[PATCH] x86info: mtrr.c return if MTRR registers are not accessible

[Jaswinder Singh Rajput <jaswinder@kernel.org>]

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 <jaswinderrajput@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