In some virtualization systems like KVM where MTRR registers
are not accessible output looks like :

MTRR registers:
MTRRcap (0xfe): MTRRphysBase0 (0x200): MTRRphysMask0 (0x201): MTRRphysBase1 
(0x202): MTRRphysMask1 (0x203): MTRRphysBase2 (0x204): MTRRphysMask2 (0x205): 
MTRRphysBase3 (0x206): MTRRphysMask3 (0x207): MTRRphysBase4 (0x208): 
MTRRphysMask4 (0x209): MTRRphysBase5 (0x20a): MTRRphysMask5 (0x20b): 
MTRRphysBase6 (0x20c): MTRRphysMask6 (0x20d): MTRRphysBase7 (0x20e): 
MTRRphysMask7 (0x20f): MTRRfix64K_00000 (0x250): MTRRfix16K_80000 (0x258): 
MTRRfix16K_A0000 (0x259): MTRRfix4K_C8000 (0x269): MTRRfix4K_D0000 0x26a: 
MTRRfix4K_D8000 0x26b: MTRRfix4K_E0000 0x26c: MTRRfix4K_E8000 0x26d: 
MTRRfix4K_F0000 0x26e: MTRRfix4K_F8000 0x26f: MTRRdefType (0x2ff):

So better return for those cases.

Signed-off-by: Jaswinder Singh Rajput <jaswinderraj...@gmail.com>
---
 mtrr.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/mtrr.c b/mtrr.c
index 32b5959..b948f67 100644
--- a/mtrr.c
+++ b/mtrr.c
@@ -20,11 +20,19 @@ static void dump_mtrr(int cpu, int msr)
 
 void dump_mtrrs(struct cpudata *cpu)
 {
+       unsigned long long val = 0;
        unsigned int i;
 
        if (!(cpu->flags_edx & (X86_FEATURE_MTRR)))
                return;
 
+       /*
+        * If MTRR registers are not accessible like in some
+        * virtualization systems then return
+        */
+       if (!read_msr(cpu->number, 0xfe, &val))
+               return;
+
        printf("MTRR registers:\n");
 
        printf("MTRRcap (0xfe): ");
-- 
1.6.0.6



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