KVM: s390: Create ioctl for Getting/Setting guest storage keys

Provide the KVM_S390_GET_SKEYS and KVM_S390_SET_SKEYS ioctl which can be used
to get/set guest storage keys. This functionality is needed for live migration
of s390 guests that use storage keys.

Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 123 insertions, 0 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index fdfa10662700..0dc22baa0a57 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -179,6 +179,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_MP_STATE:
 	case KVM_CAP_S390_USER_SIGP:
 	case KVM_CAP_S390_USER_STSI:
+	case KVM_CAP_S390_SKEYS:
 		r = 1;
 		break;
 	case KVM_CAP_S390_MEM_OP:
@@ -729,6 +730,108 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
 	return ret;
 }
 
+static long kvm_s390_get_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
+{
+	uint8_t *keys;
+	uint64_t hva;
+	unsigned long curkey;
+	int i, r = 0;
+
+	if (args->flags != 0)
+		return -EINVAL;
+
+	/* Is this guest using storage keys? */
+	if (!mm_use_skey(current->mm))
+		return KVM_S390_GET_SKEYS_NONE;
+
+	/* Enforce sane limit on memory allocation */
+	if (args->count < 1 || args->count > KVM_S390_SKEYS_MAX)
+		return -EINVAL;
+
+	keys = kmalloc_array(args->count, sizeof(uint8_t),
+			     GFP_KERNEL | __GFP_NOWARN);
+	if (!keys)
+		keys = vmalloc(sizeof(uint8_t) * args->count);
+	if (!keys)
+		return -ENOMEM;
+
+	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;
+		}
+
+		curkey = get_guest_storage_key(current->mm, hva);
+		if (IS_ERR_VALUE(curkey)) {
+			r = curkey;
+			goto out;
+		}
+		keys[i] = curkey;
+	}
+
+	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;
+}
+
+static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
+{
+	uint8_t *keys;
+	uint64_t hva;
+	int i, r = 0;
+
+	if (args->flags != 0)
+		return -EINVAL;
+
+	/* Enforce sane limit on memory allocation */
+	if (args->count < 1 || args->count > KVM_S390_SKEYS_MAX)
+		return -EINVAL;
+
+	keys = kmalloc_array(args->count, sizeof(uint8_t),
+			     GFP_KERNEL | __GFP_NOWARN);
+	if (!keys)
+		keys = vmalloc(sizeof(uint8_t) * args->count);
+	if (!keys)
+		return -ENOMEM;
+
+	r = copy_from_user(keys, (uint8_t __user *)args->skeydata_addr,
+			   sizeof(uint8_t) * args->count);
+	if (r) {
+		r = -EFAULT;
+		goto out;
+	}
+
+	/* Enable storage key handling for the guest */
+	s390_enable_skey();
+
+	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;
+		}
+
+		/* Lowest order bit is reserved */
+		if (keys[i] & 0x01) {
+			r = -EINVAL;
+			goto out;
+		}
+
+		r = set_guest_storage_key(current->mm, hva,
+					  (unsigned long)keys[i], 0);
+		if (r)
+			goto out;
+	}
+out:
+	kvfree(keys);
+	return r;
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
 		       unsigned int ioctl, unsigned long arg)
 {
@@ -788,6 +891,26 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		r = kvm_s390_vm_has_attr(kvm, &attr);
 		break;
 	}
+	case KVM_S390_GET_SKEYS: {
+		struct kvm_s390_skeys args;
+
+		r = -EFAULT;
+		if (copy_from_user(&args, argp,
+				   sizeof(struct kvm_s390_skeys)))
+			break;
+		r = kvm_s390_get_skeys(kvm, &args);
+		break;
+	}
+	case KVM_S390_SET_SKEYS: {
+		struct kvm_s390_skeys args;
+
+		r = -EFAULT;
+		if (copy_from_user(&args, argp,
+				   sizeof(struct kvm_s390_skeys)))
+			break;
+		r = kvm_s390_set_skeys(kvm, &args);
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}