commit d3ed1ceeace311af9973d17a07a114bfaf0ca1b1
author Martin Schwidefsky <schwidefsky@de.ibm.com> Tue Mar 08 11:53:35 2016 +0100
committer Christian Borntraeger <borntraeger@de.ibm.com> Fri Jun 10 12:07:27 2016 +0200
tree 1e9a353c769d89bf8eee9489f931869dcaf0651a
parent c427c42cd612719e8fb8b5891cc9761e7770024e

s390/mm: set and get guest storage key mmap locking

Move the mmap semaphore locking out of set_guest_storage_key
and get_guest_storage_key. This makes the two functions more
like the other ptep_xxx operations and allows to avoid repeated
semaphore operations if multiple keys are read or written.

Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/priv.c

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 95916fa..c6deed7 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -728,9 +728,12 @@
 
 			if (rc)
 				return rc;
-			if (set_guest_storage_key(current->mm, useraddr,
+			down_read(&current->mm->mmap_sem);
+			rc = set_guest_storage_key(current->mm, useraddr,
 					vcpu->run->s.regs.gprs[reg1] & PFMF_KEY,
-					vcpu->run->s.regs.gprs[reg1] & PFMF_NQ))
+					vcpu->run->s.regs.gprs[reg1] & PFMF_NQ);
+			up_read(&current->mm->mmap_sem);
+			if (rc)
 				return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 		}