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authorAndreas Herrmann <andreas.herrmann3@amd.com>2012-04-03 12:13:07 +0200
committerIngo Molnar <mingo@kernel.org>2012-04-27 16:43:09 +0200
commitf7f286a910221ae18b21c18d9d0f4cd88965829f (patch)
treee2bb2aef9e9507f8b309b1ede63b2ea862d0f1ee
parentea0dcf903e7d76aa5d483d876215fedcfdfe140f (diff)
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x86/amd: Re-enable CPU topology extensions in case BIOS has disabled it
BIOS will switch off the corresponding feature flag on family 15h models 10h-1fh non-desktop CPUs. The topology extension CPUID leafs are required to detect which cores belong to the same compute unit. (thread siblings mask is set accordingly and also correct information about L1i and L2 cache sharing depends on this). W/o this patch we wouldn't see which cores belong to the same compute unit and also cache sharing information for L1i and L2 would be incorrect on such systems. Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/kernel/cpu/amd.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 1c67ca1..146bb62 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -580,6 +580,24 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
}
}
+ /* re-enable TopologyExtensions if switched off by BIOS */
+ if ((c->x86 == 0x15) &&
+ (c->x86_model >= 0x10) && (c->x86_model <= 0x1f) &&
+ !cpu_has(c, X86_FEATURE_TOPOEXT)) {
+ u64 val;
+
+ if (!rdmsrl_amd_safe(0xc0011005, &val)) {
+ val |= 1ULL << 54;
+ wrmsrl_amd_safe(0xc0011005, val);
+ rdmsrl(0xc0011005, val);
+ if (val & (1ULL << 54)) {
+ set_cpu_cap(c, X86_FEATURE_TOPOEXT);
+ printk(KERN_INFO FW_INFO "CPU: Re-enabling "
+ "disabled Topology Extensions Support\n");
+ }
+ }
+ }
+
cpu_detect_cache_sizes(c);
/* Multi core CPU? */
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