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: Avi Kivity <avi@qumranet.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/i386/Kconfig.cpu b/arch/i386/Kconfig.cpu
index 9cbe76c3aa359763c6650aa4a57d97c16ee5d4e4..11a24d54f27bb667696c8acf790b9e25f9dd8613 100644 (file)
--- a/arch/i386/Kconfig.cpu
+++ b/arch/i386/Kconfig.cpu
@@ -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

diff --git a/arch/i386/defconfig b/arch/i386/defconfig
index 1a3a2217b7c27c6c1cd2ee6382147c8a61e70e76..0ac62cdcd3b7843f18839cd81b7fe8852565f41c 100644 (file)
--- a/arch/i386/defconfig
+++ b/arch/i386/defconfig
@@ -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

diff --git a/arch/um/defconfig b/arch/um/defconfig
index a25cd25d55d44d67335527a947655ec89037e460..1e0f677c2f4685e8eabd652c9ff3d60f76dbf28e 100644 (file)
--- a/arch/um/defconfig
+++ b/arch/um/defconfig
@@ -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

diff --git a/drivers/kvm/Kconfig b/drivers/kvm/Kconfig
index 33fa28a8c1993d5dd3cc258ec3896e41b0941cbb..2f661e5f0dae67f37209879e34bbf50546d4486b 100644 (file)
--- a/drivers/kvm/Kconfig
+++ b/drivers/kvm/Kconfig
@@ -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

diff --git a/include/asm-i386/cmpxchg.h b/include/asm-i386/cmpxchg.h
index 7adcef0cd53b88dae0a1dc478606b31bc4b0d401..64dcdf46117bf2c1dbaeba8e88fa36912fab67c2 100644 (file)
--- a/include/asm-i386/cmpxchg.h
+++ b/include/asm-i386/cmpxchg.h
@@ -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

diff --git a/include/asm-i386/required-features.h b/include/asm-i386/required-features.h
index 65848a007050911e3207b1d2e682ba4499c25ec9..618feb98f9f5de4f67eaeebae2ebab62ff967946 100644 (file)
--- a/include/asm-i386/required-features.h
+++ b/include/asm-i386/required-features.h
@@ -29,7 +29,7 @@
 # define NEED_CMOV     0
 #endif
 
-#ifdef CONFIG_X86_CMPXCHG64
+#ifdef CONFIG_X86_PAE
 # define NEED_CX8      (1<<(X86_FEATURE_CX8 & 31))
 #else
 # define NEED_CX8      0