1 | // SPDX-License-Identifier: GPL-2.0 |
2 | // Copyright (C) 2020 Arm Ltd. |
3 | |
4 | #include <linux/arm-smccc.h> |
5 | #include <linux/kvm_host.h> |
6 | |
7 | #include <asm/kvm_emulate.h> |
8 | |
9 | #include <kvm/arm_hypercalls.h> |
10 | |
11 | #define ARM_SMCCC_TRNG_VERSION_1_0 0x10000UL |
12 | |
13 | /* Those values are deliberately separate from the generic SMCCC definitions. */ |
14 | #define TRNG_SUCCESS 0UL |
15 | #define TRNG_NOT_SUPPORTED ((unsigned long)-1) |
16 | #define TRNG_INVALID_PARAMETER ((unsigned long)-2) |
17 | #define TRNG_NO_ENTROPY ((unsigned long)-3) |
18 | |
19 | #define TRNG_MAX_BITS64 192 |
20 | |
21 | static const uuid_t arm_smc_trng_uuid __aligned(4) = UUID_INIT( |
22 | 0x0d21e000, 0x4384, 0x11eb, 0x80, 0x70, 0x52, 0x44, 0x55, 0x4e, 0x5a, 0x4c); |
23 | |
24 | static int kvm_trng_do_rnd(struct kvm_vcpu *vcpu, int size) |
25 | { |
26 | DECLARE_BITMAP(bits, TRNG_MAX_BITS64); |
27 | u32 num_bits = smccc_get_arg1(vcpu); |
28 | int i; |
29 | |
30 | if (num_bits > 3 * size) { |
31 | smccc_set_retval(vcpu, TRNG_INVALID_PARAMETER, a1: 0, a2: 0, a3: 0); |
32 | return 1; |
33 | } |
34 | |
35 | /* get as many bits as we need to fulfil the request */ |
36 | for (i = 0; i < DIV_ROUND_UP(num_bits, BITS_PER_LONG); i++) |
37 | bits[i] = get_random_long(); |
38 | |
39 | bitmap_clear(map: bits, start: num_bits, TRNG_MAX_BITS64 - num_bits); |
40 | |
41 | if (size == 32) |
42 | smccc_set_retval(vcpu, TRNG_SUCCESS, lower_32_bits(bits[1]), |
43 | upper_32_bits(bits[0]), lower_32_bits(bits[0])); |
44 | else |
45 | smccc_set_retval(vcpu, TRNG_SUCCESS, a1: bits[2], a2: bits[1], a3: bits[0]); |
46 | |
47 | memzero_explicit(s: bits, count: sizeof(bits)); |
48 | return 1; |
49 | } |
50 | |
51 | int kvm_trng_call(struct kvm_vcpu *vcpu) |
52 | { |
53 | const __le32 *u = (__le32 *)arm_smc_trng_uuid.b; |
54 | u32 func_id = smccc_get_function(vcpu); |
55 | unsigned long val = TRNG_NOT_SUPPORTED; |
56 | int size = 64; |
57 | |
58 | switch (func_id) { |
59 | case ARM_SMCCC_TRNG_VERSION: |
60 | val = ARM_SMCCC_TRNG_VERSION_1_0; |
61 | break; |
62 | case ARM_SMCCC_TRNG_FEATURES: |
63 | switch (smccc_get_arg1(vcpu)) { |
64 | case ARM_SMCCC_TRNG_VERSION: |
65 | case ARM_SMCCC_TRNG_FEATURES: |
66 | case ARM_SMCCC_TRNG_GET_UUID: |
67 | case ARM_SMCCC_TRNG_RND32: |
68 | case ARM_SMCCC_TRNG_RND64: |
69 | val = TRNG_SUCCESS; |
70 | } |
71 | break; |
72 | case ARM_SMCCC_TRNG_GET_UUID: |
73 | smccc_set_retval(vcpu, le32_to_cpu(u[0]), le32_to_cpu(u[1]), |
74 | le32_to_cpu(u[2]), le32_to_cpu(u[3])); |
75 | return 1; |
76 | case ARM_SMCCC_TRNG_RND32: |
77 | size = 32; |
78 | fallthrough; |
79 | case ARM_SMCCC_TRNG_RND64: |
80 | return kvm_trng_do_rnd(vcpu, size); |
81 | } |
82 | |
83 | smccc_set_retval(vcpu, a0: val, a1: 0, a2: 0, a3: 0); |
84 | return 1; |
85 | } |
86 | |