[PATCH, x86]: Add selfsnoop support

[Uros Bizjak <ubizjak@gmail.com>]

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Hello!

This patch ports the patch that implemented selfsnoop support [1] to 
2.6.28-git. Unfortunately, the thread about the implementation died at 
[2] without any resolution.

The patch works OK on my x86_64, but I don't think this qualifies as a 
thorough test...

This is actually Andi Kleen's patch, his signed-off-by: signature is at [1].

[1] http://lkml.indiana.edu/hypermail/linux/kernel/0802.1/1331.html
[2] http://lkml.indiana.edu/hypermail/linux/kernel/0802.1/1891.html

Uros.



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diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index cfdf8c2..bb6740b 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -229,6 +229,7 @@ extern const char * const x86_power_flags[32];
 #define cpu_has_ds		boot_cpu_has(X86_FEATURE_DS)
 #define cpu_has_pebs		boot_cpu_has(X86_FEATURE_PEBS)
 #define cpu_has_clflush		boot_cpu_has(X86_FEATURE_CLFLSH)
+#define cpu_has_selfsnoop	boot_cpu_has(X86_FEATURE_SELFSNOOP)
 #define cpu_has_bts		boot_cpu_has(X86_FEATURE_BTS)
 #define cpu_has_gbpages		boot_cpu_has(X86_FEATURE_GBPAGES)
 #define cpu_has_arch_perfmon	boot_cpu_has(X86_FEATURE_ARCH_PERFMON)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index e89d248..07d0518 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -150,7 +150,7 @@ static void __cpa_flush_all(void *arg)
 	 */
 	__flush_tlb_all();
 
-	if (cache && boot_cpu_data.x86_model >= 4)
+	if (cache && boot_cpu_data.x86_model >= 4 && cpu_has_selfsnoop)
 		wbinvd();
 }
 
@@ -181,7 +181,7 @@ static void cpa_flush_range(unsigned long start, int numpages, int cache)
 
 	on_each_cpu(__cpa_flush_range, NULL, 1);
 
-	if (!cache)
+	if (!cache || cpu_has_selfsnoop)
 		return;
 
 	/*