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Commit 9dac6290 authored by Borislav Petkov's avatar Borislav Petkov Committed by Ingo Molnar
Browse files

x86/mm/pat: Untangle pat_init() 



Split it into a BSP and AP version which makes the PAT
initialization path actually readable again.

Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarToshi Kani <toshi.kani@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Elliott@hp.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: hch@lst.de
Cc: hmh@hmh.eng.br
Cc: jgross@suse.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: linux-nvdimm@lists.01.org
Cc: stefan.bader@canonical.com
Cc: yigal@plexistor.com
Link: http://lkml.kernel.org/r/1433436928-31903-2-git-send-email-bp@alien8.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent d6472302

arch/x86/mm/pat.c

+40 −29
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ 
#undef pr_fmt

#define pr_fmt(fmt) "" fmt



static bool boot_cpu_done;



static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT);



static inline void pat_disable(const char *reason)
@@ -194,31 +196,47 @@ void pat_init_cache_modes(void) 


#define PAT(x, y)	((u64)PAT_ ## y << ((x)*8))



void pat_init(void)

static void pat_bsp_init(u64 pat)

{

	u64 pat;

	bool boot_cpu = !boot_pat_state;



	if (!pat_enabled())

	if (!cpu_has_pat) {

		pat_disable("PAT not supported by CPU.");

		return;

	}



	if (!cpu_has_pat) {

	rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);

	if (!boot_pat_state) {

			pat_disable("PAT not supported by CPU.");

		pat_disable("PAT MSR is 0, disabled.");

		return;

		} else {

	}



	wrmsrl(MSR_IA32_CR_PAT, pat);



	pat_init_cache_modes();

}



static void pat_ap_init(u64 pat)

{

	if (!cpu_has_pat) {

		/*

			 * If this happens we are on a secondary CPU, but

			 * switched to PAT on the boot CPU. We have no way to

			 * undo PAT.

		 * If this happens we are on a secondary CPU, but switched to

		 * PAT on the boot CPU. We have no way to undo PAT.

		 */

			pr_err("x86/PAT: PAT enabled, but not supported by secondary CPU\n");

			BUG();

		panic("x86/PAT: PAT enabled, but not supported by secondary CPU\n");

	}



	wrmsrl(MSR_IA32_CR_PAT, pat);

}



	/* Set PWT to Write-Combining. All other bits stay the same */

void pat_init(void)

{

	u64 pat;



	if (!pat_enabled())

		return;



	/*

	 * Set PWT to Write-Combining. All other bits stay the same:

	 *

	 * PTE encoding used in Linux:

	 *      PAT

	 *      |PCD
@@ -233,19 +251,12 @@ void pat_init(void) 
	pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) |

	      PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);



	/* Boot CPU check */

	if (!boot_pat_state) {

		rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);

		if (!boot_pat_state) {

			pat_disable("PAT read returns always zero, disabled.");

			return;

		}

	if (!boot_cpu_done) {

		pat_bsp_init(pat);

		boot_cpu_done = true;

	} else {

		pat_ap_init(pat);

	}



	wrmsrl(MSR_IA32_CR_PAT, pat);



	if (boot_cpu)

		pat_init_cache_modes();

}



#undef PAT