1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun // Copyright (C) 2020 Arm Ltd.
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun #include <linux/arm-smccc.h>
5*4882a593Smuzhiyun #include <linux/kvm_host.h>
6*4882a593Smuzhiyun
7*4882a593Smuzhiyun #include <asm/kvm_emulate.h>
8*4882a593Smuzhiyun
9*4882a593Smuzhiyun #include <kvm/arm_hypercalls.h>
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun #define ARM_SMCCC_TRNG_VERSION_1_0 0x10000UL
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun /* Those values are deliberately separate from the generic SMCCC definitions. */
14*4882a593Smuzhiyun #define TRNG_SUCCESS 0UL
15*4882a593Smuzhiyun #define TRNG_NOT_SUPPORTED ((unsigned long)-1)
16*4882a593Smuzhiyun #define TRNG_INVALID_PARAMETER ((unsigned long)-2)
17*4882a593Smuzhiyun #define TRNG_NO_ENTROPY ((unsigned long)-3)
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun #define TRNG_MAX_BITS64 192
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun static const uuid_t arm_smc_trng_uuid __aligned(4) = UUID_INIT(
22*4882a593Smuzhiyun 0x0d21e000, 0x4384, 0x11eb, 0x80, 0x70, 0x52, 0x44, 0x55, 0x4e, 0x5a, 0x4c);
23*4882a593Smuzhiyun
kvm_trng_do_rnd(struct kvm_vcpu * vcpu,int size)24*4882a593Smuzhiyun static int kvm_trng_do_rnd(struct kvm_vcpu *vcpu, int size)
25*4882a593Smuzhiyun {
26*4882a593Smuzhiyun DECLARE_BITMAP(bits, TRNG_MAX_BITS64);
27*4882a593Smuzhiyun u32 num_bits = smccc_get_arg1(vcpu);
28*4882a593Smuzhiyun int i;
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun if (num_bits > 3 * size) {
31*4882a593Smuzhiyun smccc_set_retval(vcpu, TRNG_INVALID_PARAMETER, 0, 0, 0);
32*4882a593Smuzhiyun return 1;
33*4882a593Smuzhiyun }
34*4882a593Smuzhiyun
35*4882a593Smuzhiyun /* get as many bits as we need to fulfil the request */
36*4882a593Smuzhiyun for (i = 0; i < DIV_ROUND_UP(num_bits, BITS_PER_LONG); i++)
37*4882a593Smuzhiyun bits[i] = get_random_long();
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun bitmap_clear(bits, num_bits, TRNG_MAX_BITS64 - num_bits);
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun if (size == 32)
42*4882a593Smuzhiyun smccc_set_retval(vcpu, TRNG_SUCCESS, lower_32_bits(bits[1]),
43*4882a593Smuzhiyun upper_32_bits(bits[0]), lower_32_bits(bits[0]));
44*4882a593Smuzhiyun else
45*4882a593Smuzhiyun smccc_set_retval(vcpu, TRNG_SUCCESS, bits[2], bits[1], bits[0]);
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun memzero_explicit(bits, sizeof(bits));
48*4882a593Smuzhiyun return 1;
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
kvm_trng_call(struct kvm_vcpu * vcpu)51*4882a593Smuzhiyun int kvm_trng_call(struct kvm_vcpu *vcpu)
52*4882a593Smuzhiyun {
53*4882a593Smuzhiyun const __le32 *u = (__le32 *)arm_smc_trng_uuid.b;
54*4882a593Smuzhiyun u32 func_id = smccc_get_function(vcpu);
55*4882a593Smuzhiyun unsigned long val = TRNG_NOT_SUPPORTED;
56*4882a593Smuzhiyun int size = 64;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun switch (func_id) {
59*4882a593Smuzhiyun case ARM_SMCCC_TRNG_VERSION:
60*4882a593Smuzhiyun val = ARM_SMCCC_TRNG_VERSION_1_0;
61*4882a593Smuzhiyun break;
62*4882a593Smuzhiyun case ARM_SMCCC_TRNG_FEATURES:
63*4882a593Smuzhiyun switch (smccc_get_arg1(vcpu)) {
64*4882a593Smuzhiyun case ARM_SMCCC_TRNG_VERSION:
65*4882a593Smuzhiyun case ARM_SMCCC_TRNG_FEATURES:
66*4882a593Smuzhiyun case ARM_SMCCC_TRNG_GET_UUID:
67*4882a593Smuzhiyun case ARM_SMCCC_TRNG_RND32:
68*4882a593Smuzhiyun case ARM_SMCCC_TRNG_RND64:
69*4882a593Smuzhiyun val = TRNG_SUCCESS;
70*4882a593Smuzhiyun }
71*4882a593Smuzhiyun break;
72*4882a593Smuzhiyun case ARM_SMCCC_TRNG_GET_UUID:
73*4882a593Smuzhiyun smccc_set_retval(vcpu, le32_to_cpu(u[0]), le32_to_cpu(u[1]),
74*4882a593Smuzhiyun le32_to_cpu(u[2]), le32_to_cpu(u[3]));
75*4882a593Smuzhiyun return 1;
76*4882a593Smuzhiyun case ARM_SMCCC_TRNG_RND32:
77*4882a593Smuzhiyun size = 32;
78*4882a593Smuzhiyun fallthrough;
79*4882a593Smuzhiyun case ARM_SMCCC_TRNG_RND64:
80*4882a593Smuzhiyun return kvm_trng_do_rnd(vcpu, size);
81*4882a593Smuzhiyun }
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun smccc_set_retval(vcpu, val, 0, 0, 0);
84*4882a593Smuzhiyun return 1;
85*4882a593Smuzhiyun }
86