1 files changed, 57 insertions, 8 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index f09e8c36ee80..0a1700a2be9c 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -20,6 +20,7 @@
 #include <linux/delay.h>
 #include <linux/start_kernel.h>
 #include <linux/sched.h>
+#include <linux/kprobes.h>
 #include <linux/bootmem.h>
 #include <linux/module.h>
 #include <linux/mm.h>
@@ -44,6 +45,7 @@
 #include <asm/processor.h>
 #include <asm/proto.h>
 #include <asm/msr-index.h>
+#include <asm/traps.h>
 #include <asm/setup.h>
 #include <asm/desc.h>
 #include <asm/pgtable.h>
@@ -240,10 +242,10 @@ static unsigned long xen_get_debugreg(int reg)
         return HYPERVISOR_get_debugreg(reg);
 }
 
-void xen_leave_lazy(void)
+static void xen_end_context_switch(struct task_struct *next)
 {
-        paravirt_leave_lazy(paravirt_get_lazy_mode());
         xen_mc_flush();
+        paravirt_end_context_switch(next);
 }
 
 static unsigned long xen_store_tr(void)
@@ -428,11 +430,44 @@ static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
 static int cvt_gate_to_trap(int vector, const gate_desc *val,
                             struct trap_info *info)
 {
+        unsigned long addr;
+
         if (val->type != GATE_TRAP && val->type != GATE_INTERRUPT)
                 return 0;
 
         info->vector = vector;
-        info->address = gate_offset(*val);
+
+        addr = gate_offset(*val);
+#ifdef CONFIG_X86_64
+        /*
+         * Look for known traps using IST, and substitute them
+         * appropriately.  The debugger ones are the only ones we care
+         * about.  Xen will handle faults like double_fault and
+         * machine_check, so we should never see them.  Warn if
+         * there's an unexpected IST-using fault handler.
+         */
+        if (addr == (unsigned long)debug)
+                addr = (unsigned long)xen_debug;
+        else if (addr == (unsigned long)int3)
+                addr = (unsigned long)xen_int3;
+        else if (addr == (unsigned long)stack_segment)
+                addr = (unsigned long)xen_stack_segment;
+        else if (addr == (unsigned long)double_fault ||
+                 addr == (unsigned long)nmi) {
+                /* Don't need to handle these */
+                return 0;
+#ifdef CONFIG_X86_MCE
+        } else if (addr == (unsigned long)machine_check) {
+                return 0;
+#endif
+        } else {
+                /* Some other trap using IST? */
+                if (WARN_ON(val->ist != 0))
+                        return 0;
+        }
+#endif  /* CONFIG_X86_64 */
+        info->address = addr;
+
         info->cs = gate_segment(*val);
         info->flags = val->dpl;
         /* interrupt gates clear IF */
@@ -623,10 +658,26 @@ static void xen_clts(void)
         xen_mc_issue(PARAVIRT_LAZY_CPU);
 }
 
+static DEFINE_PER_CPU(unsigned long, xen_cr0_value);
+
+static unsigned long xen_read_cr0(void)
+{
+        unsigned long cr0 = percpu_read(xen_cr0_value);
+
+        if (unlikely(cr0 == 0)) {
+                cr0 = native_read_cr0();
+                percpu_write(xen_cr0_value, cr0);
+        }
+
+        return cr0;
+}
+
 static void xen_write_cr0(unsigned long cr0)
 {
         struct multicall_space mcs;
 
+        percpu_write(xen_cr0_value, cr0);
+
         /* Only pay attention to cr0.TS; everything else is
            ignored. */
         mcs = xen_mc_entry(0);
@@ -812,7 +863,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
 
         .clts = xen_clts,
 
-        .read_cr0 = native_read_cr0,
+        .read_cr0 = xen_read_cr0,
         .write_cr0 = xen_write_cr0,
 
         .read_cr4 = native_read_cr4,
@@ -860,10 +911,8 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
         /* Xen takes care of %gs when switching to usermode for us */
         .swapgs = paravirt_nop,
 
-        .lazy_mode = {
-                .enter = paravirt_enter_lazy_cpu,
-                .leave = xen_leave_lazy,
-        },
+        .start_context_switch = paravirt_start_context_switch,
+        .end_context_switch = xen_end_context_switch,
 };
 
 static const struct pv_apic_ops xen_apic_ops __initdata = {