cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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trng.c (2256B)

      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
     21static const uuid_t arm_smc_trng_uuid __aligned(4) = UUID_INIT(
     22	0x0d21e000, 0x4384, 0x11eb, 0x80, 0x70, 0x52, 0x44, 0x55, 0x4e, 0x5a, 0x4c);
     23
     24static 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
     51int 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}