---

yaml
---
r: 138759
b: refs/heads/master
c: 3ff42da
h: refs/heads/master
i:
  138757: d999df7
  138755: 9c6851a
  138751: 9aeeda1
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0d890355bff25e1dc03a577a90ed80741489ca54
+refs/heads/master: 3ff42da5048649503e343a32be37b14a6a4e8aaf

trunk/arch/x86/kernel/cpu/mtrr/generic.c

@@ -33,6 +33,32 @@ u64 mtrr_tom2;
 struct mtrr_state_type mtrr_state = {};
 EXPORT_SYMBOL_GPL(mtrr_state);
 
+/**
+ * BIOS is expected to clear MtrrFixDramModEn bit, see for example
+ * "BIOS and Kernel Developer's Guide for the AMD Athlon 64 and AMD
+ * Opteron Processors" (26094 Rev. 3.30 February 2006), section
+ * "13.2.1.2 SYSCFG Register": "The MtrrFixDramModEn bit should be set
+ * to 1 during BIOS initalization of the fixed MTRRs, then cleared to
+ * 0 for operation."
+ */
+static inline void k8_check_syscfg_dram_mod_en(void)
+{
+	u32 lo, hi;
+
+	if (!((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
+	      (boot_cpu_data.x86 >= 0x0f)))
+		return;
+
+	rdmsr(MSR_K8_SYSCFG, lo, hi);
+	if (lo & K8_MTRRFIXRANGE_DRAM_MODIFY) {
+		printk(KERN_ERR FW_WARN "MTRR: CPU %u: SYSCFG[MtrrFixDramModEn]"
+		       " not cleared by BIOS, clearing this bit\n",
+		       smp_processor_id());
+		lo &= ~K8_MTRRFIXRANGE_DRAM_MODIFY;
+		mtrr_wrmsr(MSR_K8_SYSCFG, lo, hi);
+	}
+}
+
 /*
  * Returns the effective MTRR type for the region
  * Error returns:
@@ -166,6 +192,8 @@ get_fixed_ranges(mtrr_type * frs)
 	unsigned int *p = (unsigned int *) frs;
 	int i;
 
+	k8_check_syscfg_dram_mod_en();
+
 	rdmsr(MTRRfix64K_00000_MSR, p[0], p[1]);
 
 	for (i = 0; i < 2; i++)
@@ -305,28 +333,11 @@ void mtrr_wrmsr(unsigned msr, unsigned a, unsigned b)
 			smp_processor_id(), msr, a, b);
 }
 
-/**
- * Enable and allow read/write of extended fixed-range MTRR bits on K8 CPUs
- * see AMD publication no. 24593, chapter 3.2.1 for more information
- */
-static inline void k8_enable_fixed_iorrs(void)
-{
-	unsigned lo, hi;
-
-	rdmsr(MSR_K8_SYSCFG, lo, hi);
-	mtrr_wrmsr(MSR_K8_SYSCFG, lo
-				| K8_MTRRFIXRANGE_DRAM_ENABLE
-				| K8_MTRRFIXRANGE_DRAM_MODIFY, hi);
-}
-
 /**
  * set_fixed_range - checks & updates a fixed-range MTRR if it differs from the value it should have
  * @msr: MSR address of the MTTR which should be checked and updated
  * @changed: pointer which indicates whether the MTRR needed to be changed
  * @msrwords: pointer to the MSR values which the MSR should have
- *
- * If K8 extentions are wanted, update the K8 SYSCFG MSR also.
- * See AMD publication no. 24593, chapter 7.8.1, page 233 for more information.
  */
 static void set_fixed_range(int msr, bool *changed, unsigned int *msrwords)
 {
@@ -335,10 +346,6 @@ static void set_fixed_range(int msr, bool *changed, unsigned int *msrwords)
 	rdmsr(msr, lo, hi);
 
 	if (lo != msrwords[0] || hi != msrwords[1]) {
-		if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
-		    (boot_cpu_data.x86 >= 0x0f && boot_cpu_data.x86 <= 0x11) &&
-		    ((msrwords[0] | msrwords[1]) & K8_MTRR_RDMEM_WRMEM_MASK))
-			k8_enable_fixed_iorrs();
 		mtrr_wrmsr(msr, msrwords[0], msrwords[1]);
 		*changed = true;
 	}
@@ -426,6 +433,8 @@ static int set_fixed_ranges(mtrr_type * frs)
 	bool changed = false;
 	int block=-1, range;
 
+	k8_check_syscfg_dram_mod_en();
+
 	while (fixed_range_blocks[++block].ranges)
 	    for (range=0; range < fixed_range_blocks[block].ranges; range++)
 		set_fixed_range(fixed_range_blocks[block].base_msr + range,