x2APIC: improve enabling logic

This patch masks PIC and IOAPIC RTE's before x2APIC enabling, unmask
and restore them after x2APIC enabling. It also really enables
interrupt remapping before x2APIC enabling instead of just checking
interrupt remapping setting. This patch also handles all x2APIC
configuration including BIOS settings and command line
settings. Especially, it handles that BIOS hands over in x2APIC mode
(when there is apic id > 255). It checks if x2APIC is already enabled
by BIOS. If already enabled, it will disable interrupt remapping and
queued invalidation first, then enable them again.

Signed-off-by: Weidong Han <weidong.han@intel.com>

1 files changed, 171 insertions, 19 deletions

diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
index 6a834b8292..844f46ff01 100644
--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -70,6 +70,9 @@ int apic_verbosity;
 int x2apic_enabled __read_mostly = 0;
 int directed_eoi_enabled __read_mostly = 0;
 
+/* x2APIC is enabled in BIOS */
+static int x2apic_preenabled;
+
 /*
  * The following vectors are part of the Linux architecture, there
  * is no hardware IRQ pin equivalent for them, they are triggered
@@ -489,6 +492,47 @@ static void apic_pm_activate(void)
     apic_pm_state.active = 1;
 }
 
+static void resume_x2apic(void)
+{
+    uint64_t msr_content;
+    struct IO_APIC_route_entry **ioapic_entries = NULL;
+
+    ASSERT(x2apic_enabled);
+
+    ioapic_entries = alloc_ioapic_entries();
+    if ( !ioapic_entries )
+    {
+        printk("Allocate ioapic_entries failed\n");
+        goto out;
+    }
+
+    if ( save_IO_APIC_setup(ioapic_entries) )
+    {
+        printk("Saving IO-APIC state failed\n");
+        goto out;
+    }
+
+    mask_8259A();
+    mask_IO_APIC_setup(ioapic_entries);
+
+    iommu_enable_IR();
+
+    rdmsrl(MSR_IA32_APICBASE, msr_content);
+    if ( !(msr_content & MSR_IA32_APICBASE_EXTD) )
+    {
+        msr_content |= MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD;
+        msr_content = (uint32_t)msr_content;
+        wrmsrl(MSR_IA32_APICBASE, msr_content);
+    }
+
+    restore_IO_APIC_setup(ioapic_entries);
+    unmask_8259A();
+
+out:
+    if ( ioapic_entries )
+        free_ioapic_entries(ioapic_entries);
+}
+
 void __devinit setup_local_APIC(void)
 {
     unsigned long oldvalue, value, ver, maxlvt;
@@ -727,7 +771,7 @@ int lapic_resume(void)
             msr_content | MSR_IA32_APICBASE_ENABLE | mp_lapic_addr);
     }
     else
-        enable_x2apic();
+        resume_x2apic();
 
     apic_write(APIC_LVTERR, ERROR_APIC_VECTOR | APIC_LVT_MASKED);
     apic_write(APIC_ID, apic_pm_state.apic_id);
@@ -894,46 +938,154 @@ no_apic:
     return -1;
 }
 
-void enable_x2apic(void)
+void check_x2apic_preenabled(void)
 {
     uint64_t msr_content;
 
-    if ( smp_processor_id() == 0 )
+    if ( !x2apic_is_available() )
+        return;
+
+    rdmsrl(MSR_IA32_APICBASE, msr_content);
+    if ( msr_content & MSR_IA32_APICBASE_EXTD )
+    {
+        printk("x2APIC mode is already enabled by BIOS.\n");
+        x2apic_preenabled = 1;
+        x2apic_enabled = 1;
+    }
+}
+
+static void enable_bsp_x2apic(void)
+{
+    struct IO_APIC_route_entry **ioapic_entries = NULL;
+    const struct genapic *x2apic_genapic = NULL;
+
+    ASSERT(smp_processor_id() == 0);
+
+    if ( x2apic_preenabled )
     {
-        if ( !iommu_supports_eim() )
+        /*
+         * Interrupt remapping should be also enabled by BIOS when
+         * x2APIC is already enabled by BIOS, otherwise it's a BIOS
+         * bug
+         */
+        if ( !intremap_enabled() )
+            panic("Interrupt remapping is not enabled by BIOS while "
+                  "x2APIC is already enabled by BIOS!\n");
+    }
+
+    x2apic_genapic = apic_x2apic_probe();
+    if ( x2apic_genapic )
+        genapic = x2apic_genapic;
+    else
+    {
+        if ( x2apic_cmdline_disable() )
         {
-            printk("x2APIC would not be enabled without EIM.\n");
-            return;
+            if ( x2apic_preenabled )
+            {
+                /* Ignore x2apic=0, and set default x2apic mode */
+                genapic = &apic_x2apic_cluster;
+                printk("x2APIC: already enabled by BIOS, ignore x2apic=0.\n");
+            }
+            else
+            {
+                printk("Not enable x2APIC due to x2apic=0 is set.\n");
+                return;
+            }
         }
-
-        if ( apic_x2apic_phys.probe() )
-            genapic = &apic_x2apic_phys;
-        else if ( apic_x2apic_cluster.probe() )
-            genapic = &apic_x2apic_cluster;
         else
         {
-            printk("x2APIC would not be enabled due to x2apic=off.\n");
-            return;
+            if ( !iommu_enabled || !iommu_intremap || !iommu_qinval )
+                panic("Cannot enable x2APIC due to iommu or interrupt "
+                      "remapping or queued invalidation is disabled "
+                      "by command line!\n");
+            else
+            {
+                if ( x2apic_preenabled )
+                    panic("x2APIC: already enabled by BIOS, but "
+                          "iommu_supports_eim fails\n");
+                else
+                {
+                    printk("Not enable x2APIC due to "
+                           "iommu_supports_eim fails!\n");
+                    return;
+                }
+            }
         }
+    }
 
-        x2apic_enabled = 1;
-        printk("Switched to APIC driver %s.\n", genapic->name);
+    ioapic_entries = alloc_ioapic_entries();
+    if ( !ioapic_entries )
+    {
+        printk("Allocate ioapic_entries failed\n");
+        goto out;
     }
-    else
+
+    if ( save_IO_APIC_setup(ioapic_entries) )
     {
-        BUG_ON(!x2apic_enabled); /* APs only enable x2apic when BSP did so. */
+        printk("Saving IO-APIC state failed\n");
+        goto out;
     }
 
+    mask_8259A();
+    mask_IO_APIC_setup(ioapic_entries);
+
+    if ( iommu_enable_IR() )
+    {
+        printk("Would not enable x2APIC due to interrupt remapping "
+               "cannot be enabled.\n");
+        goto restore_out;
+    }
+
+    x2apic_enabled = 1;
+    printk("Switched to APIC driver %s.\n", genapic->name);
+
+    if ( !x2apic_preenabled )
+    {
+        uint64_t msr_content;
+        rdmsrl(MSR_IA32_APICBASE, msr_content);
+        if ( !(msr_content & MSR_IA32_APICBASE_EXTD) )
+        {
+            msr_content |= MSR_IA32_APICBASE_ENABLE |
+                           MSR_IA32_APICBASE_EXTD;
+            msr_content = (uint32_t)msr_content;
+            wrmsrl(MSR_IA32_APICBASE, msr_content);
+            printk("x2APIC mode enabled.\n");
+        }
+    }
+
+restore_out:
+    restore_IO_APIC_setup(ioapic_entries);
+    unmask_8259A();
+
+out:
+    if ( ioapic_entries )
+        free_ioapic_entries(ioapic_entries);
+}
+
+static void enable_ap_x2apic(void)
+{
+    uint64_t msr_content;
+
+    ASSERT(smp_processor_id() != 0);
+
+    /* APs only enable x2apic when BSP did so. */
+    BUG_ON(!x2apic_enabled);
+
     rdmsrl(MSR_IA32_APICBASE, msr_content);
     if ( !(msr_content & MSR_IA32_APICBASE_EXTD) )
     {
         msr_content |= MSR_IA32_APICBASE_ENABLE | MSR_IA32_APICBASE_EXTD;
         msr_content = (uint32_t)msr_content;
         wrmsrl(MSR_IA32_APICBASE, msr_content);
-        printk("x2APIC mode enabled.\n");
     }
+}
+
+void enable_x2apic(void)
+{
+    if ( smp_processor_id() == 0 )
+        enable_bsp_x2apic();
     else
-        printk("x2APIC mode enabled by BIOS.\n");
+        enable_ap_x2apic();
 }
 
 void __init init_apic_mappings(void)