x86: PAT: fix ambiguous paranoia check in pat_init()

Starting with commit 8d4a4300854f3971502e81dacd930704cb88f606 (x86:
cleanup PAT cpu validation) the PAT CPU feature flag is not cleared
anymore. Now the error message

  "PAT enabled, but CPU feature cleared"

in pat_init() is misleading.

Furthermore the current code does not check for existence of the PAT
CPU feature flag if a CPU is whitelisted in validate_pat_support.

This patch clears pat_wc_enabled if boot CPU has no PAT feature flag
and adapts the paranoia check.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/cpu/addon_cpuid_features.c b/arch/x86/kernel/cpu/addon_cpuid_features.c
index 0fbd06241e074348d4cfddf5e898683cd2a40926..2df461f06a525e4a125513c823fb7cf49d5c3964 100644 (file)
--- a/arch/x86/kernel/cpu/addon_cpuid_features.c
+++ b/arch/x86/kernel/cpu/addon_cpuid_features.c
@@ -53,6 +53,9 @@ void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_PAT
 void __cpuinit validate_pat_support(struct cpuinfo_x86 *c)
 {
+       if (!cpu_has_pat)
+               pat_disable("PAT not supported by CPU.");
+
        switch (c->x86_vendor) {
        case X86_VENDOR_INTEL:
                if (c->x86 == 0xF || (c->x86 == 6 && c->x86_model >= 15))
@@ -64,8 +67,6 @@ void __cpuinit validate_pat_support(struct cpuinfo_x86 *c)
                return;
        }
 
-       pat_disable(cpu_has_pat ?
-                   "PAT disabled. Not yet verified on this CPU type." :
-                   "PAT not supported by CPU.");
+       pat_disable("PAT disabled. Not yet verified on this CPU type.");
 }
 #endif

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 320d644a8107fa56e829248cb3be84b7167985bf..65105b1195a391a8b69c9131509e13dd7e07eba6 100644 (file)
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -76,14 +76,15 @@ void pat_init(void)
                return;
 
        /* Paranoia check. */
-       if (!cpu_has_pat) {
-               printk(KERN_ERR "PAT enabled, but CPU feature cleared\n");
+       if (!cpu_has_pat && boot_pat_state) {
                /*
-                * Panic if this happens on the secondary CPU, and we
+                * If this happens we are on a secondary CPU, but
                 * switched to PAT on the boot CPU. We have no way to
                 * undo PAT.
-               */
-               BUG_ON(boot_pat_state);
+                */
+               printk(KERN_ERR "PAT enabled, "
+                      "but not supported by secondary CPU\n");
+               BUG();
        }
 
        /* Set PWT to Write-Combining. All other bits stay the same */