[PATCH] x86, cpu, amd: Use 8-bit extractor for NodeId field

Aravind Gopalakrishnan
2015-01-19T18:04:20Z

The NodeId field in cpuid_ecx(0x8000001e) is a 8 bit field.
Although current extractor works fine, it will break if/when
the most significant 5 bits ever get used.

So, lets honor the field as architected in the BKDG

Reference: BKDG for AMD Fam15h Models 00h-0fh,
CPUID Fn8000_001E_ECX Node Identifiers

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
---
arch/x86/kernel/cpu/amd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index a220239..9942b83 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -300,7 +300,7 @@ static void amd_get_topology(struct cpuinfo_x86 *c)

cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
nodes = ((ecx >> 8) & 7) + 1;
- node_id = ecx & 7;
+ node_id = ecx & 0xff;

/* get compute unit information */
smp_num_siblings = ((ebx >> 8) & 3) + 1;
--
1.9.1