Merge branch 'x86-cpufeature-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cpufeature updates from Ingo Molnar:
 "The main changes in this cycle were related to enable ring-3
  MONITOR/MWAIT instructions support on supported CPUs, by Grzegorz
  Andrejczuk and Piotr Luc"

* 'x86-cpufeature-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpufeature: Move RING3MWAIT feature to avoid conflicts
  x86/cpufeature: Enable RING3MWAIT for Knights Mill
  x86/cpufeature: Enable RING3MWAIT for Knights Landing
  x86/cpufeature: Add RING3MWAIT to CPU features
  x86/elf: Add HWCAP2 to expose ring 3 MONITOR/MWAIT
  x86/msr: Add MSR_MISC_FEATURE_ENABLES and RING3MWAIT bit
  x86/cpufeature: Add AVX512_VPOPCNTDQ feature

1 files changed, 44 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 026c728d6ba7..017ecd3bb553 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -15,6 +15,8 @@
 #include <asm/cpu.h>
 #include <asm/intel-family.h>
 #include <asm/microcode_intel.h>
+#include <asm/hwcap2.h>
+#include <asm/elf.h>
 
 #ifdef CONFIG_X86_64
 #include <linux/topology.h>
@@ -62,6 +64,46 @@ void check_mpx_erratum(struct cpuinfo_x86 *c)
 	}
 }
 
+static bool ring3mwait_disabled __read_mostly;
+
+static int __init ring3mwait_disable(char *__unused)
+{
+	ring3mwait_disabled = true;
+	return 0;
+}
+__setup("ring3mwait=disable", ring3mwait_disable);
+
+static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c)
+{
+	/*
+	 * Ring 3 MONITOR/MWAIT feature cannot be detected without
+	 * cpu model and family comparison.
+	 */
+	if (c->x86 != 6)
+		return;
+	switch (c->x86_model) {
+	case INTEL_FAM6_XEON_PHI_KNL:
+	case INTEL_FAM6_XEON_PHI_KNM:
+		break;
+	default:
+		return;
+	}
+
+	if (ring3mwait_disabled) {
+		msr_clear_bit(MSR_MISC_FEATURE_ENABLES,
+			      MSR_MISC_FEATURE_ENABLES_RING3MWAIT_BIT);
+		return;
+	}
+
+	msr_set_bit(MSR_MISC_FEATURE_ENABLES,
+		    MSR_MISC_FEATURE_ENABLES_RING3MWAIT_BIT);
+
+	set_cpu_cap(c, X86_FEATURE_RING3MWAIT);
+
+	if (c == &boot_cpu_data)
+		ELF_HWCAP2 |= HWCAP2_RING3MWAIT;
+}
+
 static void early_init_intel(struct cpuinfo_x86 *c)
 {
 	u64 misc_enable;
@@ -562,6 +604,8 @@ static void init_intel(struct cpuinfo_x86 *c)
 		detect_vmx_virtcap(c);
 
 	init_intel_energy_perf(c);
+
+	probe_xeon_phi_r3mwait(c);
 }
 
 #ifdef CONFIG_X86_32