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>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c1fcb7a3c125332aaa6daaa52ac8b72b78b1b4d0..0d7fc66289a0adb6624338eccf8b1536518ab92b 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2762,6 +2762,64 @@ register number to be used.
 The "reserved" field is meant for future extensions. It is not used by
 KVM with the currently defined set of flags.
 
+4.90 KVM_S390_GET_SKEYS
+
+Capability: KVM_CAP_S390_SKEYS
+Architectures: s390
+Type: vm ioctl
+Parameters: struct kvm_s390_skeys
+Returns: 0 on success, KVM_S390_GET_KEYS_NONE if guest is not using storage
+         keys, negative value on error
+
+This ioctl is used to get guest storage key values on the s390
+architecture. The ioctl takes parameters via the kvm_s390_skeys struct.
+
+struct kvm_s390_skeys {
+       __u64 start_gfn;
+       __u64 count;
+       __u64 skeydata_addr;
+       __u32 flags;
+       __u32 reserved[9];
+};
+
+The start_gfn field is the number of the first guest frame whose storage keys
+you want to get.
+
+The count field is the number of consecutive frames (starting from start_gfn)
+whose storage keys to get. The count field must be at least 1 and the maximum
+allowed value is defined as KVM_S390_SKEYS_ALLOC_MAX. Values outside this range
+will cause the ioctl to return -EINVAL.
+
+The skeydata_addr field is the address to a buffer large enough to hold count
+bytes. This buffer will be filled with storage key data by the ioctl.
+
+4.91 KVM_S390_SET_SKEYS
+
+Capability: KVM_CAP_S390_SKEYS
+Architectures: s390
+Type: vm ioctl
+Parameters: struct kvm_s390_skeys
+Returns: 0 on success, negative value on error
+
+This ioctl is used to set guest storage key values on the s390
+architecture. The ioctl takes parameters via the kvm_s390_skeys struct.
+See section on KVM_S390_GET_SKEYS for struct definition.
+
+The start_gfn field is the number of the first guest frame whose storage keys
+you want to set.
+
+The count field is the number of consecutive frames (starting from start_gfn)
+whose storage keys to get. The count field must be at least 1 and the maximum
+allowed value is defined as KVM_S390_SKEYS_ALLOC_MAX. Values outside this range
+will cause the ioctl to return -EINVAL.
+
+The skeydata_addr field is the address to a buffer containing count bytes of
+storage keys. Each byte in the buffer will be set as the storage key for a
+single frame starting at start_gfn for count frames.
+
+Note: If any architecturally invalid key value is found in the given data then
+the ioctl will return -EINVAL.
+
 5. The kvm_run structure
 ------------------------
 

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index fdfa10662700cbbdbe029318479a7c476d34d693..0dc22baa0a5789a2e99174f0e5404160f8f2b946 100644 (file)
--- 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;
        }

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 57445ef88097bcc0a6d91ff8f058b6807f1bed33..1162ef7a3fa1394296beae511a2221ee9dc10d5f 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -147,6 +147,16 @@ struct kvm_pit_config {
 
 #define KVM_PIT_SPEAKER_DUMMY     1
 
+struct kvm_s390_skeys {
+       __u64 start_gfn;
+       __u64 count;
+       __u64 skeydata_addr;
+       __u32 flags;
+       __u32 reserved[9];
+};
+#define KVM_S390_GET_SKEYS_NONE   1
+#define KVM_S390_SKEYS_MAX        1048576
+
 #define KVM_EXIT_UNKNOWN          0
 #define KVM_EXIT_EXCEPTION        1
 #define KVM_EXIT_IO               2
@@ -791,6 +801,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_S390_VECTOR_REGISTERS 107
 #define KVM_CAP_S390_MEM_OP 108
 #define KVM_CAP_S390_USER_STSI 109
+#define KVM_CAP_S390_SKEYS 110
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -1168,6 +1179,9 @@ struct kvm_s390_ucas_mapping {
 #define KVM_GET_REG_LIST         _IOWR(KVMIO, 0xb0, struct kvm_reg_list)
 /* Available with KVM_CAP_S390_MEM_OP */
 #define KVM_S390_MEM_OP                  _IOW(KVMIO,  0xb1, struct kvm_s390_mem_op)
+/* Available with KVM_CAP_S390_SKEYS */
+#define KVM_S390_GET_SKEYS      _IOW(KVMIO, 0xb2, struct kvm_s390_skeys)
+#define KVM_S390_SET_SKEYS      _IOW(KVMIO, 0xb3, struct kvm_s390_skeys)
 
 #define KVM_DEV_ASSIGN_ENABLE_IOMMU    (1 << 0)
 #define KVM_DEV_ASSIGN_PCI_2_3         (1 << 1)