x86/iopl/64: Properly context-switch IOPL on Xen PV

[pandora-kernel.git] / arch / x86 / kernel / process_64.c

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index aaab32e..557eb37 100644 (file)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -38,6 +38,7 @@
 #include <linux/io.h>
 #include <linux/ftrace.h>
 #include <linux/cpuidle.h>
+#include <xen/xen.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -52,6 +53,7 @@
 #include <asm/syscalls.h>
 #include <asm/debugreg.h>
 #include <asm/nmi.h>
+#include <asm/xen/hypervisor.h>
 
 asmlinkage extern void ret_from_fork(void);
 
@@ -221,7 +223,7 @@ void release_thread(struct task_struct *dead_task)
                if (dead_task->mm->context.ldt) {
                        printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
                                        dead_task->comm,
-                                       dead_task->mm->context.ldt,
+                                       dead_task->mm->context.ldt->entries,
                                        dead_task->mm->context.ldt->size);
                        BUG();
                }
@@ -518,6 +520,16 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
                     task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
                __switch_to_xtra(prev_p, next_p, tss);
 
+#ifdef CONFIG_XEN
+       /*
+        * On Xen PV, IOPL bits in pt_regs->flags have no effect, and
+        * current_pt_regs()->flags may not match the current task's
+        * intended IOPL.  We need to switch it manually.
+        */
+       if (unlikely(xen_pv_domain() && prev->iopl != next->iopl))
+               xen_set_iopl_mask(next->iopl);
+#endif
+
        return prev_p;
 }