Messages in this thread Patch in this message | | | From | Vikas Shivappa <> | Subject | [PATCH 6/7] x86/intel_rdt: Intel haswell CAT enumeration | Date | Tue, 24 Feb 2015 15:16:43 -0800 |
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CAT(Cache Allocation Technology) on hsw needs to be enumerated separately. CAT is only supported on certain HSW SKUs. This patch does a probe test for hsw CPUs by writing a CLOSid into high 32 bits of IA32_PQR_MSR and see if the bits stick. The probe test is only done after confirming that the CPU is HSW.
Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com> --- arch/x86/kernel/cpu/intel_rdt.c | 42 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+)
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c index 602c580..d61be19 100644 --- a/arch/x86/kernel/cpu/intel_rdt.c +++ b/arch/x86/kernel/cpu/intel_rdt.c @@ -38,11 +38,53 @@ DEFINE_PER_CPU(unsigned int, x86_cpu_clos); #define rdt_for_each_child(pos_css, parent_ir) \ css_for_each_child((pos_css), &(parent_ir)->css) +/* + * hsw_probetest() - Have to do probe + * test for Intel haswell CPUs as it does not have + * CPUID enumeration support for CAT. + * + * Probes by writing to the high 32 bits(CLOSid) + * of the IA32_PQR_MSR and testing if the bits stick. + * Then hardcode the max CLOS and max bitmask length on hsw. + */ + +static inline bool hsw_probetest(void) +{ + u32 l, h_old, h_new, h_tmp; + + if (rdmsr_safe(MSR_IA32_PQR_ASSOC, &l, &h_old)) + return false; + + /* + * Default value is always 0 if feature is present. + */ + h_tmp = h_old ^ 0x1U; + if (wrmsr_safe(MSR_IA32_PQR_ASSOC, l, h_tmp) || + rdmsr_safe(MSR_IA32_PQR_ASSOC, &l, &h_new)) + return false; + + if (h_tmp != h_new) + return false; + + wrmsr_safe(MSR_IA32_PQR_ASSOC, l, h_old); + + boot_cpu_data.x86_cat_closs = 4; + boot_cpu_data.x86_cat_cbmlength = 20; + + return true; +} + static inline bool cat_supported(struct cpuinfo_x86 *c) { if (cpu_has(c, X86_FEATURE_CAT_L3)) return true; + /* + * Probe test for Haswell CPUs. + */ + if (c->x86 == 6 && c->x86_model == 0x3f) + return hsw_probetest(); + return false; } -- 1.9.1
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