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 static bool kvm_pending_external_abort(struct kvm_vcpu *vcpu) 76 { 77 if (!vcpu_get_flag(vcpu, PENDING_EXCEPTION)) 78 return false; 79 80 if (vcpu_el1_is_32bit(vcpu)) { 81 switch (vcpu_get_flag(vcpu, EXCEPT_MASK)) { 82 case unpack_vcpu_flag(EXCEPT_AA32_UND): 83 case unpack_vcpu_flag(EXCEPT_AA32_IABT): 84 case unpack_vcpu_flag(EXCEPT_AA32_DABT): 85 return true; 86 default: 87 return false; 88 } 89 } else { 90 switch (vcpu_get_flag(vcpu, EXCEPT_MASK)) { 91 case unpack_vcpu_flag(EXCEPT_AA64_EL1_SYNC): 92 case unpack_vcpu_flag(EXCEPT_AA64_EL2_SYNC): 93 case unpack_vcpu_flag(EXCEPT_AA64_EL1_SERR): 94 case unpack_vcpu_flag(EXCEPT_AA64_EL2_SERR): 95 return true; 96 default: 97 return false; 98 } 99 } 100 } 101 102 /** 103 * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation 104 * or in-kernel IO emulation 105 * 106 * @vcpu: The VCPU pointer 107 */ 108 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu) 109 { 110 unsigned long data; 111 unsigned int len; 112 int mask; 113 114 /* 115 * Detect if the MMIO return was already handled or if userspace aborted 116 * the MMIO access. 117 */ 118 if (unlikely(!vcpu->mmio_needed || kvm_pending_external_abort(vcpu))) 119 return 1; 120 121 vcpu->mmio_needed = 0; 122 123 if (!kvm_vcpu_dabt_iswrite(vcpu)) { 124 struct kvm_run *run = vcpu->run; 125 126 len = kvm_vcpu_dabt_get_as(vcpu); 127 data = kvm_mmio_read_buf(run->mmio.data, len); 128 129 if (kvm_vcpu_dabt_issext(vcpu) && 130 len < sizeof(unsigned long)) { 131 mask = 1U << ((len * 8) - 1); 132 data = (data ^ mask) - mask; 133 } 134 135 if (!kvm_vcpu_dabt_issf(vcpu)) 136 data = data & 0xffffffff; 137 138 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr, 139 &data); 140 data = vcpu_data_host_to_guest(vcpu, data, len); 141 vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data); 142 } 143 144 /* 145 * The MMIO instruction is emulated and should not be re-executed 146 * in the guest. 147 */ 148 kvm_incr_pc(vcpu); 149 150 return 1; 151 } 152 153 int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa) 154 { 155 struct kvm_run *run = vcpu->run; 156 unsigned long data; 157 unsigned long rt; 158 int ret; 159 bool is_write; 160 int len; 161 u8 data_buf[8]; 162 u64 esr; 163 164 esr = kvm_vcpu_get_esr(vcpu); 165 166 /* 167 * No valid syndrome? Ask userspace for help if it has 168 * volunteered to do so, and bail out otherwise. 169 * 170 * In the protected VM case, there isn't much userspace can do 171 * though, so directly deliver an exception to the guest. 172 */ 173 if (!kvm_vcpu_dabt_isvalid(vcpu)) { 174 trace_kvm_mmio_nisv(*vcpu_pc(vcpu), esr, 175 kvm_vcpu_get_hfar(vcpu), fault_ipa); 176 177 if (vcpu_is_protected(vcpu)) 178 return kvm_inject_sea_dabt(vcpu, kvm_vcpu_get_hfar(vcpu)); 179 180 if (test_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER, 181 &vcpu->kvm->arch.flags)) { 182 run->exit_reason = KVM_EXIT_ARM_NISV; 183 run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu); 184 run->arm_nisv.fault_ipa = fault_ipa; 185 return 0; 186 } 187 188 return -ENOSYS; 189 } 190 191 /* 192 * When (DFSC == 0b00xxxx || DFSC == 0b10101x) && DFSC != 0b0000xx 193 * ESR_EL2[12:11] describe the Load/Store Type. This allows us to 194 * punt the LD64B/ST64B/ST64BV/ST64BV0 instructions to userspace, 195 * which will have to provide a full emulation of these 4 196 * instructions. No, we don't expect this do be fast. 197 * 198 * We rely on traps being set if the corresponding features are not 199 * enabled, so if we get here, userspace has promised us to handle 200 * it already. 201 */ 202 switch (kvm_vcpu_trap_get_fault(vcpu)) { 203 case 0b000100 ... 0b001111: 204 case 0b101010 ... 0b101011: 205 if (FIELD_GET(GENMASK(12, 11), esr)) { 206 run->exit_reason = KVM_EXIT_ARM_LDST64B; 207 run->arm_nisv.esr_iss = esr & ~(u64)ESR_ELx_FSC; 208 run->arm_nisv.fault_ipa = fault_ipa; 209 return 0; 210 } 211 } 212 213 /* 214 * Prepare MMIO operation. First decode the syndrome data we get 215 * from the CPU. Then try if some in-kernel emulation feels 216 * responsible, otherwise let user space do its magic. 217 */ 218 is_write = kvm_vcpu_dabt_iswrite(vcpu); 219 len = kvm_vcpu_dabt_get_as(vcpu); 220 rt = kvm_vcpu_dabt_get_rd(vcpu); 221 222 if (is_write) { 223 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt), 224 len); 225 226 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data); 227 kvm_mmio_write_buf(data_buf, len, data); 228 229 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len, 230 data_buf); 231 } else { 232 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len, 233 fault_ipa, NULL); 234 235 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len, 236 data_buf); 237 } 238 239 /* Now prepare kvm_run for the potential return to userland. */ 240 run->mmio.is_write = is_write; 241 run->mmio.phys_addr = fault_ipa; 242 run->mmio.len = len; 243 vcpu->mmio_needed = 1; 244 245 if (!ret) { 246 /* We handled the access successfully in the kernel. */ 247 if (!is_write) 248 memcpy(run->mmio.data, data_buf, len); 249 vcpu->stat.mmio_exit_kernel++; 250 kvm_handle_mmio_return(vcpu); 251 return 1; 252 } 253 254 if (is_write) 255 memcpy(run->mmio.data, data_buf, len); 256 vcpu->stat.mmio_exit_user++; 257 run->exit_reason = KVM_EXIT_MMIO; 258 return 0; 259 } 260