1*a8e190cdSArd Biesheuvel // SPDX-License-Identifier: GPL-2.0
2*a8e190cdSArd Biesheuvel // Copyright (C) 2020 Arm Ltd.
3*a8e190cdSArd Biesheuvel
4*a8e190cdSArd Biesheuvel #include <linux/arm-smccc.h>
5*a8e190cdSArd Biesheuvel #include <linux/kvm_host.h>
6*a8e190cdSArd Biesheuvel
7*a8e190cdSArd Biesheuvel #include <asm/kvm_emulate.h>
8*a8e190cdSArd Biesheuvel
9*a8e190cdSArd Biesheuvel #include <kvm/arm_hypercalls.h>
10*a8e190cdSArd Biesheuvel
11*a8e190cdSArd Biesheuvel #define ARM_SMCCC_TRNG_VERSION_1_0 0x10000UL
12*a8e190cdSArd Biesheuvel
13*a8e190cdSArd Biesheuvel /* Those values are deliberately separate from the generic SMCCC definitions. */
14*a8e190cdSArd Biesheuvel #define TRNG_SUCCESS 0UL
15*a8e190cdSArd Biesheuvel #define TRNG_NOT_SUPPORTED ((unsigned long)-1)
16*a8e190cdSArd Biesheuvel #define TRNG_INVALID_PARAMETER ((unsigned long)-2)
17*a8e190cdSArd Biesheuvel #define TRNG_NO_ENTROPY ((unsigned long)-3)
18*a8e190cdSArd Biesheuvel
19*a8e190cdSArd Biesheuvel #define TRNG_MAX_BITS64 192
20*a8e190cdSArd Biesheuvel
21*a8e190cdSArd Biesheuvel static const uuid_t arm_smc_trng_uuid __aligned(4) = UUID_INIT(
22*a8e190cdSArd Biesheuvel 0x0d21e000, 0x4384, 0x11eb, 0x80, 0x70, 0x52, 0x44, 0x55, 0x4e, 0x5a, 0x4c);
23*a8e190cdSArd Biesheuvel
kvm_trng_do_rnd(struct kvm_vcpu * vcpu,int size)24*a8e190cdSArd Biesheuvel static int kvm_trng_do_rnd(struct kvm_vcpu *vcpu, int size)
25*a8e190cdSArd Biesheuvel {
26*a8e190cdSArd Biesheuvel DECLARE_BITMAP(bits, TRNG_MAX_BITS64);
27*a8e190cdSArd Biesheuvel u32 num_bits = smccc_get_arg1(vcpu);
28*a8e190cdSArd Biesheuvel int i;
29*a8e190cdSArd Biesheuvel
30*a8e190cdSArd Biesheuvel if (num_bits > 3 * size) {
31*a8e190cdSArd Biesheuvel smccc_set_retval(vcpu, TRNG_INVALID_PARAMETER, 0, 0, 0);
32*a8e190cdSArd Biesheuvel return 1;
33*a8e190cdSArd Biesheuvel }
34*a8e190cdSArd Biesheuvel
35*a8e190cdSArd Biesheuvel /* get as many bits as we need to fulfil the request */
36*a8e190cdSArd Biesheuvel for (i = 0; i < DIV_ROUND_UP(num_bits, BITS_PER_LONG); i++)
37*a8e190cdSArd Biesheuvel bits[i] = get_random_long();
38*a8e190cdSArd Biesheuvel
39*a8e190cdSArd Biesheuvel bitmap_clear(bits, num_bits, TRNG_MAX_BITS64 - num_bits);
40*a8e190cdSArd Biesheuvel
41*a8e190cdSArd Biesheuvel if (size == 32)
42*a8e190cdSArd Biesheuvel smccc_set_retval(vcpu, TRNG_SUCCESS, lower_32_bits(bits[1]),
43*a8e190cdSArd Biesheuvel upper_32_bits(bits[0]), lower_32_bits(bits[0]));
44*a8e190cdSArd Biesheuvel else
45*a8e190cdSArd Biesheuvel smccc_set_retval(vcpu, TRNG_SUCCESS, bits[2], bits[1], bits[0]);
46*a8e190cdSArd Biesheuvel
47*a8e190cdSArd Biesheuvel memzero_explicit(bits, sizeof(bits));
48*a8e190cdSArd Biesheuvel return 1;
49*a8e190cdSArd Biesheuvel }
50*a8e190cdSArd Biesheuvel
kvm_trng_call(struct kvm_vcpu * vcpu)51*a8e190cdSArd Biesheuvel int kvm_trng_call(struct kvm_vcpu *vcpu)
52*a8e190cdSArd Biesheuvel {
53*a8e190cdSArd Biesheuvel const __le32 *u = (__le32 *)arm_smc_trng_uuid.b;
54*a8e190cdSArd Biesheuvel u32 func_id = smccc_get_function(vcpu);
55*a8e190cdSArd Biesheuvel unsigned long val = TRNG_NOT_SUPPORTED;
56*a8e190cdSArd Biesheuvel int size = 64;
57*a8e190cdSArd Biesheuvel
58*a8e190cdSArd Biesheuvel switch (func_id) {
59*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_VERSION:
60*a8e190cdSArd Biesheuvel val = ARM_SMCCC_TRNG_VERSION_1_0;
61*a8e190cdSArd Biesheuvel break;
62*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_FEATURES:
63*a8e190cdSArd Biesheuvel switch (smccc_get_arg1(vcpu)) {
64*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_VERSION:
65*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_FEATURES:
66*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_GET_UUID:
67*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_RND32:
68*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_RND64:
69*a8e190cdSArd Biesheuvel val = TRNG_SUCCESS;
70*a8e190cdSArd Biesheuvel }
71*a8e190cdSArd Biesheuvel break;
72*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_GET_UUID:
73*a8e190cdSArd Biesheuvel smccc_set_retval(vcpu, le32_to_cpu(u[0]), le32_to_cpu(u[1]),
74*a8e190cdSArd Biesheuvel le32_to_cpu(u[2]), le32_to_cpu(u[3]));
75*a8e190cdSArd Biesheuvel return 1;
76*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_RND32:
77*a8e190cdSArd Biesheuvel size = 32;
78*a8e190cdSArd Biesheuvel fallthrough;
79*a8e190cdSArd Biesheuvel case ARM_SMCCC_TRNG_RND64:
80*a8e190cdSArd Biesheuvel return kvm_trng_do_rnd(vcpu, size);
81*a8e190cdSArd Biesheuvel }
82*a8e190cdSArd Biesheuvel
83*a8e190cdSArd Biesheuvel smccc_set_retval(vcpu, val, 0, 0, 0);
84*a8e190cdSArd Biesheuvel return 1;
85*a8e190cdSArd Biesheuvel }
86