[Xen-changelog] [xen-unstable] x86, amd, MTRR: remove k8_enable_fixed_iorrs()

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Wei Huang <wei.huang2@xxxxxxx>
# Date 1302076933 -3600
# Node ID 42fa70e0761bbb0596618ca5323664f31a2faa76
# Parent  8fb61c9ebe499b576687907d164da07802414925
x86, amd, MTRR: remove k8_enable_fixed_iorrs()

AMD64 defines two special bits (bit 3 and 4) RdMem and WrMem in fixed
MTRR type. Their values are supposed to be 0 after BIOS hands the
control to OS according to AMD BKDG. Unless OS specificially turn them
on, they are kept 0 all the time. As a result, k8_enable_fixed_iorrs()
is unnecessary and removed from upstream kernel (see
https://patchwork.kernel.org/patch/11425/). This patch does the same
thing.

Signed-off-by: Wei Huang <wei.huang2@xxxxxxx>
---


diff -r 8fb61c9ebe49 -r 42fa70e0761b xen/arch/x86/cpu/mtrr/generic.c
--- a/xen/arch/x86/cpu/mtrr/generic.c   Wed Apr 06 09:01:31 2011 +0100
+++ b/xen/arch/x86/cpu/mtrr/generic.c   Wed Apr 06 09:02:13 2011 +0100
@@ -116,20 +116,6 @@
 }
 
 /**
- * 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)
-{
-       uint64_t msr_content;
-
-       rdmsrl(MSR_K8_SYSCFG, msr_content);
-       mtrr_wrmsr(MSR_K8_SYSCFG, msr_content 
-                               | K8_MTRRFIXRANGE_DRAM_ENABLE
-                               | K8_MTRRFIXRANGE_DRAM_MODIFY);
-}
-
-/**
  * Checks and updates an fixed-range MTRR if it differs from the value it
  * should have. If K8 extenstions are wanted, update the K8 SYSCFG MSR also.
  * see AMD publication no. 24593, chapter 7.8.1, page 233 for more information
@@ -145,10 +131,6 @@
        val = ((uint64_t)msrwords[1] << 32) | msrwords[0];
 
        if (msr_content != val) {
-               if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
-                   boot_cpu_data.x86 == 15 &&
-                   ((msrwords[0] | msrwords[1]) & K8_MTRR_RDMEM_WRMEM_MASK))
-                       k8_enable_fixed_iorrs();
                mtrr_wrmsr(msr, val);
                *changed = TRUE;
        }

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