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Commit 2d9ce177 authored by Avi Kivity's avatar Avi Kivity Committed by Linus Torvalds
Browse files

i386: Allow KVM on i386 nonpae 



Currently, CONFIG_X86_CMPXCHG64 both enables boot-time checking of
the cmpxchg64b feature and enables compilation of the set_64bit() family.
Since the option is dependent on PAE, and since KVM depends on set_64bit(),
this effectively disables KVM on i386 nopae.

Simplify by removing the config option altogether: the boot check is made
dependent on CONFIG_X86_PAE directly, and the set_64bit() family is exposed
without constraints.  It is up to users to check for the feature flag (KVM
does not as virtualiation extensions imply its existence).

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3e1f900b

arch/i386/Kconfig.cpu

+0 −5
Original line number Diff line number Diff line
@@ -297,11 +297,6 @@ config X86_POPAD_OK 
	depends on !M386

	default y



config X86_CMPXCHG64

	bool

	depends on X86_PAE

	default y



config X86_ALIGNMENT_16

	bool

	depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1

arch/i386/defconfig

+0 −1
Original line number Diff line number Diff line
@@ -166,7 +166,6 @@ CONFIG_X86_WP_WORKS_OK=y 
CONFIG_X86_INVLPG=y

CONFIG_X86_BSWAP=y

CONFIG_X86_POPAD_OK=y

CONFIG_X86_CMPXCHG64=y

CONFIG_X86_GOOD_APIC=y

CONFIG_X86_INTEL_USERCOPY=y

CONFIG_X86_USE_PPRO_CHECKSUM=y

arch/um/defconfig

+0 −1
Original line number Diff line number Diff line
@@ -52,7 +52,6 @@ CONFIG_X86_WP_WORKS_OK=y 
CONFIG_X86_INVLPG=y

CONFIG_X86_BSWAP=y

CONFIG_X86_POPAD_OK=y

CONFIG_X86_CMPXCHG64=y

CONFIG_X86_GOOD_APIC=y

CONFIG_X86_USE_PPRO_CHECKSUM=y

CONFIG_X86_TSC=y

drivers/kvm/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -11,7 +11,6 @@ if VIRTUALIZATION 
config KVM

	tristate "Kernel-based Virtual Machine (KVM) support"

	depends on X86 && EXPERIMENTAL

	depends on X86_CMPXCHG64 || 64BIT

	---help---

	  Support hosting fully virtualized guest machines using hardware

	  virtualization extensions.  You will need a fairly recent

include/asm-i386/cmpxchg.h

+5 −9
Original line number Diff line number Diff line
@@ -3,14 +3,16 @@ 


#include <linux/bitops.h> /* for LOCK_PREFIX */



/*

 * Note: if you use set64_bit(), __cmpxchg64(), or their variants, you

 *       you need to test for the feature in boot_cpu_data.

 */



#define xchg(ptr,v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v),(ptr),sizeof(*(ptr))))



struct __xchg_dummy { unsigned long a[100]; };

#define __xg(x) ((struct __xchg_dummy *)(x))





#ifdef CONFIG_X86_CMPXCHG64



/*

 * The semantics of XCHGCMP8B are a bit strange, this is why

 * there is a loop and the loading of %%eax and %%edx has to
@@ -65,8 +67,6 @@ static inline void __set_64bit_var (unsigned long long *ptr, 
 __set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \

 __set_64bit(ptr, ll_low(value), ll_high(value)) )



#endif



/*

 * Note: no "lock" prefix even on SMP: xchg always implies lock anyway

 * Note 2: xchg has side effect, so that attribute volatile is necessary,
@@ -252,8 +252,6 @@ static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old, 
})

#endif



#ifdef CONFIG_X86_CMPXCHG64



static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old,

				      unsigned long long new)

{
@@ -289,5 +287,3 @@ static inline unsigned long long __cmpxchg64_local(volatile void *ptr, 
	((__typeof__(*(ptr)))__cmpxchg64_local((ptr),(unsigned long long)(o),\

					(unsigned long long)(n)))

#endif
 


#endif