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Commit 97cfab6a authored by Andreas Herrmann's avatar Andreas Herrmann Committed by Ingo Molnar
Browse files

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



Starting with commit 8d4a4300 (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: default avatarAndreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ee863ba7

arch/x86/kernel/cpu/addon_cpuid_features.c

+4 −3
Original line number Diff line number Diff line
@@ -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

arch/x86/mm/pat.c

+6 −5
Original line number Diff line number Diff line
@@ -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 */