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authorAndi Kleen <ak@linux.intel.com>2017-10-13 14:56:42 -0700
committerIngo Molnar <mingo@kernel.org>2017-10-17 17:14:57 +0200
commit0b00de857a648dafe7020878c7a27cf776f5edf4 (patch)
tree0636ebe4115b37999ad5e00ddf41df9f89d188ba /arch/x86/include/asm/cpufeature.h
parentcbe96375025e14fc76f9ed42ee5225120d7210f8 (diff)
x86/cpuid: Add generic table for CPUID dependencies
Some CPUID features depend on other features. Currently it's possible to to clear dependent features, but not clear the base features, which can cause various interesting problems. This patch implements a generic table to describe dependencies between CPUID features, to be used by all code that clears CPUID. Some subsystems (like XSAVE) had an own implementation of this, but it's better to do it all in a single place for everyone. Then clear_cpu_cap and setup_clear_cpu_cap always look up this table and clear all dependencies too. This is intended to be a practical table: only for features that make sense to clear. If someone for example clears FPU, or other features that are essentially part of the required base feature set, not much is going to work. Handling that is right now out of scope. We're only handling features which can be usefully cleared. Signed-off-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Jonathan McDowell <noodles@earth.li> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20171013215645.23166-3-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/cpufeature.h')
-rw-r--r--arch/x86/include/asm/cpufeature.h9
1 files changed, 4 insertions, 5 deletions
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index d59c15c3defd..225fd8374fae 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -125,11 +125,10 @@ extern const char * const x86_bug_flags[NBUGINTS*32];
#define boot_cpu_has(bit) cpu_has(&boot_cpu_data, bit)
#define set_cpu_cap(c, bit) set_bit(bit, (unsigned long *)((c)->x86_capability))
-#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 *)cpu_caps_cleared); \
-} while (0)
+
+extern void setup_clear_cpu_cap(unsigned int bit);
+extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit);
+
#define setup_force_cpu_cap(bit) do { \
set_cpu_cap(&boot_cpu_data, bit); \
set_bit(bit, (unsigned long *)cpu_caps_set); \