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, 0, 0, 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(bits, 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, bits[2], bits[1], bits[0]); 46 47 memzero_explicit(bits, 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, val, 0, 0, 0); 84 return 1; 85 } 86