KVM: s390: pv: refactor s390_reset_acc

Refactor s390_reset_acc so that it can be reused in upcoming patches.

We don't want to hold all the locks used in a walk_page_range for too
long, and the destroy page UVC does take some time to complete.
Therefore we quickly gather the pages to destroy, and then destroy them
without holding all the locks.

The new refactored function optionally allows to return early without
completing if a fatal signal is pending (and return and appropriate
error code). Two wrappers are provided to call the new function.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Link: https://lore.kernel.org/r/20220628135619.32410-5-imbrenda@linux.ibm.com
Message-Id: <20220628135619.32410-5-imbrenda@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>

1 files changed, 36 insertions, 1 deletions

diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index f4073106e1f3..5cc46e0dde62 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -147,7 +147,42 @@ int gmap_mprotect_notify(struct gmap *, unsigned long start,
 void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long dirty_bitmap[4],
 			     unsigned long gaddr, unsigned long vmaddr);
 int gmap_mark_unmergeable(void);
-void s390_reset_acc(struct mm_struct *mm);
 void s390_unlist_old_asce(struct gmap *gmap);
 int s390_replace_asce(struct gmap *gmap);
+void s390_uv_destroy_pfns(unsigned long count, unsigned long *pfns);
+int __s390_uv_destroy_range(struct mm_struct *mm, unsigned long start,
+			    unsigned long end, bool interruptible);
+
+/**
+ * s390_uv_destroy_range - Destroy a range of pages in the given mm.
+ * @mm: the mm on which to operate on
+ * @start: the start of the range
+ * @end: the end of the range
+ *
+ * This function will call cond_sched, so it should not generate stalls, but
+ * it will otherwise only return when it completed.
+ */
+static inline void s390_uv_destroy_range(struct mm_struct *mm, unsigned long start,
+					 unsigned long end)
+{
+	(void)__s390_uv_destroy_range(mm, start, end, false);
+}
+
+/**
+ * s390_uv_destroy_range_interruptible - Destroy a range of pages in the
+ * given mm, but stop when a fatal signal is received.
+ * @mm: the mm on which to operate on
+ * @start: the start of the range
+ * @end: the end of the range
+ *
+ * This function will call cond_sched, so it should not generate stalls. If
+ * a fatal signal is received, it will return with -EINTR immediately,
+ * without finishing destroying the whole range. Upon successful
+ * completion, 0 is returned.
+ */
+static inline int s390_uv_destroy_range_interruptible(struct mm_struct *mm, unsigned long start,
+						      unsigned long end)
+{
+	return __s390_uv_destroy_range(mm, start, end, true);
+}
 #endif /* _ASM_S390_GMAP_H */