Commit Graph

26 Commits

Author SHA1 Message Date
Jiasheng Jiang cbd5458ef1 xen: Fix implicit type conversion
The variable 'i' is defined as UINT. However, in the for_each_possible_cpu
its value is assigned to -1. That doesn't make sense and in the
cpumask_next() it is implicitly type converted to INT. It is universally
accepted that the implicit type conversion is terrible. Also, having the
good programming custom will set an example for others. Thus, it might be
better to change the definition of 'i' from UINT to INT.

[boris: fixed commit message formatting]

Fixes: 3fac10145b ("xen: Re-upload processor PM data to hypervisor after S3 resume (v2)")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Link: https://lore.kernel.org/r/1635233531-2437704-1-git-send-email-jiasheng@iscas.ac.cn
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jiamei Xie <jiamei.xie@arm.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-11-02 07:45:44 -05:00
Kees Cook 43135df0d7 xen: Replace lkml.org links with lore
As started by commit 05a5f51ca5 ("Documentation: Replace lkml.org
links with lore"), replace lkml.org links with lore to better use a
single source that's more likely to stay available long-term.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20210210234618.2734785-1-keescook@chromium.org
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2021-02-23 10:08:07 -06:00
Thomas Gleixner 2025cf9e19 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms and conditions of the gnu general public license
  version 2 as published by the free software foundation this program
  is distributed in the hope it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 263 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.208660670@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:36:37 +02:00
Andy Shevchenko 85eb278c18 xen/ACPI: Switch to bitmap_zalloc()
Switch to bitmap_zalloc() to show clearly what we are allocating.
Besides that it returns pointer of bitmap type instead of opaque void *.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
2019-03-04 15:04:39 +01:00
Jan Beulich 166deb0f0b xen/ACPI: don't upload Px/Cx data for disabled processors
This is unnecessary and triggers a warning in the hypervisor.

Often systems have more processor entries in their ACPI tables than are
actually installed/active. The ACPI_STA_DEVICE_PRESENT bit cannot be
reliably used, but the ACPI_MADT_ENABLED bit can. In order to not
introduce new functions in the main ACPI processor driver code, simply
use acpi_get_phys_id(), which does more than we need, but which checks
the MADT enabled bit in the process. Any CPU for which we can't
determine the APIC ID is unlikely to work properly anyway, so the extra
checks done by acpi_get_phys_id() should do no harm.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-08-20 14:46:18 -04:00
Dan Carpenter c37a3c9477 xen/acpi: off by one in read_acpi_id()
If acpi_id is == nr_acpi_bits, then we access one element beyond the end
of the acpi_psd[] array or we set one bit beyond the end of the bit map
when we do __set_bit(acpi_id, acpi_id_present);

Fixes: 59a5680291 ("xen/acpi-processor: C and P-state driver that uploads said data to hypervisor.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-03-30 11:30:13 -04:00
Joao Martins 4d0f1ce695 xen/acpi: upload _PSD info for non Dom0 CPUs too
All uploaded PM data from non-dom0 CPUs takes the info from vCPU 0 and
changing only the acpi_id. For processors which P-state coordination type
is HW_ALL (0xFD) it is OK to upload bogus P-state dependency information
(_PSD), because Xen will ignore any cpufreq domains created for past CPUs.

Albeit for platforms which expose coordination types as SW_ANY or SW_ALL,
this will have some unintended side effects. Effectively, it will look at
the P-state domain existence and *if it already exists* it will skip the
acpi-cpufreq initialization and thus inherit the policy from the first CPU
in the cpufreq domain. This will finally lead to the original cpu not
changing target freq to P0 other than the first in the domain. Which will
make turbo boost not getting enabled (e.g. for 'performance' governor) for
all cpus.

This patch fixes that, by also evaluating _PSD when we enumerate all ACPI
processors and thus always uploading the correct info to Xen. We export
acpi_processor_get_psd() for that this purpose, but change signature
to not assume an existent of acpi_processor given that ACPI isn't creating
an acpi_processor for non-dom0 CPUs.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2018-03-21 08:29:13 -04:00
Ankur Arora 1914f0cd20 xen/acpi: upload PM state from init-domain to Xen
This was broken in commit cd979883b9 ("xen/acpi-processor:
fix enabling interrupts on syscore_resume"). do_suspend (from
xen/manage.c) and thus xen_resume_notifier never get called on
the initial-domain at resume (it is if running as guest.)

The rationale for the breaking change was that upload_pm_data()
potentially does blocking work in syscore_resume(). This patch
addresses the original issue by scheduling upload_pm_data() to
execute in workqueue context.

Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: stable@vger.kernel.org
Based-on-patch-by: Konrad Wilk <konrad.wilk@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-03-23 12:00:02 -04:00
Ankur Arora 1c2593cc8f xen/acpi: Replace hard coded "ACPI0007"
Replace hard coded "ACPI0007" with ACPI_PROCESSOR_DEVICE_HID

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-03-23 09:42:15 -04:00
Jan Beulich 6f2d9d9921 xen/acpi: allow xen-acpi-processor driver to load on Xen 4.7
As of Xen 4.7 PV CPUID doesn't expose either of CPUID[1].ECX[7] and
CPUID[0x80000007].EDX[7] anymore, causing the driver to fail to load on
both Intel and AMD systems. Doing any kind of hardware capability
checks in the driver as a prerequisite was wrong anyway: With the
hypervisor being in charge, all such checking should be done by it. If
ACPI data gets uploaded despite some missing capability, the hypervisor
is free to ignore part or all of that data.

Ditch the entire check_prereq() function, and do the only valid check
(xen_initial_domain()) in the caller in its place.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
2016-07-08 14:53:13 +01:00
Stefano Stabellini cfafae9403 xen: rename dom0_op to platform_op
The dom0_op hypercall has been renamed to platform_op since Xen 3.2,
which is ancient, and modern upstream Linux kernels cannot run as dom0
and it anymore anyway.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2015-12-21 14:40:55 +00:00
Rafael J. Wysocki b2f8dc4ce6 ACPI / processor: Drop an unused argument of a cleanup routine
acpi_processor_unregister_performance() actually doesn't use its
first argument, so drop it and update the callers accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2015-07-22 22:11:16 +02:00
Konrad Rzeszutek Wilk 1a4b50f674 xen-acpi-processor: Don't display errors when we get -ENOSYS
which is a perfectly legal error. This can be triggered if the
user has booted Xen with the no-cpuidle parameter.

Reported-by-and-Tested-by: Don Slutz <dslutz@verizon.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2014-05-23 12:34:00 -04:00
Stanislaw Gruszka cd979883b9 xen/acpi-processor: fix enabling interrupts on syscore_resume
syscore->resume() callback is expected to do not enable interrupts,
it generates warning like below otherwise:

[ 9386.365390] WARNING: CPU: 0 PID: 6733 at drivers/base/syscore.c:104 syscore_resume+0x9a/0xe0()
[ 9386.365403] Interrupts enabled after xen_acpi_processor_resume+0x0/0x34 [xen_acpi_processor]
...
[ 9386.365429] Call Trace:
[ 9386.365434]  [<ffffffff81667a8b>] dump_stack+0x45/0x56
[ 9386.365437]  [<ffffffff8106921d>] warn_slowpath_common+0x7d/0xa0
[ 9386.365439]  [<ffffffff8106928c>] warn_slowpath_fmt+0x4c/0x50
[ 9386.365442]  [<ffffffffa0261bb0>] ? xen_upload_processor_pm_data+0x300/0x300 [xen_acpi_processor]
[ 9386.365443]  [<ffffffff814055fa>] syscore_resume+0x9a/0xe0
[ 9386.365445]  [<ffffffff810aef42>] suspend_devices_and_enter+0x402/0x470
[ 9386.365447]  [<ffffffff810af128>] pm_suspend+0x178/0x260

On xen_acpi_processor_resume() we call various procedures, which are
non atomic and can enable interrupts. To prevent the issue introduce
separate resume notify called after we enable interrupts on resume
and before we call other drivers resume callbacks.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2014-03-18 14:40:20 +00:00
Lv Zheng 8b48463f89 ACPI: Clean up inclusions of ACPI header files
Replace direct inclusions of <acpi/acpi.h>, <acpi/acpi_bus.h> and
<acpi/acpi_drivers.h>, which are incorrect, with <linux/acpi.h>
inclusions and remove some inclusions of those files that aren't
necessary.

First of all, <acpi/acpi.h>, <acpi/acpi_bus.h> and <acpi/acpi_drivers.h>
should not be included directly from any files that are built for
CONFIG_ACPI unset, because that generally leads to build warnings about
undefined symbols in !CONFIG_ACPI builds.  For CONFIG_ACPI set,
<linux/acpi.h> includes those files and for CONFIG_ACPI unset it
provides stub ACPI symbols to be used in that case.

Second, there are ordering dependencies between those files that always
have to be met.  Namely, it is required that <acpi/acpi_bus.h> be included
prior to <acpi/acpi_drivers.h> so that the acpi_pci_root declarations the
latter depends on are always there.  And <acpi/acpi.h> which provides
basic ACPICA type declarations should always be included prior to any other
ACPI headers in CONFIG_ACPI builds.  That also is taken care of including
<linux/acpi.h> as appropriate.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com> (drivers/pci stuff)
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> (Xen stuff)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-12-07 01:03:14 +01:00
Joe Perches 283c0972d5 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 <joe@perches.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-06-28 11:19:58 -04:00
Ben Guthro 18c0025b69 xen: resolve section mismatch warnings in xen-acpi-processor
The following resolves a section mismatch warning below in xen-acpi-processor introduced by
3fac10145b [13/13] xen: Re-upload processor PM data to hypervisor after S3 resume (v2)

Warning:
WARNING: drivers/xen/built-in.o(.text+0x2056a): Section mismatch in reference from the function xen_upload_processor_pm_data() to the function .init.text:read_acpi_id()
   The function xen_upload_processor_pm_data() references
   the function __init read_acpi_id().
   This is often because xen_upload_processor_pm_data lacks a __init
   annotation or the annotation of read_acpi_id is wrong.

Reported-by: kbuild test robot <fengguang.wu@intel.com>

Signed-off-by: Ben Guthro <benjamin.guthro@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-04-19 10:44:23 -04:00
Ben Guthro 3fac10145b xen: Re-upload processor PM data to hypervisor after S3 resume (v2)
Upon resume, it was found that ACPI C-states were missing from non-boot CPUs.
This change registers a syscore_ops handler for this case, and re-uploads the
PM information to the hypervisor to properly reset the C-state on these
processors.

v2:
v1 did not go through the check_acpi_ids() code-path, and missed some cases when
xen was running with the dom0_max_vcpus= command line parameter.

Signed-Off-By: Ben Guthro <benjamin.guthro@citrix.com>
[v3: Ate some tabs, s/printk/pr_info/]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-04-17 10:43:56 -04:00
Konrad Rzeszutek Wilk 949dd8c14f xen/acpi-processor: Don't dereference struct acpi_processor on all CPUs.
With git commit c705c78c0d
"acpi: Export the acpi_processor_get_performance_info" we are now
using a different mechanism to access the P-states.

The acpi_processor per-cpu structure is set and filtered by the
core ACPI code which shrinks the per_cpu contents to only online CPUs.
In the past we would call acpi_processor_register_performance()
which would have not tried to dereference offline cpus.

With the new patch and the fact that the loop we take is for
for_all_possible_cpus we end up crashing on some machines.
We could modify the loop to be for online_cpus - but all the other
loops in the code use possible_cpus (for a good reason) - so lets
leave it as so and just check if per_cpu(processor) is NULL.

With this patch we will bypass the !online but possible CPUs.
This fixes:

IP: [<ffffffffa00d13b5>] xen_acpi_processor_init+0x1b6/0xe01 [xen_acpi_processor]
PGD 4126e6067 PUD 4126e3067 PMD 0
Oops: 0002 [#1] SMP
Pid: 432, comm: modprobe Not tainted 3.9.0-rc3+ #28 To be filled by O.E.M. To be filled by O.E.M./M5A97
RIP: e030:[<ffffffffa00d13b5>]  [<ffffffffa00d13b5>] xen_acpi_processor_init+0x1b6/0xe01 [xen_acpi_processor]
RSP: e02b:ffff88040c8a3ce8  EFLAGS: 00010282
.. snip..
Call Trace:
 [<ffffffffa00d11ff>] ? read_acpi_id+0x12b/0x12b [xen_acpi_processor]
 [<ffffffff8100215a>] do_one_initcall+0x12a/0x180
 [<ffffffff810c42c3>] load_module+0x1cd3/0x2870
 [<ffffffff81319b70>] ? ddebug_proc_open+0xc0/0xc0
 [<ffffffff810c4f37>] sys_init_module+0xd7/0x120
 [<ffffffff8166ce19>] system_call_fastpath+0x16/0x1b

on some machines.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-03-22 08:23:11 -04:00
Konrad Rzeszutek Wilk c705c78c0d acpi: Export the acpi_processor_get_performance_info
The git commit d5aaffa9dd
(cpufreq: handle cpufreq being disabled for all exported function)
tightens the cpufreq API by returning errors when disable_cpufreq()
had been called.

The problem we are hitting is that the module xen-acpi-processor which
uses the ACPI's functions: acpi_processor_register_performance,
acpi_processor_preregister_performance, and acpi_processor_notify_smm
fails at acpi_processor_register_performance with -22.

Note that earlier during bootup in arch/x86/xen/setup.c there is also
an call to cpufreq's API: disable_cpufreq().

This is b/c we want the Linux kernel to parse the ACPI data, but leave
the cpufreq decisions to the hypervisor.

In v3.9 all the checks that d5aaffa9dd
added are now hit and the calls to cpufreq_register_notifier will now
fail. This means that acpi_processor_ppc_init ends up printing:

"Warning: Processor Platform Limit not supported"

and the acpi_processor_ppc_status is not set.

The repercussions of that is that the call to
acpi_processor_register_performance fails right away at:

	if (!(acpi_processor_ppc_status & PPC_REGISTERED))

and we don't progress any further on parsing and extracting the _P*
objects.

The only reason the Xen code called that function was b/c it was
exported and the only way to gather the P-states. But we can also
just make acpi_processor_get_performance_info be exported and not
use acpi_processor_register_performance. This patch does so.

Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-03-06 10:00:34 -05:00
Daniel Lezcano c59687f846 cpuidle / ACPI : remove power from acpi_processor_cx structure
Remove the unused power field from struct struct acpi_processor_cx.

[rjw: Modified changelog.]

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2012-09-05 15:13:48 +02:00
Konrad Rzeszutek Wilk 17f9b896b0 xen/acpi: Fix potential memory leak.
Coverity points out that we do not free in one case the
pr_backup - and sure enough we forgot.

Found by Coverity (CID 401970)

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-07-19 15:51:42 -04:00
H. Peter Anvin 323f90a608 xen-acpi-processor: Add missing #include <xen/xen.h>
This file depends on <xen/xen.h>, but the dependency was hidden due
to: <asm/acpi.h> -> <asm/trampoline.h> -> <asm/io.h> -> <xen/xen.h>

With the removal of <asm/trampoline.h>, this exposed the missing

Reported-by: Ingo Molnar <mingo@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2012-05-17 10:03:02 -07:00
Konrad Rzeszutek Wilk b930fe5e1f xen/acpi: Workaround broken BIOSes exporting non-existing C-states.
We did a similar check for the P-states but did not do it for
the C-states. What we want to do is ignore cases where the DSDT
has definition for sixteen CPUs, but the machine only has eight
CPUs and we get:
xen-acpi-processor: (CX): Hypervisor error (-22) for ACPI CPU14

Reported-by: Tobias Geiger <tobias.geiger@vido.info>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-04-26 22:07:28 -04:00
Konrad Rzeszutek Wilk 27257fc07c xen/acpi: Remove the WARN's as they just create noise.
When booting the kernel under machines that do not have P-states
we would end up with:

------------[ cut here ]------------
 WARNING: at drivers/xen/xen-acpi-processor.c:504
 xen_acpi_processor_init+0x286/0
 x2e0()
 Hardware name: ProLiant BL460c G6
 Modules linked in:
 Pid: 1, comm: swapper Not tainted 2.6.39-200.0.3.el5uek #1
 Call Trace:
  [<ffffffff8191d056>] ? xen_acpi_processor_init+0x286/0x2e0
  [<ffffffff81068300>] warn_slowpath_common+0x90/0xc0
  [<ffffffff8191cdd0>] ? check_acpi_ids+0x1e0/0x1e0
  [<ffffffff8106834a>] warn_slowpath_null+0x1a/0x20
  [<ffffffff8191d056>] xen_acpi_processor_init+0x286/0x2e0
  [<ffffffff8191cdd0>] ? check_acpi_ids+0x1e0/0x1e0
  [<ffffffff81002168>] do_one_initcall+0xe8/0x130

.. snip..

Which is OK - the machines do not have P-states, so we fail to register
to process the _PXX states. But there is no need to WARN the user
of it.

Oracle BZ# 13871288
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-03-21 12:17:22 -04:00
Konrad Rzeszutek Wilk 59a5680291 xen/acpi-processor: C and P-state driver that uploads said data to hypervisor.
This driver solves three problems:
 1). Parse and upload ACPI0007 (or PROCESSOR_TYPE) information to the
     hypervisor - aka P-states (cpufreq data).
 2). Upload the the Cx state information (cpuidle data).
 3). Inhibit CPU frequency scaling drivers from loading.

The reason for wanting to solve 1) and 2) is such that the Xen hypervisor
is the only one that knows the CPU usage of different guests and can
make the proper decision of when to put CPUs and packages in proper states.
Unfortunately the hypervisor has no support to parse ACPI DSDT tables, hence it
needs help from the initial domain to provide this information. The reason
for 3) is that we do not want the initial domain to change P-states while the
hypervisor is doing it as well - it causes rather some funny cases of P-states
transitions.

For this to work, the driver parses the Power Management data and uploads said
information to the Xen hypervisor. It also calls acpi_processor_notify_smm()
to inhibit the other CPU frequency scaling drivers from being loaded.

Everything revolves around the 'struct acpi_processor' structure which
gets updated during the bootup cycle in different stages. At the startup, when
the ACPI parser starts, the C-state information is processed (processor_idle)
and saved in said structure as 'power' element. Later on, the CPU frequency
scaling driver (powernow-k8 or acpi_cpufreq), would call the the
acpi_processor_* (processor_perflib functions) to parse P-states information
and populate in the said structure the 'performance' element.

Since we do not want the CPU frequency scaling drivers from loading
we have to call the acpi_processor_* functions to parse the P-states and
call "acpi_processor_notify_smm" to stop them from loading.

There is also one oddity in this driver which is that under Xen, the
physical online CPU count can be different from the virtual online CPU count.
Meaning that the macros 'for_[online|possible]_cpu' would process only
up to virtual online CPU count. We on the other hand want to process
the full amount of physical CPUs. For that, the driver checks if the ACPI IDs
count is different from the APIC ID count - which can happen if the user
choose to use dom0_max_vcpu argument. In such a case a backup of the PM
structure is used and uploaded to the hypervisor.

[v1-v2: Initial RFC implementations that were posted]
[v3: Changed the name to passthru suggested by Pasi Kärkkäinen <pasik@iki.fi>]
[v4: Added vCPU != pCPU support - aka dom0_max_vcpus support]
[v5: Cleaned up the driver, fix bug under Athlon XP]
[v6: Changed the driver to a CPU frequency governor]
[v7: Jan Beulich <jbeulich@suse.com> suggestion to make it a cpufreq scaling driver
     made me rework it as driver that inhibits cpufreq scaling driver]
[v8: Per Jan's review comments, fixed up the driver]
[v9: Allow to continue even if acpi_processor_preregister_perf.. fails]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-03-14 12:35:42 -04:00