[tip:x86/cpufeature] x86: clean up and fix setup_clear/force_cpu_cap handling

tip-bot for Yinghai Lu
2009-05-11T09:56:27Z

Commit-ID: 3e0c373749d7eb5b354ac0b043f2b2cdf84eefef
Gitweb: http://git.kernel.org/tip/3e0c373749d7eb5b354ac0b043f2b2cdf84eefef
Author: Yinghai Lu <yinghai@kernel.org>
AuthorDate: Sat, 9 May 2009 23:47:42 -0700
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 11 May 2009 10:57:24 +0200

x86: clean up and fix setup_clear/force_cpu_cap handling

setup_force_cpu_cap() only have one user (Xen guest code),
but it should not reuse cleared_cpu_cpus, otherwise it
will have problems on SMP.

Need to have a separate cpu_cpus_set array too, for forced-on
flags, beyond the forced-off flags.

Also need to setup handling before all cpus caps are combined.

[ Impact: fix the forced-set CPU feature flag logic ]

Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Yinghai Lu <yinghai.lu@kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
arch/x86/include/asm/cpufeature.h | 4 ++--
arch/x86/include/asm/processor.h | 3 ++-
arch/x86/kernel/cpu/common.c | 17 ++++++++++++-----
3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index ccc1061..13cc6a5 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -192,11 +192,11 @@ extern const char * const x86_power_flags[32];
#define clear_cpu_cap(c, bit) clear_bit(bit, (unsigned long *)((c)->x86_capability))
#define setup_clear_cpu_cap(bit) do { \
clear_cpu_cap(&boot_cpu_data, bit); \
- set_bit(bit, (unsigned long *)cleared_cpu_caps); \
+ set_bit(bit, (unsigned long *)cpu_caps_cleared); \
} while (0)
#define setup_force_cpu_cap(bit) do { \
set_cpu_cap(&boot_cpu_data, bit); \
- clear_bit(bit, (unsigned long *)cleared_cpu_caps); \
+ set_bit(bit, (unsigned long *)cpu_caps_set); \
} while (0)

#define cpu_has_fpu boot_cpu_has(X86_FEATURE_FPU)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c2cceae..fed93fe 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -135,7 +135,8 @@ extern struct cpuinfo_x86 boot_cpu_data;
extern struct cpuinfo_x86 new_cpu_data;

extern struct tss_struct doublefault_tss;
-extern __u32 cleared_cpu_caps[NCAPINTS];
+extern __u32 cpu_caps_cleared[NCAPINTS];
+extern __u32 cpu_caps_set[NCAPINTS];

#ifdef CONFIG_SMP
DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c4f6678..e7fd5c4 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -292,7 +292,8 @@ static const char *__cpuinit table_lookup_model(struct cpuinfo_x86 *c)
return NULL; /* Not found */
}

-__u32 cleared_cpu_caps[NCAPINTS] __cpuinitdata;
+__u32 cpu_caps_cleared[NCAPINTS] __cpuinitdata;
+__u32 cpu_caps_set[NCAPINTS] __cpuinitdata;

void load_percpu_segment(int cpu)
{
@@ -806,6 +807,16 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
#endif

init_hypervisor(c);
+
+ /*
+ * Clear/Set all flags overriden by options, need do it
+ * before following smp all cpus cap AND.
+ */
+ for (i = 0; i < NCAPINTS; i++) {
+ c->x86_capability[i] &= ~cpu_caps_cleared[i];
+ c->x86_capability[i] |= cpu_caps_set[i];
+ }
+
/*
* On SMP, boot_cpu_data holds the common feature set between
* all CPUs; so make sure that we indicate which features are
@@ -818,10 +829,6 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
boot_cpu_data.x86_capability[i] &= c->x86_capability[i];
}

- /* Clear all flags overriden by options */
- for (i = 0; i < NCAPINTS; i++)
- c->x86_capability[i] &= ~cleared_cpu_caps[i];
-
#ifdef CONFIG_X86_MCE
/* Init Machine Check Exception if available. */
mcheck_init(c);