linux-kernel - [PATCH] [1/2] Use standard global TLB flushes in MTRR code v2

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Message-Id: <20080208122.996401758@suse.de>
Date:	Fri,  8 Feb 2008 13:22:44 +0100 (CET)
From:	Andi Kleen <ak@...e.de>
To:	mingo@...e.hu, tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: [PATCH] [1/2] Use standard global TLB flushes in MTRR code v2


This is more idiomatic and it does not really make sense for this 
code to implement a own TLB flushing variant.

The control registers will be read/written a few times more, but 
that should not really matter for this code.

v1->v2: Remove unused variable to fix warning

Signed-off-by: Andi Kleen <ak@...e.de>

---
 arch/x86/kernel/cpu/mtrr/generic.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux/arch/x86/kernel/cpu/mtrr/generic.c
===================================================================
--- linux.orig/arch/x86/kernel/cpu/mtrr/generic.c
+++ linux/arch/x86/kernel/cpu/mtrr/generic.c
@@ -324,7 +324,6 @@ static unsigned long set_mtrr_state(void
 }
 
 
-static unsigned long cr4 = 0;
 static DEFINE_SPINLOCK(set_atomicity_lock);
 
 /*
@@ -349,14 +348,8 @@ static void prepare_set(void) __acquires
 	write_cr0(cr0);
 	wbinvd();
 
-	/*  Save value of CR4 and clear Page Global Enable (bit 7)  */
-	if ( cpu_has_pge ) {
-		cr4 = read_cr4();
-		write_cr4(cr4 & ~X86_CR4_PGE);
-	}
-
-	/* Flush all TLBs via a mov %cr3, %reg; mov %reg, %cr3 */
-	__flush_tlb();
+	/* Flush all TLBs */
+	__flush_tlb_all();
 
 	/*  Save MTRR state */
 	rdmsr(MTRRdefType_MSR, deftype_lo, deftype_hi);
@@ -368,7 +361,7 @@ static void prepare_set(void) __acquires
 static void post_set(void) __releases(set_atomicity_lock)
 {
 	/*  Flush TLBs (no need to flush caches - they are disabled)  */
-	__flush_tlb();
+	__flush_tlb_all();
 
 	/* Intel (P6) standard MTRRs */
 	mtrr_wrmsr(MTRRdefType_MSR, deftype_lo, deftype_hi);
@@ -376,9 +369,9 @@ static void post_set(void) __releases(se
 	/*  Enable caches  */
 	write_cr0(read_cr0() & 0xbfffffff);
 
-	/*  Restore value of CR4  */
-	if ( cpu_has_pge )
-		write_cr4(cr4);
+	/* Flush TLBs again to handle prefetches etc. */
+	__flush_tlb_all();
+
 	spin_unlock(&set_atomicity_lock);
 }
 
--
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