From: kettenis <kettenis@openbsd.org>
Date: Fri, 7 Jun 2024 16:53:35 +0000 (+0000)
Subject: Make sure we select the deepest possible C-state during suspend-to-idle.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=6c195505b1f995019b32baa30da27b6fe0eee39b;p=openbsd

Make sure we select the deepest possible C-state during suspend-to-idle.

ok deraadt@, guenther@, mlarkin@, jsg@
---

diff --git a/sys/arch/amd64/amd64/cpu.c b/sys/arch/amd64/amd64/cpu.c
index 6714c0237f9..8df6de03b89 100644
--- a/sys/arch/amd64/amd64/cpu.c
+++ b/sys/arch/amd64/amd64/cpu.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.c,v 1.189 2024/05/29 12:21:33 kettenis Exp $	*/
+/*	$OpenBSD: cpu.c,v 1.190 2024/06/07 16:53:35 kettenis Exp $	*/
 /* $NetBSD: cpu.c,v 1.1 2003/04/26 18:39:26 fvdl Exp $ */
 
 /*-
@@ -1469,7 +1469,10 @@ int cpu_suspended;
 void
 cpu_suspend_cycle(void)
 {
-	cpu_idle_cycle_fcn();
+	if (cpu_suspend_cycle_fcn)
+		cpu_suspend_cycle_fcn();
+	else
+		cpu_idle_cycle_fcn();
 }
 
 int
diff --git a/sys/arch/amd64/amd64/ipifuncs.c b/sys/arch/amd64/amd64/ipifuncs.c
index 5c330d7a139..482fc9eebb4 100644
--- a/sys/arch/amd64/amd64/ipifuncs.c
+++ b/sys/arch/amd64/amd64/ipifuncs.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ipifuncs.c,v 1.38 2023/10/30 12:50:59 mvs Exp $	*/
+/*	$OpenBSD: ipifuncs.c,v 1.39 2024/06/07 16:53:35 kettenis Exp $	*/
 /*	$NetBSD: ipifuncs.c,v 1.1 2003/04/26 18:39:28 fvdl Exp $ */
 
 /*-
@@ -128,7 +128,10 @@ x86_64_ipi_halt(struct cpu_info *ci)
 	wbinvd();
 
 	for(;;) {
-		__asm volatile("hlt");
+		if (cpu_suspend_cycle_fcn)
+			cpu_suspend_cycle_fcn();
+		else
+			__asm volatile("hlt");
 	}
 }
 
diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index 343cc0f7e52..35cea0b5810 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.293 2024/04/29 00:29:48 jsg Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.294 2024/06/07 16:53:35 kettenis Exp $	*/
 /*	$NetBSD: machdep.c,v 1.3 2003/05/07 22:58:18 fvdl Exp $	*/
 
 /*-
@@ -162,6 +162,7 @@ char machine[] = MACHINE;
  */
 void cpu_idle_cycle_hlt(void);
 void (*cpu_idle_cycle_fcn)(void) = &cpu_idle_cycle_hlt;
+void (*cpu_suspend_cycle_fcn)(void);
 
 /* the following is used externally for concurrent handlers */
 int setperf_prio = 0;
diff --git a/sys/arch/amd64/include/cpu.h b/sys/arch/amd64/include/cpu.h
index fab34e5bd9d..90f5dd9e905 100644
--- a/sys/arch/amd64/include/cpu.h
+++ b/sys/arch/amd64/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.171 2024/05/29 12:21:33 kettenis Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.172 2024/06/07 16:53:35 kettenis Exp $	*/
 /*	$NetBSD: cpu.h,v 1.1 2003/04/26 18:39:39 fvdl Exp $	*/
 
 /*-
@@ -420,6 +420,7 @@ void	cpu_proc_fork(struct proc *, struct proc *);
 int	amd64_pa_used(paddr_t);
 #define	cpu_idle_enter()	do { /* nothing */ } while (0)
 extern void (*cpu_idle_cycle_fcn)(void);
+extern void (*cpu_suspend_cycle_fcn)(void);
 #define	cpu_idle_cycle()	(*cpu_idle_cycle_fcn)()
 #define	cpu_idle_leave()	do { /* nothing */ } while (0)
 extern void (*initclock_func)(void);
diff --git a/sys/arch/i386/i386/machdep.c b/sys/arch/i386/i386/machdep.c
index a75259a7474..49999ca6685 100644
--- a/sys/arch/i386/i386/machdep.c
+++ b/sys/arch/i386/i386/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.671 2024/05/26 13:37:32 kettenis Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.672 2024/06/07 16:53:35 kettenis Exp $	*/
 /*	$NetBSD: machdep.c,v 1.214 1996/11/10 03:16:17 thorpej Exp $	*/
 
 /*-
@@ -167,6 +167,7 @@ char machine[] = MACHINE;
 void (*cpu_idle_leave_fcn)(void) = NULL;
 void (*cpu_idle_cycle_fcn)(void) = NULL;
 void (*cpu_idle_enter_fcn)(void) = NULL;
+void (*cpu_suspend_cycle_fcn)(void);
 
 
 struct uvm_constraint_range  isa_constraint = { 0x0, 0x00ffffffUL };
diff --git a/sys/arch/i386/include/cpu.h b/sys/arch/i386/include/cpu.h
index 1c2d693846c..565f6159c74 100644
--- a/sys/arch/i386/include/cpu.h
+++ b/sys/arch/i386/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.189 2024/05/21 23:16:06 jsg Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.190 2024/06/07 16:53:35 kettenis Exp $	*/
 /*	$NetBSD: cpu.h,v 1.35 1996/05/05 19:29:26 christos Exp $	*/
 
 /*-
@@ -375,6 +375,7 @@ extern const struct cpu_cpuid_nameclass i386_cpuid_cpus[];
 extern void (*cpu_idle_enter_fcn)(void);
 extern void (*cpu_idle_cycle_fcn)(void);
 extern void (*cpu_idle_leave_fcn)(void);
+extern void (*cpu_suspend_cycle_fcn)(void);
 
 extern int cpuspeed;
 
diff --git a/sys/dev/acpi/acpicpu.c b/sys/dev/acpi/acpicpu.c
index 0a5ee1fea7d..6a126faddf1 100644
--- a/sys/dev/acpi/acpicpu.c
+++ b/sys/dev/acpi/acpicpu.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: acpicpu.c,v 1.92 2022/04/06 18:59:27 naddy Exp $ */
+/* $OpenBSD: acpicpu.c,v 1.93 2024/06/07 16:53:35 kettenis Exp $ */
 /*
  * Copyright (c) 2005 Marco Peereboom <marco@openbsd.org>
  * Copyright (c) 2015 Philip Guenther <guenther@openbsd.org>
@@ -172,6 +172,7 @@ void	acpicpu_add_cstate(struct acpicpu_softc *_sc, int _state, int _method,
 	    int _flags, int _latency, int _power, uint64_t _address);
 void	acpicpu_set_pdc(struct acpicpu_softc *);
 void	acpicpu_idle(void);
+void	acpicpu_suspend(void);
 
 #if 0
 void    acpicpu_set_throttle(struct acpicpu_softc *, int);
@@ -747,6 +748,7 @@ acpicpu_attach(struct device *parent, struct device *self, void *aux)
 		extern uint32_t acpi_force_bm;
 
 		cpu_idle_cycle_fcn = &acpicpu_idle;
+		cpu_suspend_cycle_fcn = &acpicpu_suspend;
 
 		/*
 		 * C3 (and maybe C2?) needs BM_RLD to be set to
@@ -1277,3 +1279,66 @@ acpicpu_idle(void)
 	sc->sc_prev_sleep = (sc->sc_prev_sleep + (sc->sc_prev_sleep >> 1)
 	    + itime) >> 1;
 }
+
+void
+acpicpu_suspend(void)
+{
+	extern int cpu_suspended;
+	struct cpu_info *ci = curcpu();
+	struct acpicpu_softc *sc = (struct acpicpu_softc *)ci->ci_acpicpudev;
+	struct acpi_cstate *best, *cx;
+
+	if (sc == NULL) {
+		__asm volatile("sti");
+		panic("null acpicpu");
+	}
+
+	/*
+	 * Find the lowest usable state.
+	 */
+	best = cx = SLIST_FIRST(&sc->sc_cstates);
+	while ((cx->flags & CST_FLAG_SKIP)) {
+		if ((cx = SLIST_NEXT(cx, link)) == NULL)
+			break;
+		best = cx;
+	}
+
+	switch (best->method) {
+	default:
+	case CST_METH_HALT:
+		__asm volatile("sti; hlt");
+		break;
+
+	case CST_METH_IO_HALT:
+		inb((u_short)best->address);
+		__asm volatile("sti; hlt");
+		break;
+
+	case CST_METH_MWAIT:
+		{
+		unsigned int hints;
+
+		hints = (unsigned)best->address;
+		/* intel errata AAI65: cflush before monitor */
+		if (ci->ci_cflushsz != 0 &&
+		    strcmp(cpu_vendor, "GenuineIntel") == 0) {
+			membar_sync();
+			clflush((unsigned long)&cpu_suspended);
+			membar_sync();
+		}
+
+		monitor(&cpu_suspended, 0, 0);
+		if (cpu_suspended || !CPU_IS_PRIMARY(ci))
+			mwait(0, hints);
+
+		break;
+		}
+
+	case CST_METH_GAS_IO:
+		inb((u_short)best->address);
+		/* something harmless to give system time to change state */
+		acpi_read_pmreg(acpi_softc, ACPIREG_PM1_STS, 0);
+		break;
+
+	}
+}