Commit 88b094fb authored by Alok Kataria's avatar Alok Kataria Committed by H. Peter Anvin
Browse files

x86: Hypervisor detection and get tsc_freq from hypervisor 



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: default avatarAlok N Kataria <akataria@vmware.com>
Signed-off-by: default avatarDan Hecht <dhecht@vmware.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 49ab56ac

arch/x86/include/asm/hypervisor.h

0 → 100644
+26 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2008, VMware, Inc.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or

 * NON INFRINGEMENT.  See the GNU General Public License for more

 * details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

#ifndef ASM_X86__HYPERVISOR_H

#define ASM_X86__HYPERVISOR_H



extern unsigned long get_hypervisor_tsc_freq(void);

extern void init_hypervisor(struct cpuinfo_x86 *c);



#endif

arch/x86/include/asm/processor.h

+4 −0
Original line number Diff line number Diff line
@@ -110,6 +110,7 @@ struct cpuinfo_x86 { 
	/* Index into per_cpu list: */

	u16			cpu_index;

#endif

	unsigned int		x86_hyper_vendor;

} __attribute__((__aligned__(SMP_CACHE_BYTES)));



#define X86_VENDOR_INTEL	0
@@ -123,6 +124,9 @@ struct cpuinfo_x86 { 


#define X86_VENDOR_UNKNOWN	0xff



#define X86_HYPER_VENDOR_NONE  0

#define X86_HYPER_VENDOR_VMWARE 1



/*

 * capabilities of CPUs

 */

arch/x86/include/asm/vmware.h

0 → 100644
+26 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2008, VMware, Inc.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or

 * NON INFRINGEMENT.  See the GNU General Public License for more

 * details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

#ifndef ASM_X86__VMWARE_H

#define ASM_X86__VMWARE_H



extern unsigned long vmware_get_tsc_khz(void);

extern int vmware_platform(void);



#endif

arch/x86/kernel/cpu/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 


obj-y			:= intel_cacheinfo.o addon_cpuid_features.o

obj-y			+= proc.o capflags.o powerflags.o common.o

obj-y			+= vmware.o hypervisor.o



obj-$(CONFIG_X86_32)	+= bugs.o cmpxchg.o

obj-$(CONFIG_X86_64)	+= bugs_64.o

arch/x86/kernel/cpu/common.c

+2 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <asm/proto.h>

#include <asm/sections.h>

#include <asm/setup.h>

#include <asm/hypervisor.h>



#include "cpu.h"
@@ -703,6 +704,7 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c) 
	detect_ht(c);

#endif



	init_hypervisor(c);

	/*

	 * On SMP, boot_cpu_data holds the common feature set between

	 * all CPUs; so make sure that we indicate which features are

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