KEXEC: correctly revert x2apic state when kexecing

Introduce the boolean variable 'kexecing' which indicates to functions
whether we are on the kexec path or not.  This is used by
disable_local_APIC() to try and revert the APIC mode back to how it
was found on boot.

We also need some fudging of the x2apic_enabled variable.  It is used
in multiple places over the codebase to mean multiple things,
including:
    What did the user specifify on the command line?
    Did the BIOS boot me in x2apic mode?
    Is the BSP Local APIC in x2apic mode?
    What mode is my Local APIC in?

Therefore, set it up to prevent a protection fault when disabling the
IOAPICs.  (In this case, it is used in the "What mode is my Local APIC
in?" case, so the processor doesnt suffer a protection fault because
of trying to use x2apic MSRs when it should be using xapic MMIO)

Finally, make sure that interrupts are disabled when jumping into the
purgatory code.  It would be bad to service interrupts in the Xen
context when the next kernel is booting.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
index 78b35951196a4b7dda6c331ad2f5e710d37cd775..31b8c0af8433501b9813561900dd2ad44f335f45 100644 (file)
--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -37,6 +37,7 @@
 #include <asm/asm_defns.h> /* for BUILD_SMP_INTERRUPT */
 #include <mach_apic.h>
 #include <io_ports.h>
+#include <xen/kexec.h>
 
 static bool_t tdt_enabled __read_mostly;
 static bool_t tdt_enable __initdata = 1;
@@ -349,6 +350,33 @@ void disable_local_APIC(void)
         wrmsrl(MSR_IA32_APICBASE, msr_content &
                ~(MSR_IA32_APICBASE_ENABLE|MSR_IA32_APICBASE_EXTD));
     }
+
+    if ( kexecing )
+    {
+        uint64_t msr_content;
+        rdmsrl(MSR_IA32_APICBASE, msr_content);
+        msr_content &= ~(MSR_IA32_APICBASE_ENABLE|MSR_IA32_APICBASE_EXTD);
+        wrmsrl(MSR_IA32_APICBASE, msr_content);
+
+        switch ( apic_boot_mode )
+        {
+        case APIC_MODE_DISABLED:
+            break; /* Nothing to do - we did this above */
+        case APIC_MODE_XAPIC:
+            msr_content |= MSR_IA32_APICBASE_ENABLE;
+            wrmsrl(MSR_IA32_APICBASE, msr_content);
+            break;
+        case APIC_MODE_X2APIC:
+            msr_content |= (MSR_IA32_APICBASE_ENABLE|MSR_IA32_APICBASE_EXTD);
+            wrmsrl(MSR_IA32_APICBASE, msr_content);
+            break;
+        default:
+            printk("Default case when reverting #%d lapic to boot state\n",
+                   smp_processor_id());
+            break;
+        }
+    }
+
 }
 
 /*

diff --git a/xen/arch/x86/crash.c b/xen/arch/x86/crash.c
index 19508550df285dba8a19a5bf5df07fdd0ba4fbda..ab18abb4d177e99ca05c54e5497f1ab0f86514eb 100644 (file)
--- a/xen/arch/x86/crash.c
+++ b/xen/arch/x86/crash.c
@@ -27,6 +27,7 @@
 #include <asm/hvm/support.h>
 #include <asm/apic.h>
 #include <asm/io_apic.h>
+#include <xen/iommu.h>
 
 static atomic_t waiting_for_crash_ipi;
 static unsigned int crashing_cpu;
@@ -82,6 +83,12 @@ static void nmi_shootdown_cpus(void)
     iommu_crash_shutdown();
 
     __stop_this_cpu();
+
+    /* This is a bit of a hack due to the problems with the x2apic_enabled
+     * variable, but we can't do any better without a significant refactoring
+     * of the APIC code */
+    x2apic_enabled = (current_local_apic_mode() == APIC_MODE_X2APIC);
+
     disable_IO_APIC();
 }
 

diff --git a/xen/arch/x86/machine_kexec.c b/xen/arch/x86/machine_kexec.c
index d24ad217836c71aa2d2a44c2b688cc51754633c2..b6fb5d9f605b20ee66c980a2353b40a53d9e5953 100644 (file)
--- a/xen/arch/x86/machine_kexec.c
+++ b/xen/arch/x86/machine_kexec.c
@@ -88,6 +88,11 @@ void machine_kexec(xen_kexec_image_t *image)
     if ( hpet_broadcast_is_available() )
         hpet_disable_legacy_broadcast();
 
+    /* We are about to permenantly jump out of the Xen context into the kexec
+     * purgatory code.  We really dont want to be still servicing interupts.
+     */
+    local_irq_disable();
+
     /*
      * compat_machine_kexec() returns to idle pagetables, which requires us
      * to be running on a static GDT mapping (idle pagetables have no GDT

diff --git a/xen/common/kexec.c b/xen/common/kexec.c
index f889e5bb22c3bb5877e617ac598d43c098269362..bddf23c535e8438b1d528564334a501426793c72 100644 (file)
--- a/xen/common/kexec.c
+++ b/xen/common/kexec.c
@@ -29,6 +29,8 @@
 #include <compat/kexec.h>
 #endif
 
+bool_t kexecing = FALSE;
+
 static DEFINE_PER_CPU_READ_MOSTLY(void *, crash_notes);
 
 static Elf_Note *xen_crash_note;
@@ -220,6 +222,8 @@ void kexec_crash(void)
     if ( !test_bit(KEXEC_IMAGE_CRASH_BASE + pos, &kexec_flags) )
         return;
 
+    kexecing = TRUE;
+
     kexec_common_shutdown();
     kexec_crash_save_cpu();
     machine_crash_shutdown();
@@ -232,6 +236,8 @@ static long kexec_reboot(void *_image)
 {
     xen_kexec_image_t *image = _image;
 
+    kexecing = TRUE;
+
     kexec_common_shutdown();
     machine_reboot_kexec(image);
 

diff --git a/xen/include/xen/kexec.h b/xen/include/xen/kexec.h
index 26df1ac9ac05d218f1da1337dcaeed5761e49bfd..db58e623613db5766ae424b4ed289352d1737d39 100644 (file)
--- a/xen/include/xen/kexec.h
+++ b/xen/include/xen/kexec.h
@@ -12,6 +12,8 @@ typedef struct xen_kexec_reserve {
 
 extern xen_kexec_reserve_t kexec_crash_area;
 
+extern bool_t kexecing;
+
 void set_kexec_crash_area_size(u64 system_ram);
 
 /* We have space for 4 images to support atomic update