1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2012 - Virtual Open Systems and Columbia University 4 * Author: Christoffer Dall <c.dall@virtualopensystems.com> 5 */ 6 7 #include <linux/kvm_host.h> 8 #include <asm/kvm_emulate.h> 9 #include <trace/events/kvm.h> 10 11 #include "trace.h" 12 13 void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data) 14 { 15 void *datap = NULL; 16 union { 17 u8 byte; 18 u16 hword; 19 u32 word; 20 u64 dword; 21 } tmp; 22 23 switch (len) { 24 case 1: 25 tmp.byte = data; 26 datap = &tmp.byte; 27 break; 28 case 2: 29 tmp.hword = data; 30 datap = &tmp.hword; 31 break; 32 case 4: 33 tmp.word = data; 34 datap = &tmp.word; 35 break; 36 case 8: 37 tmp.dword = data; 38 datap = &tmp.dword; 39 break; 40 } 41 42 memcpy(buf, datap, len); 43 } 44 45 unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len) 46 { 47 unsigned long data = 0; 48 union { 49 u16 hword; 50 u32 word; 51 u64 dword; 52 } tmp; 53 54 switch (len) { 55 case 1: 56 data = *(u8 *)buf; 57 break; 58 case 2: 59 memcpy(&tmp.hword, buf, len); 60 data = tmp.hword; 61 break; 62 case 4: 63 memcpy(&tmp.word, buf, len); 64 data = tmp.word; 65 break; 66 case 8: 67 memcpy(&tmp.dword, buf, len); 68 data = tmp.dword; 69 break; 70 } 71 72 return data; 73 } 74 75 /** 76 * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation 77 * or in-kernel IO emulation 78 * 79 * @vcpu: The VCPU pointer 80 */ 81 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu) 82 { 83 unsigned long data; 84 unsigned int len; 85 int mask; 86 87 /* Detect an already handled MMIO return */ 88 if (unlikely(!vcpu->mmio_needed)) 89 return 0; 90 91 vcpu->mmio_needed = 0; 92 93 if (!kvm_vcpu_dabt_iswrite(vcpu)) { 94 struct kvm_run *run = vcpu->run; 95 96 len = kvm_vcpu_dabt_get_as(vcpu); 97 data = kvm_mmio_read_buf(run->mmio.data, len); 98 99 if (kvm_vcpu_dabt_issext(vcpu) && 100 len < sizeof(unsigned long)) { 101 mask = 1U << ((len * 8) - 1); 102 data = (data ^ mask) - mask; 103 } 104 105 if (!kvm_vcpu_dabt_issf(vcpu)) 106 data = data & 0xffffffff; 107 108 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr, 109 &data); 110 data = vcpu_data_host_to_guest(vcpu, data, len); 111 vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data); 112 } 113 114 /* 115 * The MMIO instruction is emulated and should not be re-executed 116 * in the guest. 117 */ 118 kvm_incr_pc(vcpu); 119 120 return 0; 121 } 122 123 int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa) 124 { 125 struct kvm_run *run = vcpu->run; 126 unsigned long data; 127 unsigned long rt; 128 int ret; 129 bool is_write; 130 int len; 131 u8 data_buf[8]; 132 133 /* 134 * No valid syndrome? Ask userspace for help if it has 135 * volunteered to do so, and bail out otherwise. 136 */ 137 if (!kvm_vcpu_dabt_isvalid(vcpu)) { 138 if (test_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER, 139 &vcpu->kvm->arch.flags)) { 140 run->exit_reason = KVM_EXIT_ARM_NISV; 141 run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu); 142 run->arm_nisv.fault_ipa = fault_ipa; 143 return 0; 144 } 145 146 kvm_pr_unimpl("Data abort outside memslots with no valid syndrome info\n"); 147 return -ENOSYS; 148 } 149 150 /* 151 * Prepare MMIO operation. First decode the syndrome data we get 152 * from the CPU. Then try if some in-kernel emulation feels 153 * responsible, otherwise let user space do its magic. 154 */ 155 is_write = kvm_vcpu_dabt_iswrite(vcpu); 156 len = kvm_vcpu_dabt_get_as(vcpu); 157 rt = kvm_vcpu_dabt_get_rd(vcpu); 158 159 if (is_write) { 160 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt), 161 len); 162 163 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data); 164 kvm_mmio_write_buf(data_buf, len, data); 165 166 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len, 167 data_buf); 168 } else { 169 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len, 170 fault_ipa, NULL); 171 172 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len, 173 data_buf); 174 } 175 176 /* Now prepare kvm_run for the potential return to userland. */ 177 run->mmio.is_write = is_write; 178 run->mmio.phys_addr = fault_ipa; 179 run->mmio.len = len; 180 vcpu->mmio_needed = 1; 181 182 if (!ret) { 183 /* We handled the access successfully in the kernel. */ 184 if (!is_write) 185 memcpy(run->mmio.data, data_buf, len); 186 vcpu->stat.mmio_exit_kernel++; 187 kvm_handle_mmio_return(vcpu); 188 return 1; 189 } 190 191 if (is_write) 192 memcpy(run->mmio.data, data_buf, len); 193 vcpu->stat.mmio_exit_user++; 194 run->exit_reason = KVM_EXIT_MMIO; 195 return 0; 196 } 197