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path: root/arch/x86/kernel/cpu/hypervisor.c
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2018-01-14x86/jailhouse: Add infrastructure for running in non-root cellJan Kiszka
The Jailhouse hypervisor is able to statically partition a multicore system into multiple so-called cells. Linux is used as boot loader and continues to run in the root cell after Jailhouse is enabled. Linux can also run in non-root cells. Jailhouse does not emulate usual x86 devices. It also provides no complex ACPI but basic platform information that the boot loader forwards via setup data. This adds the infrastructure to detect when running in a non-root cell so that the platform can be configured as required in succeeding steps. Support is limited to x86-64 so far, primarily because no boot loader stub exists for i386 and, thus, we wouldn't be able to test the 32-bit path. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: jailhouse-dev@googlegroups.com Link: https://lkml.kernel.org/r/7f823d077b38b1a70c526b40b403f85688c137d3.1511770314.git.jan.kiszka@siemens.com
2017-11-10x86/virt: Add enum for hypervisors to replace x86_hyperJuergen Gross
The x86_hyper pointer is only used for checking whether a virtual device is supporting the hypervisor the system is running on. Use an enum for that purpose instead and drop the x86_hyper pointer. Signed-off-by: Juergen Gross <jgross@suse.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Xavier Deguillard <xdeguillard@vmware.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: akataria@vmware.com Cc: arnd@arndb.de Cc: boris.ostrovsky@oracle.com Cc: devel@linuxdriverproject.org Cc: dmitry.torokhov@gmail.com Cc: gregkh@linuxfoundation.org Cc: haiyangz@microsoft.com Cc: kvm@vger.kernel.org Cc: kys@microsoft.com Cc: linux-graphics-maintainer@vmware.com Cc: linux-input@vger.kernel.org Cc: moltmann@vmware.com Cc: pbonzini@redhat.com Cc: pv-drivers@vmware.com Cc: rkrcmar@redhat.com Cc: sthemmin@microsoft.com Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/20171109132739.23465-3-jgross@suse.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-10x86/virt, x86/platform: Merge 'struct x86_hyper' into 'struct x86_platform' ↵Juergen Gross
and 'struct x86_init' Instead of x86_hyper being either NULL on bare metal or a pointer to a struct hypervisor_x86 in case of the kernel running as a guest merge the struct into x86_platform and x86_init. This will remove the need for wrappers making it hard to find out what is being called. With dummy functions added for all callbacks testing for a NULL function pointer can be removed, too. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Juergen Gross <jgross@suse.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: akataria@vmware.com Cc: boris.ostrovsky@oracle.com Cc: devel@linuxdriverproject.org Cc: haiyangz@microsoft.com Cc: kvm@vger.kernel.org Cc: kys@microsoft.com Cc: pbonzini@redhat.com Cc: rkrcmar@redhat.com Cc: rusty@rustcorp.com.au Cc: sthemmin@microsoft.com Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/20171109132739.23465-2-jgross@suse.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-02x86/cpu: remove hypervisor specific set_cpu_featuresJuergen Gross
There is no user of x86_hyper->set_cpu_features() any more. Remove it. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2017-05-02x86/xen: add CONFIG_XEN_PV to KconfigVitaly Kuznetsov
All code to support Xen PV will get under this new option. For the beginning, check for it in the common code. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2017-05-02x86/xen: separate PV and HVM hypervisorsVitaly Kuznetsov
As a preparation to splitting the code we need to untangle it: x86_hyper_xen -> x86_hyper_xen_hvm and x86_hyper_xen_pv xen_platform() -> xen_platform_hvm() and xen_platform_pv() xen_cpu_up_prepare() -> xen_cpu_up_prepare_pv() and xen_cpu_up_prepare_hvm() xen_cpu_dead() -> xen_cpu_dead_pv() and xen_cpu_dead_pv_hvm() Add two parameters to xen_cpuhp_setup() to pass proper cpu_up_prepare and cpu_dead hooks. xen_set_cpu_features() is now PV-only so the redundant xen_pv_domain() check can be dropped. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2016-09-05virt, sched: Add generic vCPU pinning supportJuergen Gross
Add generic virtualization support for pinning the current vCPU to a specified physical CPU. As this operation isn't performance critical (a very limited set of operations like BIOS calls and SMIs is expected to need this) just add a hypervisor specific indirection. Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Douglas_Warzecha@dell.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akataria@vmware.com Cc: boris.ostrovsky@oracle.com Cc: chrisw@sous-sol.org Cc: david.vrabel@citrix.com Cc: hpa@zytor.com Cc: jdelvare@suse.com Cc: jeremy@goop.org Cc: linux@roeck-us.net Cc: pali.rohar@gmail.com Cc: rusty@rustcorp.com.au Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1472453327-19050-3-git-send-email-jgross@suse.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14x86/kernel: Audit and remove any unnecessary uses of module.hPaul Gortmaker
Historically a lot of these existed because we did not have a distinction between what was modular code and what was providing support to modules via EXPORT_SYMBOL and friends. That changed when we forked out support for the latter into the export.h file. This means we should be able to reduce the usage of module.h in code that is obj-y Makefile or bool Kconfig. The advantage in doing so is that module.h itself sources about 15 other headers; adding significantly to what we feed cpp, and it can obscure what headers we are effectively using. Since module.h was the source for init.h (for __init) and for export.h (for EXPORT_SYMBOL) we consider each obj-y/bool instance for the presence of either and replace as needed. Build testing revealed some implicit header usage that was fixed up accordingly. Note that some bool/obj-y instances remain since module.h is the header for some exception table entry stuff, and for things like __init_or_module (code that is tossed when MODULES=n). Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160714001901.31603-4-paul.gortmaker@windriver.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-03x86/cpu: Convert printk(KERN_<LEVEL> ...) to pr_<level>(...)Chen Yucong
- Use the more current logging style pr_<level>(...) instead of the old printk(KERN_<LEVEL> ...). - Convert pr_warning() to pr_warn(). Signed-off-by: Chen Yucong <slaoub@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1454384702-21707-1-git-send-email-slaoub@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-05hypervisor/x86/xen: Unset X86_BUG_SYSRET_SS_ATTRS on Xen PV guestsBoris Ostrovsky
Commit 61f01dd941ba ("x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue") makes AMD processors set SS to __KERNEL_DS in __switch_to() to deal with cases when SS is NULL. This breaks Xen PV guests who do not want to load SS with__KERNEL_DS. Since the problem that the commit is trying to address would have to be fixed in the hypervisor (if it in fact exists under Xen) there is no reason to set X86_BUG_SYSRET_SS_ATTRS flag for PV VPCUs here. This can be easily achieved by adding x86_hyper_xen_hvm.set_cpu_features op which will clear this flag. (And since this structure is no longer HVM-specific we should do some renaming). Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
2013-08-05x86: Correctly detect hypervisorJason Wang
We try to handle the hypervisor compatibility mode by detecting hypervisor through a specific order. This is not robust, since hypervisors may implement each others features. This patch tries to handle this situation by always choosing the last one in the CPUID leaves. This is done by letting .detect() return a priority instead of true/false and just re-using the CPUID leaf where the signature were found as the priority (or 1 if it was found by DMI). Then we can just pick hypervisor who has the highest priority. Other sophisticated detection method could also be implemented on top. Suggested by H. Peter Anvin and Paolo Bonzini. Acked-by: K. Y. Srinivasan <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Doug Covelli <dcovelli@vmware.com> Cc: Borislav Petkov <bp@suse.de> Cc: Dan Hecht <dhecht@vmware.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Link: http://lkml.kernel.org/r/1374742475-2485-4-git-send-email-jasowang@redhat.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-07-14x86: delete __cpuinit usage from all x86 filesPaul Gortmaker
The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. Note that some harmless section mismatch warnings may result, since notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c) are flagged as __cpuinit -- so if we remove the __cpuinit from arch specific callers, we will also get section mismatch warnings. As an intermediate step, we intend to turn the linux/init.h cpuinit content into no-ops as early as possible, since that will get rid of these warnings. In any case, they are temporary and harmless. This removes all the arch/x86 uses of the __cpuinit macros from all C files. x86 only had the one __CPUINIT used in assembly files, and it wasn't paired off with a .previous or a __FINIT, so we can delete it directly w/o any corresponding additional change there. [1] https://lkml.org/lkml/2013/5/20/589 Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Acked-by: Ingo Molnar <mingo@kernel.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-01-24x86/apic: Allow x2apic without IR on VMware platformAlok N Kataria
This patch updates x2apic initializaition code to allow x2apic on VMware platform even without interrupt remapping support. The hypervisor_x2apic_available hook was added in x2apic initialization code and used by KVM and XEN, before this. I have also cleaned up that code to export this hook through the hypervisor_x86 structure. Compile tested for KVM and XEN configs, this patch doesn't have any functional effect on those two platforms. On VMware platform, verified that x2apic is used in physical mode on products that support this. Signed-off-by: Alok N Kataria <akataria@vmware.com> Reviewed-by: Doug Covelli <dcovelli@vmware.com> Reviewed-by: Dan Hecht <dhecht@vmware.com> Acked-by: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Avi Kivity <avi@redhat.com> Link: http://lkml.kernel.org/r/1358466282.423.60.camel@akataria-dtop.eng.vmware.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-07-18x86, hyper: fix build with !CONFIG_KVM_GUESTAvi Kivity
Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2012-07-11KVM: Add x86_hyper_kvm to complete detect_hypervisor_platform checkPrarit Bhargava
While debugging I noticed that unlike all the other hypervisor code in the kernel, kvm does not have an entry for x86_hyper which is used in detect_hypervisor_platform() which results in a nice printk in the syslog. This is only really a stub function but it does make kvm more consistent with the other hypervisors. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: Avi Kivity <avi@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Marcelo Tostatti <mtosatti@redhat.com> Cc: kvm@vger.kernel.org Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-08x86, hyper: Change hypervisor detection orderAnupam Chanda
Detect Xen before HyperV because in Viridian compatibility mode Xen presents itself as HyperV. Move Xen to the top since it seems more likely that Xen would emulate VMware than vice versa. Signed-off-by: Anupam Chanda <achanda@nicira.com> Link: http://lkml.kernel.org/r/1310150570-26810-1-git-send-email-achanda@nicira.com Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Acked-by: Yaozu (Eddie) Dong <eddie.dong@intel.com> Reviewed-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-07-29Introduce CONFIG_XEN_PVHVM compile optionStefano Stabellini
This patch introduce a CONFIG_XEN_PVHVM compile time option to enable/disable Xen PV on HVM support. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
2010-07-26xen/pvhvm: fix build problem when !CONFIG_XENJeremy Fitzhardinge
x86_hyper_xen_hvm is only defined when Xen is enabled in the kernel config. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
2010-07-22x86: early PV on HVM features initialization.Sheng Yang
Initialize basic pv on hvm features adding a new Xen HVM specific hypervisor_x86 structure. Don't try to initialize xen-kbdfront and xen-fbfront when running on HVM because the backends are not available. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
2010-05-09x86, hypervisor: add missing <linux/module.h>H. Peter Anvin
EXPORT_SYMBOL() needs <linux/module.h> to be included; fixes modular builds of the VMware balloon driver, and any future modular drivers which depends on the hypervisor. Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Greg KH <greg@kroah.com> Cc: Hank Janssen <hjanssen@microsoft.com> Cc: Alok Kataria <akataria@vmware.com> Cc: Ky Srinivasan <ksrinivasan@novell.com> Cc: Dmitry Torokhov <dtor@vmware.com> LKML-Reference: <4BE49778.6060800@zytor.com>
2010-05-09x86, hypervisor: Export the x86_hyper* symbolsH. Peter Anvin
Export x86_hyper and the related specific structures, allowing for hypervisor identification by modules. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Greg KH <greg@kroah.com> Cc: Hank Janssen <hjanssen@microsoft.com> Cc: Alok Kataria <akataria@vmware.com> Cc: Ky Srinivasan <ksrinivasan@novell.com> Cc: Dmitry Torokhov <dtor@vmware.com> LKML-Reference: <4BE49778.6060800@zytor.com>
2010-05-07x86: Clean up the hypervisor layerH. Peter Anvin
Clean up the hypervisor layer and the hypervisor drivers, using an ops structure instead of an enumeration with if statements. The identity of the hypervisor, if needed, can be tested by testing the pointer value in x86_hyper. The MS-HyperV private state is moved into a normal global variable (it's per-system state, not per-CPU state). Being a normal bss variable, it will be left at all zero on non-HyperV platforms, and so can generally be tested for HyperV-specific features without additional qualification. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Acked-by: Greg KH <greg@kroah.com> Cc: Hank Janssen <hjanssen@microsoft.com> Cc: Alok Kataria <akataria@vmware.com> Cc: Ky Srinivasan <ksrinivasan@novell.com> LKML-Reference: <4BE49778.6060800@zytor.com>
2010-05-06x86: Detect running on a Microsoft HyperV systemKy Srinivasan
This patch integrates HyperV detection within the framework currently used by VmWare. With this patch, we can avoid having to replicate the HyperV detection code in each of the Microsoft HyperV drivers. Reworked and tweaked by Greg K-H to build properly. Signed-off-by: K. Y. Srinivasan <ksrinivasan@novell.com> LKML-Reference: <20100506190841.GA1605@kroah.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Vadim Rozenfeld <vrozenfe@redhat.com> Cc: Avi Kivity <avi@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "K.Prasad" <prasad@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Stephane Eranian <eranian@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Alan Cox <alan@linux.intel.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Hank Janssen <hjanssen@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-08-31x86: Move tsc_calibration to x86_init_opsThomas Gleixner
TSC calibration is modified by the vmware hypervisor and paravirt by separate means. Moorestown wants to add its own calibration routine as well. So make calibrate_tsc a proper x86_init_ops function and override it by paravirt or by the early setup of the vmware hypervisor. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-07-11x86/cpu: Clean up various files a bitAlan Cox
No code changes except printk levels (although some of the K6 mtrr code might be clearer if there were a few as would splitting out some of the intel cache code). Signed-off-by: Alan Cox <alan@linux.intel.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-23x86: hypervisor - fix sparse warningsHannes Eder
Impact: fix sparse build warning Fix the following sparse warnings: arch/x86/kernel/cpu/hypervisor.c:37:15: warning: symbol 'get_hypervisor_tsc_freq' was not declared. Should it be static? arch/x86/kernel/cpu/hypervisor.c:53:16: warning: symbol 'init_hypervisor' was not declared. Should it be static? Signed-off-by: Hannes Eder <hannes@hanneseder.net> Cc: "Alok N Kataria" <akataria@vmware.com> Cc: "Dan Hecht" <dhecht@vmware.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-01x86: Add a synthetic TSC_RELIABLE feature bit.Alok Kataria
Impact: Changes timebase calibration on Vmware. Use the synthetic TSC_RELIABLE bit to workaround virtualization anomalies. Virtual TSCs can be kept nearly in sync, but because the virtual TSC offset is set by software, it's not perfect. So, the TSC synchronization test can fail. Even then the TSC can be used as a clocksource since the VMware platform exports a reliable TSC to the guest for timekeeping purposes. Use this bit to check if we need to skip the TSC sync checks. Along with this also set the CONSTANT_TSC bit when on VMware, since we still want to use TSC as clocksource on VM running over hardware which has unsynchronized TSC's (opteron's), since the hypervisor will take care of providing consistent TSC to the guest. Signed-off-by: Alok N Kataria <akataria@vmware.com> Signed-off-by: Dan Hecht <dhecht@vmware.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-11-01x86: Hypervisor detection and get tsc_freq from hypervisorAlok Kataria
Impact: Changes timebase calibration on Vmware. v3->v2 : Abstract the hypervisor detection and feature (tsc_freq) request behind a hypervisor.c file v2->v1 : Add a x86_hyper_vendor field to the cpuinfo_x86 structure. This avoids multiple calls to the hypervisor detection function. This patch adds function to detect if we are running under VMware. The current way to check if we are on VMware is following, # check if "hypervisor present bit" is set, if so read the 0x40000000 cpuid leaf and check for "VMwareVMware" signature. # if the above fails, check the DMI vendors name for "VMware" string if we find one we query the VMware hypervisor port to check if we are under VMware. The DMI + "VMware hypervisor port check" is needed for older VMware products, which don't implement the hypervisor signature cpuid leaf. Also note that since we are checking for the DMI signature the hypervisor port should never be accessed on native hardware. This patch also adds a hypervisor_get_tsc_freq function, instead of calibrating the frequency which can be error prone in virtualized environment, we ask the hypervisor for it. We get the frequency from the hypervisor by accessing the hypervisor port if we are running on VMware. Other hypervisors too can add code to the generic routine to get frequency on their platform. Signed-off-by: Alok N Kataria <akataria@vmware.com> Signed-off-by: Dan Hecht <dhecht@vmware.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>