mwait-idle: add BXT support

Broxton has all the HSW C-states, except C3.
BXT C-state timing is slightly different.

Here we trust the IRTL MSRs as authority
on maximum C-state latency, and override the driver's tables
with the values found in the associated IRTL MSRs.
Further we set the target_residency to 1x maximum latency,
trusting the hardware demotion logic.

Signed-off-by: Len Brown <len.brown@intel.com>
[Linux commit: 5dcef694860100fd16885f052591b1268b764d21]
Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -612,6 +612,52 @@ static const struct cpuidle_state knl_cs
 	{}
 };
 
+static struct cpuidle_state bxt_cstates[] = {
+	{
+		.name = "C1-BXT",
+		.flags = MWAIT2flg(0x00),
+		.exit_latency = 2,
+		.target_residency = 2,
+	},
+	{
+		.name = "C1E-BXT",
+		.flags = MWAIT2flg(0x01),
+		.exit_latency = 10,
+		.target_residency = 20,
+	},
+	{
+		.name = "C6-BXT",
+		.flags = MWAIT2flg(0x20) | CPUIDLE_FLAG_TLB_FLUSHED,
+		.exit_latency = 133,
+		.target_residency = 133,
+	},
+	{
+		.name = "C7s-BXT",
+		.flags = MWAIT2flg(0x31) | CPUIDLE_FLAG_TLB_FLUSHED,
+		.exit_latency = 155,
+		.target_residency = 155,
+	},
+	{
+		.name = "C8-BXT",
+		.flags = MWAIT2flg(0x40) | CPUIDLE_FLAG_TLB_FLUSHED,
+		.exit_latency = 1000,
+		.target_residency = 1000,
+	},
+	{
+		.name = "C9-BXT",
+		.flags = MWAIT2flg(0x50) | CPUIDLE_FLAG_TLB_FLUSHED,
+		.exit_latency = 2000,
+		.target_residency = 2000,
+	},
+	{
+		.name = "C10-BXT",
+		.flags = MWAIT2flg(0x60) | CPUIDLE_FLAG_TLB_FLUSHED,
+		.exit_latency = 10000,
+		.target_residency = 10000,
+	},
+	{}
+};
+
 static void mwait_idle(void)
 {
 	unsigned int cpu = smp_processor_id();
@@ -793,11 +839,16 @@ static const struct idle_cpu idle_cpu_kn
 	.state_table = knl_cstates,
 };
 
+static const struct idle_cpu idle_cpu_bxt = {
+	.state_table = bxt_cstates,
+	.disable_promotion_to_c1e = 1,
+};
+
 #define ICPU(model, cpu) \
     { X86_VENDOR_INTEL, 6, model, X86_FEATURE_MONITOR, \
         &idle_cpu_##cpu}
 
-static const struct x86_cpu_id intel_idle_ids[] __initconst = {
+static const struct x86_cpu_id intel_idle_ids[] __initconstrel = {
 	ICPU(0x1a, nehalem),
 	ICPU(0x1e, nehalem),
 	ICPU(0x1f, nehalem),
@@ -829,6 +880,7 @@ static const struct x86_cpu_id intel_idl
 	ICPU(0x9e, skl),
 	ICPU(0x55, skx),
 	ICPU(0x57, knl),
+	ICPU(0x5c, bxt),
 	{}
 };
 
@@ -860,6 +912,72 @@ static void __init ivt_idle_state_table_
 }
 
 /*
+ * Translate IRTL (Interrupt Response Time Limit) MSR to usec
+ */
+
+static const unsigned int __initconst irtl_ns_units[] = {
+	1, 32, 1024, 32768, 1048576, 33554432, 0, 0 };
+
+static unsigned long long __init irtl_2_usec(unsigned long long irtl)
+{
+	unsigned long long ns;
+
+	ns = irtl_ns_units[(irtl >> 10) & 0x3];
+
+	return (irtl & 0x3FF) * ns / 1000;
+}
+/*
+ * bxt_idle_state_table_update(void)
+ *
+ * On BXT, we trust the IRTL to show the definitive maximum latency
+ * We use the same value for target_residency.
+ */
+static void __init bxt_idle_state_table_update(void)
+{
+	unsigned long long msr;
+
+	rdmsrl(MSR_PKGC6_IRTL, msr);
+	if (msr) {
+		unsigned int usec = irtl_2_usec(msr);
+
+		bxt_cstates[2].exit_latency = usec;
+		bxt_cstates[2].target_residency = usec;
+	}
+
+	rdmsrl(MSR_PKGC7_IRTL, msr);
+	if (msr) {
+		unsigned int usec = irtl_2_usec(msr);
+
+		bxt_cstates[3].exit_latency = usec;
+		bxt_cstates[3].target_residency = usec;
+	}
+
+	rdmsrl(MSR_PKGC8_IRTL, msr);
+	if (msr) {
+		unsigned int usec = irtl_2_usec(msr);
+
+		bxt_cstates[4].exit_latency = usec;
+		bxt_cstates[4].target_residency = usec;
+	}
+
+	rdmsrl(MSR_PKGC9_IRTL, msr);
+	if (msr) {
+		unsigned int usec = irtl_2_usec(msr);
+
+		bxt_cstates[5].exit_latency = usec;
+		bxt_cstates[5].target_residency = usec;
+	}
+
+	rdmsrl(MSR_PKGC10_IRTL, msr);
+	if (msr) {
+		unsigned int usec = irtl_2_usec(msr);
+
+		bxt_cstates[6].exit_latency = usec;
+		bxt_cstates[6].target_residency = usec;
+	}
+}
+
+/*
  * sklh_idle_state_table_update(void)
  *
  * On SKL-H (model 0x5e) disable C8 and C9 if:
@@ -907,6 +1025,9 @@ static void __init mwait_idle_state_tabl
 	case 0x3e: /* IVT */
 		ivt_idle_state_table_update();
 		break;
+	case 0x5c: /* BXT */
+		bxt_idle_state_table_update();
+		break;
 	case 0x5e: /* SKL-H */
 		sklh_idle_state_table_update();
 		break;
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -501,4 +501,12 @@
 #define MSR_CC6_DEMOTION_POLICY_CONFIG	0x00000668
 #define MSR_MC6_DEMOTION_POLICY_CONFIG	0x00000669
 
+/* Interrupt Response Limit */
+#define MSR_PKGC3_IRTL			0x0000060a
+#define MSR_PKGC6_IRTL			0x0000060b
+#define MSR_PKGC7_IRTL			0x0000060c
+#define MSR_PKGC8_IRTL			0x00000633
+#define MSR_PKGC9_IRTL			0x00000634
+#define MSR_PKGC10_IRTL			0x00000635
+
 #endif /* __ASM_MSR_INDEX_H */