x86: cleanup PAT cpu validation

Move the scattered checks for PAT support to a single function. Its
moved to addon_cpuid_features.c as this file is shared between 32 and
64 bit.

Remove the manipulation of the PAT feature bit and just disable PAT in
the PAT layer, based on the PAT bit provided by the CPU and the
current CPU version/model white list.

Change the boot CPU check so it works on Voyager somewhere in the
future as well :) Also panic, when a secondary has PAT disabled but
the primary one has alrady switched to PAT. We have no way to undo
that.

The white list is kept for now to ensure that we can rely on known to
work CPU types and concentrate on the software induced problems
instead of fighthing CPU erratas and subtle wreckage caused by not yet
verified CPUs. Once the PAT code has stabilized enough, we can remove
the white list and open the can of worms.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 23 insertions, 25 deletions

diff --git a/arch/x86/kernel/cpu/addon_cpuid_features.c b/arch/x86/kernel/cpu/addon_cpuid_features.c
index 238468ae1993..c2e1ce33c7cb 100644
--- a/arch/x86/kernel/cpu/addon_cpuid_features.c
+++ b/arch/x86/kernel/cpu/addon_cpuid_features.c
@@ -6,6 +6,7 @@
 
 #include <linux/cpu.h>
 
+#include <asm/pat.h>
 #include <asm/processor.h>
 
 struct cpuid_bit {
@@ -48,3 +49,23 @@ void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c)
 			set_cpu_cap(c, cb->feature);
 	}
 }
+
+#ifdef CONFIG_X86_PAT
+void __cpuinit validate_pat_support(struct cpuinfo_x86 *c)
+{
+	switch (c->x86_vendor) {
+	case X86_VENDOR_AMD:
+		if (c->x86 >= 0xf && c->x86 <= 0x11)
+			return;
+		break;
+	case X86_VENDOR_INTEL:
+		if (c->x86 == 0xF || (c->x86 == 6 && c->x86_model >= 15))
+			return;
+		break;
+	}
+
+	pat_disable(cpu_has_pat ?
+		    "PAT disabled. Not yet verified on this CPU type." :
+		    "PAT not supported by CPU.");
+}
+#endif
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 35b4f6a9c8ef..d0463a946247 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -12,6 +12,7 @@
 #include <asm/mmu_context.h>
 #include <asm/mtrr.h>
 #include <asm/mce.h>
+#include <asm/pat.h>
 #ifdef CONFIG_X86_LOCAL_APIC
 #include <asm/mpspec.h>
 #include <asm/apic.h>
@@ -308,19 +309,6 @@ static void __cpuinit early_get_cap(struct cpuinfo_x86 *c)
 
 	}
 
-	clear_cpu_cap(c, X86_FEATURE_PAT);
-
-	switch (c->x86_vendor) {
-	case X86_VENDOR_AMD:
-		if (c->x86 >= 0xf && c->x86 <= 0x11)
-			set_cpu_cap(c, X86_FEATURE_PAT);
-		break;
-	case X86_VENDOR_INTEL:
-		if (c->x86 == 0xF || (c->x86 == 6 && c->x86_model >= 15))
-			set_cpu_cap(c, X86_FEATURE_PAT);
-		break;
-	}
-
 }
 
 /*
@@ -409,18 +397,6 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
 		init_scattered_cpuid_features(c);
 	}
 
-	clear_cpu_cap(c, X86_FEATURE_PAT);
-
-	switch (c->x86_vendor) {
-	case X86_VENDOR_AMD:
-		if (c->x86 >= 0xf && c->x86 <= 0x11)
-			set_cpu_cap(c, X86_FEATURE_PAT);
-		break;
-	case X86_VENDOR_INTEL:
-		if (c->x86 == 0xF || (c->x86 == 6 && c->x86_model >= 15))
-			set_cpu_cap(c, X86_FEATURE_PAT);
-		break;
-	}
 }
 
 static void __cpuinit squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
@@ -651,6 +627,7 @@ void __init early_cpu_init(void)
 		cpu_devs[cvdev->vendor] = cvdev->cpu_dev;
 
 	early_cpu_detect();
+	validate_pat_support(&boot_cpu_data);
 }
 
 /* Make sure %fs is initialized properly in idle threads */