[PATCH v2 4/4] Add R3MWAIT to CPU features

From: Grzegorz Andrejczuk
Date: Wed Oct 12 2016 - 08:19:55 EST


Add cpu feature for ring 3 monitor/mwait.

Change-Id: Iba4d20639efd8d3637d37db9294cbc43a98f009a
Signed-off-by: Grzegorz Andrejczuk <grzegorz.andrejczuk@xxxxxxxxx>
---
arch/x86/include/asm/cpufeatures.h | 2 ++
arch/x86/kernel/cpu/common.c | 3 +++
arch/x86/kernel/cpu/scattered.c | 5 +++++
3 files changed, 10 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 92a8308..9caf9c4 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -71,6 +71,8 @@
#define X86_FEATURE_RECOVERY ( 2*32+ 0) /* CPU in recovery mode */
#define X86_FEATURE_LONGRUN ( 2*32+ 1) /* Longrun power control */
#define X86_FEATURE_LRTI ( 2*32+ 3) /* LongRun table interface */
+/* non architectural Intel-defined CPU features not present in CPUID */
+#define X86_FEATURE_PHIR3MWAIT (2*32+ 4)

/* Other features, Linux-defined mapping, word 3 */
/* This range is used for feature bits which conflict or are synthesized */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 93ffaa5..15fe27f 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1108,6 +1108,9 @@ static void identify_cpu(struct cpuinfo_x86 *c)
#endif
/* The boot/hotplug time assigment got cleared, restore it */
c->logical_proc_id = topology_phys_to_logical_pkg(c->phys_proc_id);
+
+ if (cpu_has(c, X86_FEATURE_PHIR3MWAIT))
+ elf_hwcap2 |= HWCAP2_PHIR3MWAIT;
}

/*
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index 8cb57df..e4ff3d0 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -29,6 +29,7 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
u32 max_level;
u32 regs[4];
const struct cpuid_bit *cb;
+ u64 misc_thd_enable;

static const struct cpuid_bit cpuid_bits[] = {
{ X86_FEATURE_INTEL_PT, CR_EBX,25, 0x00000007, 0 },
@@ -54,4 +55,8 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
if (regs[cb->reg] & (1 << cb->bit))
set_cpu_cap(c, cb->feature);
}
+
+ rdmsrl(MSR_PHI_MISC_THD_FEATURE, misc_thd_enable);
+ if ((misc_thd_enable & MSR_PHI_MISC_THD_FEATURE_R3MWAIT) != 0)
+ set_cpu_cap(c, X86_FEATURE_PHIR3MWAIT);
}
--
2.5.1