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>

2 files changed, 21 insertions, 12 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 9d0e4d0487f4..d0156d7969e0 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1050,26 +1050,30 @@ static long kvm_s390_get_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
         if (!keys)
                 return -ENOMEM;
 
+        down_read(&current->mm->mmap_sem);
         for (i = 0; i < args->count; i++) {
                 hva = gfn_to_hva(kvm, args->start_gfn + i);
                 if (kvm_is_error_hva(hva)) {
                         r = -EFAULT;
-                        goto out;
+                        break;
                 }
 
                 curkey = get_guest_storage_key(current->mm, hva);
                 if (IS_ERR_VALUE(curkey)) {
                         r = curkey;
-                        goto out;
+                        break;
                 }
                 keys[i] = curkey;
         }
+        up_read(&current->mm->mmap_sem);
+
+        if (!r) {
+                r = copy_to_user((uint8_t __user *)args->skeydata_addr, keys,
+                                 sizeof(uint8_t) * args->count);
+                if (r)
+                        r = -EFAULT;
+        }
 
-        r = copy_to_user((uint8_t __user *)args->skeydata_addr, keys,
-                         sizeof(uint8_t) * args->count);
-        if (r)
-                r = -EFAULT;
-out:
         kvfree(keys);
         return r;
 }
@@ -1106,24 +1110,26 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
         if (r)
                 goto out;
 
+        down_read(&current->mm->mmap_sem);
         for (i = 0; i < args->count; i++) {
                 hva = gfn_to_hva(kvm, args->start_gfn + i);
                 if (kvm_is_error_hva(hva)) {
                         r = -EFAULT;
-                        goto out;
+                        break;
                 }
 
                 /* Lowest order bit is reserved */
                 if (keys[i] & 0x01) {
                         r = -EINVAL;
-                        goto out;
+                        break;
                 }
 
                 r = set_guest_storage_key(current->mm, hva,
                                           (unsigned long)keys[i], 0);
                 if (r)
-                        goto out;
+                        break;
         }
+        up_read(&current->mm->mmap_sem);
 out:
         kvfree(keys);
         return r;
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 95916fa7c670..c6deed782c61 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -728,9 +728,12 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
 
                         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);
                 }