x86/mwait-idle: add Sierra Forest SoC support

Add Sierra Forest SoC C-states, which are C1, C1E, C6S, and C6SP.

Sierra Forest SoC is built with modules, each module includes 4 cores
(Crestmont microarchitecture). There is one L2 cache per module, shared
between the 4 cores.

There is no core C6 state, but there is C6S state, which has module scope:
when all 4 cores request C6S, the entire module (4 cores + L2 cache)
enters the low power state.

C6SP state has package scope - when all modules in the package enter C6S,
the package enters the power state mode.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Origin: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 92813fd5b156
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

xen/arch/x86/cpu/mwait-idle.c

@@ -950,6 +950,34 @@ static const struct cpuidle_state grr_cstates[] = {
 	{}
 };
 
+static const struct cpuidle_state srf_cstates[] = {
+	{
+		.name = "C1",
+		.flags = MWAIT2flg(0x00),
+		.exit_latency = 1,
+		.target_residency = 1,
+	},
+	{
+		.name = "C1E",
+		.flags = MWAIT2flg(0x01),
+		.exit_latency = 2,
+		.target_residency = 10,
+	},
+	{
+		.name = "C6S",
+		.flags = MWAIT2flg(0x22) | CPUIDLE_FLAG_TLB_FLUSHED,
+		.exit_latency = 270,
+		.target_residency = 700,
+	},
+	{
+		.name = "C6SP",
+		.flags = MWAIT2flg(0x23) | CPUIDLE_FLAG_TLB_FLUSHED,
+		.exit_latency = 310,
+		.target_residency = 900,
+	},
+	{}
+};
+
 static void cf_check mwait_idle(void)
 {
 	unsigned int cpu = smp_processor_id();
@@ -1199,6 +1227,11 @@ static const struct idle_cpu idle_cpu_grr = {
 	.c1e_promotion = C1E_PROMOTION_DISABLE,
 };
 
+static const struct idle_cpu idle_cpu_srf = {
+	.state_table = srf_cstates,
+	.c1e_promotion = C1E_PROMOTION_DISABLE,
+};
+
 #define ICPU(model, cpu) \
 	{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ ## model, X86_FEATURE_ALWAYS, \
 	  &idle_cpu_ ## cpu}
@@ -1248,6 +1281,7 @@ static const struct x86_cpu_id intel_idle_ids[] __initconstrel = {
 	ICPU(ATOM_GOLDMONT_D,		dnv),
 	ICPU(ATOM_TREMONT_D,		snr),
 	ICPU(ATOM_CRESTMONT,		grr),
+	ICPU(ATOM_CRESTMONT_X,		srf),
 	{}
 };