From: ddugger@redhat.com <ddugger@redhat.com>
Date: Tue, 21 Apr 2009 13:01:34 -0600
Subject: [xen] enable systems without APIC
Message-id: 200904211901.n3LJ1Y7C028407@sobek.n0ano.com
O-Subject: [RHEL5.4 PATCH 5/6 V2] BZ496873: xen: enable systems without APIC
Bugzilla: 496873
RH-Acked-by: Rik van Riel <riel@redhat.com>
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
RH-Acked-by: Justin M. Forbes <jforbes@redhat.com>

	x86: restore ability to work on systems without APIC

	This got broken with the default-enabling of MSI. Apart from fixing
	the base issue, the patch also addresses
	- the 'i' command crashing where there is no IO-APIC,
	- the 'i' command needlessly printing information for all 256 vectors
	  when the use of IO-APIC(s) is disabled, and
	- the need to specify both "nolapic" and "noapic" when "nolapic" alone
	  should already have the intended effect.

Upstream status: accepted (CS 19038)

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Qing He <qing.he@intel.com>
Signed-off-by: Gerd Hoffman <kraxel@redhat.com>
Signed-off-by: Don Dugger <donald.d.dugger@intel.com>

Yet Another Resend - resolve the conflicting BZs between the Subject line
(correct) and the message body (incorrect).

diff --git a/arch/x86/apic.c b/arch/x86/apic.c
index 85f5126..ee531c8 100644
--- a/arch/x86/apic.c
+++ b/arch/x86/apic.c
@@ -40,7 +40,7 @@
 /*
  * Knob to control our willingness to enable the local APIC.
  */
-int enable_local_apic __initdata = 0; /* -1=force-disable, +1=force-enable */
+static int enable_local_apic __initdata = 0; /* -1=force-disable, +1=force-enable */
 
 /*
  * Debug level
@@ -704,7 +704,7 @@ static void apic_pm_activate(void)
 static void __init lapic_disable(char *str)
 {
     enable_local_apic = -1;
-    clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
+    setup_clear_cpu_cap(X86_FEATURE_APIC);
 }
 custom_param("nolapic", lapic_disable);
 
diff --git a/arch/x86/cpu/common.c b/arch/x86/cpu/common.c
index 5e02243..9490f59 100644
--- a/arch/x86/cpu/common.c
+++ b/arch/x86/cpu/common.c
@@ -29,6 +29,14 @@ struct cpu_dev * cpu_devs[X86_VENDOR_NUM] = {};
  */
 u64 host_pat = 0x050100070406;
 
+static unsigned int __cpuinitdata cleared_caps[NCAPINTS];
+
+void __init setup_clear_cpu_cap(unsigned int cap)
+{
+	__clear_bit(cap, boot_cpu_data.x86_capability);
+	__set_bit(cap, cleared_caps);
+}
+
 static void default_init(struct cpuinfo_x86 * c)
 {
 	/* Not much we can do here... */
@@ -226,6 +234,7 @@ static void __init early_cpu_detect(void)
 		if (c->x86 >= 0x6)
 			c->x86_model += ((tfms >> 16) & 0xF) << 4;
 		c->x86_mask = tfms & 15;
+		cap0 &= ~cleared_caps[0];
 		if (cap0 & (1<<19))
 			c->x86_cache_alignment = ((misc >> 8) & 0xff) * 8;
 		c->x86_capability[0] = cap0; /* Added for Xen bootstrap */
@@ -384,6 +393,9 @@ void __devinit identify_cpu(struct cpuinfo_x86 *c)
 	if (disable_pse)
 		clear_bit(X86_FEATURE_PSE, c->x86_capability);
 
+	for (i = 0 ; i < NCAPINTS ; ++i)
+		c->x86_capability[i] &= ~cleared_caps[i];
+
 	/* If the model name is still unset, do table lookup. */
 	if ( !c->x86_model_id[0] ) {
 		char *p;
diff --git a/arch/x86/io_apic.c b/arch/x86/io_apic.c
index c450b16..87ca431 100644
--- a/arch/x86/io_apic.c
+++ b/arch/x86/io_apic.c
@@ -84,7 +84,9 @@ int disable_timer_pin_1 __initdata;
 
 static struct irq_pin_list {
     int apic, pin, next;
-} irq_2_pin[PIN_MAP_SIZE];
+} irq_2_pin[PIN_MAP_SIZE] = {
+    [0 ... PIN_MAP_SIZE-1].pin = -1
+};
 static int irq_2_pin_free_entry = NR_IRQS;
 
 int vector_irq[NR_VECTORS] __read_mostly = {
@@ -1018,11 +1020,6 @@ static void __init enable_IO_APIC(void)
     int i, apic;
     unsigned long flags;
 
-    for (i = 0; i < PIN_MAP_SIZE; i++) {
-        irq_2_pin[i].pin = -1;
-        irq_2_pin[i].next = 0;
-    }
-
     /* Initialise dynamic irq_2_pin free list. */
     for (i = NR_IRQS; i < PIN_MAP_SIZE; i++)
         irq_2_pin[i].next = i + 1;
diff --git a/arch/x86/irq.c b/arch/x86/irq.c
index d1bc8a0..cb40528 100644
--- a/arch/x86/irq.c
+++ b/arch/x86/irq.c
@@ -784,8 +784,8 @@ int map_domain_pirq(
         return -EINVAL;
     }
 
-    old_vector = d->arch.pirq_vector[pirq];
-    old_pirq = d->arch.vector_pirq[vector];
+    old_vector = domain_irq_to_vector(d, pirq);
+    old_pirq = domain_vector_to_irq(d, vector);
 
     if ( (old_vector && (old_vector != vector) ) ||
          (old_pirq && (old_pirq != pirq)) )
@@ -809,6 +809,10 @@ int map_domain_pirq(
     {
         struct msi_info *msi = (struct msi_info *)data;
 
+        ret = -ENODEV;
+        if ( !cpu_has_apic )
+            goto done;
+
         pdev = pci_get_pdev(msi->bus, msi->devfn);
         ret = pci_enable_msi(msi, &msi_desc);
         if ( ret )
@@ -854,7 +858,7 @@ int unmap_domain_pirq(struct domain *d, int pirq)
     ASSERT(spin_is_locked(&pcidevs_lock));
     ASSERT(spin_is_locked(&d->event_lock));
 
-    vector = d->arch.pirq_vector[pirq];
+    vector = domain_irq_to_vector(d, pirq);
     if ( vector <= 0 )
     {
         dprintk(XENLOG_G_ERR, "dom%d: pirq %d not mapped\n",
@@ -875,7 +879,7 @@ int unmap_domain_pirq(struct domain *d, int pirq)
 
     spin_lock_irqsave(&desc->lock, flags);
 
-    BUG_ON(vector != d->arch.pirq_vector[pirq]);
+    BUG_ON(vector != domain_irq_to_vector(d, pirq));
 
     if ( msi_desc )
         teardown_msi_vector(vector);
diff --git a/arch/x86/physdev.c b/arch/x86/physdev.c
index 7872e82..8485cca 100644
--- a/arch/x86/physdev.c
+++ b/arch/x86/physdev.c
@@ -101,14 +101,14 @@ static int physdev_map_pirq(struct physdev_map_pirq *map)
     spin_lock(&pcidevs_lock);
     /* Verify or get pirq. */
     spin_lock(&d->event_lock);
+    pirq = domain_vector_to_irq(d, vector);
     if ( map->pirq < 0 )
     {
-        if ( d->arch.vector_pirq[vector] )
+        if ( pirq )
         {
             dprintk(XENLOG_G_ERR, "dom%d: %d:%d already mapped to %d\n",
                     d->domain_id, map->index, map->pirq,
-                    d->arch.vector_pirq[vector]);
-            pirq = d->arch.vector_pirq[vector];
+                    pirq);
             if ( pirq < 0 )
             {
                 ret = -EBUSY;
@@ -128,8 +128,7 @@ static int physdev_map_pirq(struct physdev_map_pirq *map)
     }
     else
     {
-        if ( d->arch.vector_pirq[vector] &&
-             d->arch.vector_pirq[vector] != map->pirq )
+        if ( pirq && pirq != map->pirq )
         {
             dprintk(XENLOG_G_ERR, "dom%d: vector %d conflicts with irq %d\n",
                     d->domain_id, map->index, map->pirq);
diff --git a/include/asm-x86/irq.h b/include/asm-x86/irq.h
index ac90bbc..5941b33 100644
--- a/include/asm-x86/irq.h
+++ b/include/asm-x86/irq.h
@@ -59,8 +59,12 @@ int unmap_domain_pirq(struct domain *d, int pirq);
 int get_free_pirq(struct domain *d, int type, int index);
 void free_domain_pirqs(struct domain *d);
 
-#define domain_irq_to_vector(d, irq) ((d)->arch.pirq_vector[(irq)])
-#define domain_vector_to_irq(d, vec) ((d)->arch.vector_pirq[(vec)])
+#define domain_irq_to_vector(d, irq) ((d)->arch.pirq_vector[irq] ?: \
+                                      IO_APIC_IRQ(irq) ? 0 : LEGACY_VECTOR(irq))
+#define domain_vector_to_irq(d, vec) ((d)->arch.vector_pirq[vec] ?: \
+                                      ((vec) < FIRST_LEGACY_VECTOR || \
+                                       (vec) > LAST_LEGACY_VECTOR) ? \
+                                      0 : LEGACY_IRQ_FROM_VECTOR(vec))
 
 int pirq_guest_force_unbind(struct domain *d, int irq);
 
diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index 7e633e2..fad625c 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -196,6 +196,7 @@ extern int phys_proc_id[NR_CPUS];
 extern int cpu_core_id[NR_CPUS];
 
 extern void identify_cpu(struct cpuinfo_x86 *);
+extern void setup_clear_cpu_cap(unsigned int);
 extern void print_cpu_info(struct cpuinfo_x86 *);
 extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
 extern void dodgy_tsc(void);