KVM: s390: Add FAULT_FLAG_RETRY_NOWAIT for guest fault

[linux-drm-fsl-dcu.git] / arch / s390 / mm / fault.c

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index d95265b2719f8e7fb0b15305b49a52130069aebd..88cef505453bfb14aa21fabb745dcd781906ee5e 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -50,6 +50,7 @@
 #define VM_FAULT_BADMAP                0x020000
 #define VM_FAULT_BADACCESS     0x040000
 #define VM_FAULT_SIGNAL                0x080000
+#define VM_FAULT_PFAULT                0x100000
 
 static unsigned long store_indication __read_mostly;
 
@@ -227,6 +228,7 @@ static noinline void do_fault_error(struct pt_regs *regs, int fault)
                        return;
                }
        case VM_FAULT_BADCONTEXT:
+       case VM_FAULT_PFAULT:
                do_no_context(regs);
                break;
        case VM_FAULT_SIGNAL:
@@ -264,6 +266,9 @@ static noinline void do_fault_error(struct pt_regs *regs, int fault)
  */
 static inline int do_exception(struct pt_regs *regs, int access)
 {
+#ifdef CONFIG_PGSTE
+       struct gmap *gmap;
+#endif
        struct task_struct *tsk;
        struct mm_struct *mm;
        struct vm_area_struct *vma;
@@ -304,9 +309,10 @@ static inline int do_exception(struct pt_regs *regs, int access)
        down_read(&mm->mmap_sem);
 
 #ifdef CONFIG_PGSTE
-       if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
-               address = __gmap_fault(address,
-                                    (struct gmap *) S390_lowcore.gmap);
+       gmap = (struct gmap *)
+               ((current->flags & PF_VCPU) ? S390_lowcore.gmap : 0);
+       if (gmap) {
+               address = __gmap_fault(address, gmap);
                if (address == -EFAULT) {
                        fault = VM_FAULT_BADMAP;
                        goto out_up;
@@ -315,6 +321,8 @@ static inline int do_exception(struct pt_regs *regs, int access)
                        fault = VM_FAULT_OOM;
                        goto out_up;
                }
+               if (gmap->pfault_enabled)
+                       flags |= FAULT_FLAG_RETRY_NOWAIT;
        }
 #endif
 
@@ -371,9 +379,19 @@ retry:
                                      regs, address);
                }
                if (fault & VM_FAULT_RETRY) {
+#ifdef CONFIG_PGSTE
+                       if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
+                               /* FAULT_FLAG_RETRY_NOWAIT has been set,
+                                * mmap_sem has not been released */
+                               current->thread.gmap_pfault = 1;
+                               fault = VM_FAULT_PFAULT;
+                               goto out_up;
+                       }
+#endif
                        /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
                         * of starvation. */
-                       flags &= ~FAULT_FLAG_ALLOW_RETRY;
+                       flags &= ~(FAULT_FLAG_ALLOW_RETRY |
+                                  FAULT_FLAG_RETRY_NOWAIT);
                        flags |= FAULT_FLAG_TRIED;
                        down_read(&mm->mmap_sem);
                        goto retry;