[Xen-devel] [PATCH 3 of 3] kexec: disable iommu jumping into the kdump kernel

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

kdump kernels are unable to boot with IOMMU enabled,
this patch disabled IOMMU mode and removes some of the generic
code from the shutdown path which doesnt work after other
CPUs have been shot down.

Also, leave local interrupts disabled when jumping into pugatory
as we have no idea whats in there and really dont want to be
servicing interrupts when our entire state is invalid.

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

diff -r e80b5280fe2f -r aaf44d1a903d xen/arch/x86/crash.c
--- a/xen/arch/x86/crash.c      Wed May 18 19:00:13 2011 +0100
+++ b/xen/arch/x86/crash.c      Wed May 18 19:00:13 2011 +0100
@@ -27,6 +27,8 @@
 #include <asm/hvm/support.h>
 #include <asm/apic.h>
 #include <asm/io_apic.h>
+#include <xen/iommu.h>
+#include <asm/hvm/iommu.h>
 
 static atomic_t waiting_for_crash_ipi;
 static unsigned int crashing_cpu;
@@ -43,7 +45,10 @@ static int crash_nmi_callback(struct cpu
 
     kexec_crash_save_cpu();
 
-    __stop_this_cpu();
+    disable_local_APIC();
+    hvm_cpu_down();
+    clts();
+    asm volatile ( "fninit" );
 
     atomic_dec(&waiting_for_crash_ipi);
 
@@ -56,6 +61,7 @@ static int crash_nmi_callback(struct cpu
 static void nmi_shootdown_cpus(void)
 {
     unsigned long msecs;
+    u64 msr_contents;
 
     local_irq_disable();
 
@@ -77,18 +83,43 @@ static void nmi_shootdown_cpus(void)
         msecs--;
     }
 
-    __stop_this_cpu();
+    disable_local_APIC();
+    hvm_cpu_down();
+    clts();
+    asm volatile ( "fninit" );
+
+    /* This is a bit of a hack but there is no other way to shutdown correctly
+     * without a significant refactoring of the APIC code */
+    rdmsrl(MSR_IA32_APICBASE, msr_contents);
+    if ( cpu_has(&current_cpu_data, X86_FEATURE_X2APIC)
+         && (msr_contents & MSR_IA32_APICBASE_EXTD) )
+        x2apic_enabled = 1;
+    else
+        x2apic_enabled = 0;
+
     disable_IO_APIC();
-
-    local_irq_enable();
 }
 
 void machine_crash_shutdown(void)
 {
     crash_xen_info_t *info;
+    const struct iommu_ops * ops;
 
     nmi_shootdown_cpus();
 
+    /* Yes i know this is hacky but it is the easiest solution.  I should add 
an iommu_ops
+     * function called crash() or so which just disables the iommu 'fun' 
without saving state
+     */
+    ops = iommu_get_ops();
+    if(ops)
+        ops->suspend();
+
+    /* Yes i know this is from driver/passthrough/vtd/ but it appears to be 
architecture
+     * independant, and also bears little/no relation to x2apic.  Needs 
cleaning up
+     */
+    iommu_disable_x2apic_IR();
+
+
     info = kexec_crash_save_info();
     info->xen_phys_start = xen_phys_start;
     info->dom0_pfn_to_mfn_frame_list_list =
diff -r e80b5280fe2f -r aaf44d1a903d xen/arch/x86/hpet.c
--- a/xen/arch/x86/hpet.c       Wed May 18 19:00:13 2011 +0100
+++ b/xen/arch/x86/hpet.c       Wed May 18 19:00:13 2011 +0100
@@ -670,6 +670,33 @@ void hpet_disable_legacy_broadcast(void)
     smp_send_event_check_mask(&cpu_online_map);
 }
 
+/* This function is similar to the regular
+ * hpet_disable_legacy_broadcast function, except it is called
+ * on the crash path with only the current processor up, so we
+ * can forget the locks and really cant send an event check IPI
+ * to the other processors */
+void crash_hpet_disable_legacy_broadcast(void)
+{
+    u32 cfg;
+
+    if ( !hpet_events || !(hpet_events->flags & HPET_EVT_LEGACY) )
+        return;
+
+    hpet_events->flags |= HPET_EVT_DISABLE;
+
+    /* disable HPET T0 */
+    cfg = hpet_read32(HPET_Tn_CFG(0));
+    cfg &= ~HPET_TN_ENABLE;
+    hpet_write32(cfg, HPET_Tn_CFG(0));
+
+    /* Stop HPET legacy interrupts */
+    cfg = hpet_read32(HPET_CFG);
+    cfg &= ~HPET_CFG_LEGACY;
+    hpet_write32(cfg, HPET_CFG);
+
+}
+
+
 void hpet_broadcast_enter(void)
 {
     unsigned int cpu = smp_processor_id();
diff -r e80b5280fe2f -r aaf44d1a903d xen/arch/x86/machine_kexec.c
--- a/xen/arch/x86/machine_kexec.c      Wed May 18 19:00:13 2011 +0100
+++ b/xen/arch/x86/machine_kexec.c      Wed May 18 19:00:13 2011 +0100
@@ -97,7 +97,7 @@ void machine_kexec(xen_kexec_image_t *im
     };
 
     if ( hpet_broadcast_is_available() )
-        hpet_disable_legacy_broadcast();
+        crash_hpet_disable_legacy_broadcast();
 
     /*
      * compat_machine_kexec() returns to idle pagetables, which requires us
diff -r e80b5280fe2f -r aaf44d1a903d xen/include/asm-x86/hpet.h
--- a/xen/include/asm-x86/hpet.h        Wed May 18 19:00:13 2011 +0100
+++ b/xen/include/asm-x86/hpet.h        Wed May 18 19:00:13 2011 +0100
@@ -73,5 +73,6 @@ void hpet_broadcast_enter(void);
 void hpet_broadcast_exit(void);
 int hpet_broadcast_is_available(void);
 void hpet_disable_legacy_broadcast(void);
+void crash_hpet_disable_legacy_broadcast(void);
 
 #endif /* __X86_HPET_H__ */

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