From: Sepherosa Ziehau <sephe@dragonflybsd.org>
Date: Wed, 14 Mar 2012 03:18:44 +0000 (+0800)
Subject: ioapic: By default, disable I/O APIC if we are booting on a virtual machine
X-Git-Tag: v3.2.0~1254
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/e6dee92888cc1f1ee52d36053fabf97cfd2f9518

ioapic: By default, disable I/O APIC if we are booting on a virtual machine

I/O APIC causes too much trouble on virtual machines; simply disable
I/O APIC for virtual machines by default.

You could always explicitly enable I/O APIC on virtual machines by
setting tunable hw.ioapic_enable to 1

Thank swildner@ for hint on virtual machine detection method.

Reported-by: many
---

diff --git a/sys/platform/pc32/apic/ioapic.c b/sys/platform/pc32/apic/ioapic.c
index 55db0e19e6..18d06f1e62 100644
--- a/sys/platform/pc32/apic/ioapic.c
+++ b/sys/platform/pc32/apic/ioapic.c
@@ -80,7 +80,7 @@ static struct ioapic_conf	ioapic_conf;
 static TAILQ_HEAD(, ioapic_enumerator) ioapic_enumerators =
 	TAILQ_HEAD_INITIALIZER(ioapic_enumerators);
 
-int		ioapic_enable = 1; /* I/O APIC is enabled by default */
+int		ioapic_enable = -1; /* I/O APIC auto-enable mode */
 
 static int
 ioapic_config(void)
diff --git a/sys/platform/pc32/i386/machdep.c b/sys/platform/pc32/i386/machdep.c
index 85c18db43a..6864c51c77 100644
--- a/sys/platform/pc32/i386/machdep.c
+++ b/sys/platform/pc32/i386/machdep.c
@@ -1952,6 +1952,19 @@ init386(int first)
 	TUNABLE_INT_FETCH("hw.ioapic_enable", &ioapic_enable);
 	TUNABLE_INT_FETCH("hw.lapic_enable", &lapic_enable);
 
+	/*
+	 * Some of the virtaul machines do not work w/ I/O APIC
+	 * enabled.  If the user does not explicitly enable or
+	 * disable the I/O APIC (ioapic_enable < 0), then we
+	 * disable I/O APIC on all virtual machines.
+	 */
+	if (ioapic_enable < 0) {
+		if (cpu_feature2 & CPUID2_VMM)
+			ioapic_enable = 0;
+		else
+			ioapic_enable = 1;
+	}
+
 	/*
 	 * start with one cpu.  Note: with one cpu, ncpus2_shift, ncpus2_mask,
 	 * and ncpus_fit_mask remain 0.
diff --git a/sys/platform/pc64/apic/ioapic.c b/sys/platform/pc64/apic/ioapic.c
index a1e6709d6f..6065205594 100644
--- a/sys/platform/pc64/apic/ioapic.c
+++ b/sys/platform/pc64/apic/ioapic.c
@@ -80,7 +80,7 @@ static struct ioapic_conf	ioapic_conf;
 static TAILQ_HEAD(, ioapic_enumerator) ioapic_enumerators =
 	TAILQ_HEAD_INITIALIZER(ioapic_enumerators);
 
-int		ioapic_enable = 1; /* I/O APIC is enabled by default */
+int		ioapic_enable = -1; /* I/O APIC auto-enable mode */
 
 static int
 ioapic_config(void)
diff --git a/sys/platform/pc64/x86_64/machdep.c b/sys/platform/pc64/x86_64/machdep.c
index ac879b73dd..4260785e24 100644
--- a/sys/platform/pc64/x86_64/machdep.c
+++ b/sys/platform/pc64/x86_64/machdep.c
@@ -1795,10 +1795,6 @@ hammer_time(u_int64_t modulep, u_int64_t physfree)
 	 */
 	MachIntrABI = MachIntrABI_ICU;
 
-	TUNABLE_INT_FETCH("hw.apic_io_enable", &ioapic_enable); /* for compat */
-	TUNABLE_INT_FETCH("hw.ioapic_enable", &ioapic_enable);
-	TUNABLE_INT_FETCH("hw.lapic_enable", &lapic_enable);
-
 	/*
 	 * start with one cpu.  Note: with one cpu, ncpus2_shift, ncpus2_mask,
 	 * and ncpus_fit_mask remain 0.
@@ -1910,6 +1906,27 @@ hammer_time(u_int64_t modulep, u_int64_t physfree)
 	identify_cpu();		/* Final stage of CPU initialization */
 	initializecpu();	/* Initialize CPU registers */
 
+	TUNABLE_INT_FETCH("hw.apic_io_enable", &ioapic_enable); /* for compat */
+	TUNABLE_INT_FETCH("hw.ioapic_enable", &ioapic_enable);
+	TUNABLE_INT_FETCH("hw.lapic_enable", &lapic_enable);
+
+	/*
+	 * Some of the virtaul machines do not work w/ I/O APIC
+	 * enabled.  If the user does not explicitly enable or
+	 * disable the I/O APIC (ioapic_enable < 0), then we
+	 * disable I/O APIC on all virtual machines.
+	 *
+	 * NOTE:
+	 * This must be done after identify_cpu(), which sets
+	 * 'cpu_feature2'
+	 */
+	if (ioapic_enable < 0) {
+		if (cpu_feature2 & CPUID2_VMM)
+			ioapic_enable = 0;
+		else
+			ioapic_enable = 1;
+	}
+
 	/* make an initial tss so cpu can get interrupt stack on syscall! */
 	gd->gd_common_tss.tss_rsp0 =
 		(register_t)(thread0.td_kstack +