 81 31 f6
RSP: e02b:ffffc90040f27e80 EFLAGS: 00010203
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8801f3800000 RSI: ffffc90040f27e70 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff820e47b3 R09: 0000000000000000
R10: 0000000000007ff0 R11: 0000000000000000 R12: ffffffff822e6d30
R13: dead000000000200 R14: dead000000000100 R15: ffffffff8158b4e0
FS: 00007ffa595158c0(0000) GS:ffff8801f39c0000(0000) knlGS:0000000000000000
CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000002d8 CR3: 00000001d9602000 CR4: 0000000000002660
Call Trace:
handle_vcpu_hotplug_event+0xb5/0xc0
xenwatch_thread+0x80/0x140
? wait_woken+0x80/0x80
kthread+0x112/0x130
? kthread_create_worker_on_cpu+0x40/0x40
ret_from_fork+0x3a/0x50

This happens because handle_vcpu_hotplug_event is called twice. In the
first iteration cpu_present is still true, in the second iteration
cpu_present is false which causes get_cpu_device to return NULL.
In case of cpu#0, cpu_online is apparently always true.

Fix this crash by checking if the cpu can be hotplugged, which is false
for a cpu that was just removed.

Also check if the cpu was actually offlined by device_remove, otherwise
leave the cpu_present state as it is.

Rearrange to code to do all work with device_hotplug_lock held.

Signed-off-by: Olaf Hering <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Signed-off-by: Boris Ostrovsky <[email protected]>

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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xen: modify xenstore watch event interface

Today a Xenstore watch event is delivered via a callback function
declared as:

void (*callback)(struct xenbus_watch *,
const char **vec,

xen: modify xenstore watch event interface

Today a Xenstore watch event is delivered via a callback function
declared as:

void (*callback)(struct xenbus_watch *,
const char **vec, unsigned int len);

As all watch events only ever come with two parameters (path and token)
changing the prototype to:

void (*callback)(struct xenbus_watch *,
const char *path, const char *token);

is the natural thing to do.

Apply this change and adapt all users.

Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]

Signed-off-by: Juergen Gross <[email protected]>
Reviewed-by: Paul Durrant <[email protected]>
Reviewed-by: Wei Liu <[email protected]>
Reviewed-by: Roger Pau Monné <[email protected]>
Reviewed-by: Boris Ostrovsky <[email protected]>
Signed-off-by: Boris Ostrovsky <[email protected]>

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xen/pvh: Enable CPU hotplug

PVH guests don't (yet) receive ACPI hotplug interrupts and therefore
need to monitor xenstore for CPU hotplug event.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@orac

xen/pvh: Enable CPU hotplug

PVH guests don't (yet) receive ACPI hotplug interrupts and therefore
need to monitor xenstore for CPU hotplug event.

Signed-off-by: Boris Ostrovsky <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>

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xen, cpu_hotplug: call device_offline instead of cpu_down

When offlining a cpu, instead of cpu_down, call device_offline, which
also takes care of updating the cpu.dev.offline field. This keeps the

xen, cpu_hotplug: call device_offline instead of cpu_down

When offlining a cpu, instead of cpu_down, call device_offline, which
also takes care of updating the cpu.dev.offline field. This keeps the
sysfs file /sys/devices/system/cpu/cpuN/online, up to date. Also move
the call to disable_hotplug_cpu, because it makes more sense to have it
there.

We don't call device_online at cpu-hotplug time, because that would
immediately take the cpu online, while we want to retain the current
behaviour: the user needs to explicitly enable the cpu after it has
been hotplugged.

Signed-off-by: Stefano Stabellini <[email protected]>
Reviewed-by: Boris Ostrovsky <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]

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xen/arm: Enable cpu_hotplug.c

Build cpu_hotplug for ARM and ARM64 guests.

Rename arch_(un)register_cpu to xen_(un)register_cpu and provide an
empty implementation on ARM and ARM64. On x86 just call

xen/arm: Enable cpu_hotplug.c

Build cpu_hotplug for ARM and ARM64 guests.

Rename arch_(un)register_cpu to xen_(un)register_cpu and provide an
empty implementation on ARM and ARM64. On x86 just call
arch_(un)register_cpu as we are already doing.

Initialize cpu_hotplug on ARM.

Signed-off-by: Stefano Stabellini <[email protected]>
Reviewed-by: Julien Grall <[email protected]>
Reviewed-by: Boris Ostrovsky <[email protected]>

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xen: Convert printks to pr_<level>

Convert printks to pr_<level> (excludes printk(KERN_DEBUG...)
to be more consistent throughout the xen subsystem.

Add pr_fmt with KBUILD_MODNAME or "xen:" KBUILD_

xen: Convert printks to pr_<level>

Convert printks to pr_<level> (excludes printk(KERN_DEBUG...)
to be more consistent throughout the xen subsystem.

Add pr_fmt with KBUILD_MODNAME or "xen:" KBUILD_MODNAME
Coalesce formats and add missing word spaces
Add missing newlines
Align arguments and reflow to 80 columns
Remove DRV_NAME from formats as pr_fmt adds the same content

This does change some of the prefixes of these messages
but it also does make them more consistent.

Signed-off-by: Joe Perches <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>

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Xen: properly bound buffer access when parsing cpu/*/availability

At the same time reduce the local buffers to 16 bytes each.

Signed-off-by: Jan Beulich <[email protected]>
Signed-off-by: Konrad Rz

Xen: properly bound buffer access when parsing cpu/*/availability

At the same time reduce the local buffers to 16 bytes each.

Signed-off-by: Jan Beulich <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>

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xen/bootup: During bootup suppress XENBUS: Unable to read cpu state

When the initial domain starts, it prints (depending on the
amount of CPUs) a slew of
XENBUS: Unable to read cpu state
XENBUS: Una

xen/bootup: During bootup suppress XENBUS: Unable to read cpu state

When the initial domain starts, it prints (depending on the
amount of CPUs) a slew of
XENBUS: Unable to read cpu state
XENBUS: Unable to read cpu state
XENBUS: Unable to read cpu state
XENBUS: Unable to read cpu state

which provide no useful information - as the error is a valid
issue - but not on the initial domain. The reason is that the
XenStore is not accessible at that time (it is after all the
first guest) so the CPU hotplug watch cannot parse "availability/cpu"
attribute.

Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>

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xen: move Xen-testing predicates to common header

Move xen_domain and related tests out of asm-x86 to xen/xen.h so they
can be included whenever they are necessary.

Signed-off-by: Jeremy Fitzhardin

xen: move Xen-testing predicates to common header

Move xen_domain and related tests out of asm-x86 to xen/xen.h so they
can be included whenever they are necessary.

Signed-off-by: Jeremy Fitzhardinge <[email protected]>
Signed-off-by: Jesse Barnes <[email protected]>

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cpumask: Use modern cpumask style in Xen

Signed-off-by: Rusty Russell <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
LKML-Reference: <[email protected]

cpumask: Use modern cpumask style in Xen

Signed-off-by: Rusty Russell <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

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xen: honour VCPU availability on boot

If a VM is booted with offline VCPUs then unplug them during boot. Determining
the availability of a VCPU requires access to XenStore which is not available
at

xen: honour VCPU availability on boot

If a VM is booted with offline VCPUs then unplug them during boot. Determining
the availability of a VCPU requires access to XenStore which is not available
at the point smp_prepare_cpus() is called, therefore we bring up all VCPUS
initially and unplug the offline ones as soon as XenStore becomes available.

Signed-off-by: Ian Campbell <[email protected]>

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xen: honour VCPU availability on boot

If a VM is booted with offline VCPUs then unplug them during boot. Determining
the availability of a VCPU requires access to XenStore which is not available
at

xen: honour VCPU availability on boot

If a VM is booted with offline VCPUs then unplug them during boot. Determining
the availability of a VCPU requires access to XenStore which is not available
at the point smp_prepare_cpus() is called, therefore we bring up all VCPUS
initially and unplug the offline ones as soon as XenStore becomes available.

Signed-off-by: Ian Campbell <[email protected]>

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cpumask: make Xen use the new operators.

Impact: cleanup

In particular, *map are deprecated, and you have to use the accessors
as *mask are const.

Signed-off-by: Rusty Russell <[email protected].

cpumask: make Xen use the new operators.

Impact: cleanup

In particular, *map are deprecated, and you have to use the accessors
as *mask are const.

Signed-off-by: Rusty Russell <[email protected]>
To: Jeremy Fitzhardinge <[email protected]>

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x86, um: ... and asm-x86 move

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: H. Peter Anvin <[email protected]>

xen: compilation fix fo xen CPU hotplugging

This patch fixes compilation error on ia64.
include asm/xen/hypervisor.h instead of asm-x86/xen/hypervisor.h
use xen_pv_domain() instead of is_running_on_

xen: compilation fix fo xen CPU hotplugging

This patch fixes compilation error on ia64.
include asm/xen/hypervisor.h instead of asm-x86/xen/hypervisor.h
use xen_pv_domain() instead of is_running_on_xen()

> CC drivers/xen/cpu_hotplug.o
> In file included from /linux-2.6/drivers/xen/cpu_hotplug.c:5:
> /linux-2.6/include/asm-x86/xen/hypervisor.h:44:22: error: asm/desc.h: No such file or directory
> /linux-2.6/include/asm-x86/xen/hypervisor.h:66:1: warning: "MULTI_UVMFLAGS_INDEX" redefined
> In file included from /linux-2.6/include/asm-x86/xen/hypervisor.h:52,
> from /linux-2.6/drivers/xen/cpu_hotplug.c:5:
> /linux-2.6/arch/ia64/include/asm/xen/hypercall.h:233:1: warning: this is the location of the previous definition
> /linux-2.6/drivers/xen/cpu_hotplug.c: In function 'setup_vcpu_hotplug_event':
> /linux-2.6/drivers/xen/cpu_hotplug.c:81: error: implicit declaration of function 'is_running_on_xen'
> make[4]: *** [drivers/xen/cpu_hotplug.o] Error 1
> make[4]: *** Waiting for unfinished jobs....

Signed-off-by: Isaku Yamahata <[email protected]>
Signed-off-by: Jeremy Fitzhardinge <[email protected]>
Cc: Isaku Yamahata <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

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Xen: fix cpu_hotplug.c build by replacing is_running_on_xen() with xen_pv_domain()

Signed-off-by: Alex Nixon <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

xen: implement CPU hotplugging

Note the changes from 2.6.18-xen CPU hotplugging:

A vcpu_down request from the remote admin via Xenbus both hotunplugs the
CPU, and disables it by removing it from th

xen: implement CPU hotplugging

Note the changes from 2.6.18-xen CPU hotplugging:

A vcpu_down request from the remote admin via Xenbus both hotunplugs the
CPU, and disables it by removing it from the cpu_present map, and removing
its entry in /sys.

A vcpu_up request from the remote admin only re-enables the CPU, and does
not immediately bring the CPU up. A udev event is emitted, which can be
caught by the user if he wishes to automatically re-up CPUs when available,
or implement a more complex policy.

Signed-off-by: Alex Nixon <[email protected]>
Acked-by: Jeremy Fitzhardinge <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

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