x86: detect mwait capabilities and extensions, when present

Reviewed by:	kib (earlier amd64-only version)
MFC after:	2 weeks

3 files changed, 13 insertions, 0 deletions

diff --git a/sys/amd64/amd64/identcpu.c b/sys/amd64/amd64/identcpu.c
index e63affc..27ea9a6 100644
--- a/sys/amd64/amd64/identcpu.c
+++ b/sys/amd64/amd64/identcpu.c
@@ -532,6 +532,13 @@ identify_cpu(void)
 		}
 	}
 
+	if (cpu_high >= 5 && (cpu_feature2 & CPUID2_MON) != 0) {
+		do_cpuid(5, regs);
+		cpu_mon_mwait_flags = regs[2];
+		cpu_mon_min_size = regs[0] &  CPUID5_MON_MIN_SIZE;
+		cpu_mon_max_size = regs[1] &  CPUID5_MON_MAX_SIZE;
+	}
+
 	if (cpu_high >= 7) {
 		cpuid_count(7, 0, regs);
 		cpu_stdext_feature = regs[1];
diff --git a/sys/amd64/amd64/initcpu.c b/sys/amd64/amd64/initcpu.c
index 4abed4c..f7574b1 100644
--- a/sys/amd64/amd64/initcpu.c
+++ b/sys/amd64/amd64/initcpu.c
@@ -75,6 +75,9 @@ u_int	cpu_mxcsr_mask;		/* Valid bits in mxcsr */
 u_int	cpu_clflush_line_size = 32;
 u_int	cpu_stdext_feature;
 u_int	cpu_max_ext_state_size;
+u_int	cpu_mon_mwait_flags;	/* MONITOR/MWAIT flags (CPUID.05H.ECX) */
+u_int	cpu_mon_min_size;	/* MONITOR minimum range size, bytes */
+u_int	cpu_mon_max_size;	/* MONITOR minimum range size, bytes */
 
 SYSCTL_UINT(_hw, OID_AUTO, via_feature_rng, CTLFLAG_RD,
 	&via_feature_rng, 0, "VIA RNG feature available in CPU");
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
index 6ffcf63..34bfde4 100644
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -58,6 +58,9 @@ extern	u_int	cpu_procinfo;
 extern	u_int	cpu_procinfo2;
 extern	char	cpu_vendor[];
 extern	u_int	cpu_vendor_id;
+extern	u_int	cpu_mon_mwait_flags;
+extern	u_int	cpu_mon_min_size;
+extern	u_int	cpu_mon_max_size;
 extern	char	ctx_switch_xsave[];
 extern	char	kstack[];
 extern	char	sigcode[];