[PATCH v1 04/11] KVM: s390: pv: handle secure storage exceptions for normal guests

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

With upcoming patches, normal guests might touch secure pages.

This patch extends the existing exception handler to convert the pages
to non secure also when the exception is triggered by a normal guest.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 arch/s390/mm/fault.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index efdef35bc415..24a39457cd48 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -789,9 +789,20 @@ void do_secure_storage_access(struct pt_regs *regs)
 	struct vm_area_struct *vma;
 	struct mm_struct *mm;
 	struct page *page;
+	struct gmap *gmap;
 	int rc;
 
 	switch (get_fault_type(regs)) {
+	case GMAP_FAULT:
+		gmap = (struct gmap *)S390_lowcore.gmap;
+		/*
+		 * Very unlikely, but if it happens, simply try again.
+		 * The next attempt will trigger a different exception.
+		 */
+		addr = __gmap_translate(gmap, addr);
+		if (addr == -EFAULT)
+			break;
+		fallthrough;
 	case USER_FAULT:
 		mm = current->mm;
 		mmap_read_lock(mm);
@@ -820,7 +831,6 @@ void do_secure_storage_access(struct pt_regs *regs)
 		if (rc)
 			BUG();
 		break;
-	case GMAP_FAULT:
 	default:
 		do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
 		WARN_ON_ONCE(1);
-- 
2.31.1