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 * @run: The VCPU run struct containing the mmio data 81 */ 82 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) 83 { 84 unsigned long data; 85 unsigned int len; 86 int mask; 87 88 /* Detect an already handled MMIO return */ 89 if (unlikely(!vcpu->mmio_needed)) 90 return 0; 91 92 vcpu->mmio_needed = 0; 93 94 if (!kvm_vcpu_dabt_iswrite(vcpu)) { 95 len = kvm_vcpu_dabt_get_as(vcpu); 96 data = kvm_mmio_read_buf(run->mmio.data, len); 97 98 if (kvm_vcpu_dabt_issext(vcpu) && 99 len < sizeof(unsigned long)) { 100 mask = 1U << ((len * 8) - 1); 101 data = (data ^ mask) - mask; 102 } 103 104 if (!kvm_vcpu_dabt_issf(vcpu)) 105 data = data & 0xffffffff; 106 107 trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr, 108 &data); 109 data = vcpu_data_host_to_guest(vcpu, data, len); 110 vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data); 111 } 112 113 /* 114 * The MMIO instruction is emulated and should not be re-executed 115 * in the guest. 116 */ 117 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); 118 119 return 0; 120 } 121 122 int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, 123 phys_addr_t fault_ipa) 124 { 125 unsigned long data; 126 unsigned long rt; 127 int ret; 128 bool is_write; 129 int len; 130 u8 data_buf[8]; 131 132 /* 133 * No valid syndrome? Ask userspace for help if it has 134 * volunteered to do so, and bail out otherwise. 135 */ 136 if (!kvm_vcpu_dabt_isvalid(vcpu)) { 137 if (vcpu->kvm->arch.return_nisv_io_abort_to_user) { 138 run->exit_reason = KVM_EXIT_ARM_NISV; 139 run->arm_nisv.esr_iss = kvm_vcpu_dabt_iss_nisv_sanitized(vcpu); 140 run->arm_nisv.fault_ipa = fault_ipa; 141 return 0; 142 } 143 144 kvm_pr_unimpl("Data abort outside memslots with no valid syndrome info\n"); 145 return -ENOSYS; 146 } 147 148 /* Page table accesses IO mem: tell guest to fix its TTBR */ 149 if (kvm_vcpu_dabt_iss1tw(vcpu)) { 150 kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu)); 151 return 1; 152 } 153 154 /* 155 * Prepare MMIO operation. First decode the syndrome data we get 156 * from the CPU. Then try if some in-kernel emulation feels 157 * responsible, otherwise let user space do its magic. 158 */ 159 is_write = kvm_vcpu_dabt_iswrite(vcpu); 160 len = kvm_vcpu_dabt_get_as(vcpu); 161 rt = kvm_vcpu_dabt_get_rd(vcpu); 162 163 if (is_write) { 164 data = vcpu_data_guest_to_host(vcpu, vcpu_get_reg(vcpu, rt), 165 len); 166 167 trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, len, fault_ipa, &data); 168 kvm_mmio_write_buf(data_buf, len, data); 169 170 ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, fault_ipa, len, 171 data_buf); 172 } else { 173 trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, len, 174 fault_ipa, NULL); 175 176 ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_ipa, len, 177 data_buf); 178 } 179 180 /* Now prepare kvm_run for the potential return to userland. */ 181 run->mmio.is_write = is_write; 182 run->mmio.phys_addr = fault_ipa; 183 run->mmio.len = len; 184 vcpu->mmio_needed = 1; 185 186 if (!ret) { 187 /* We handled the access successfully in the kernel. */ 188 if (!is_write) 189 memcpy(run->mmio.data, data_buf, len); 190 vcpu->stat.mmio_exit_kernel++; 191 kvm_handle_mmio_return(vcpu, run); 192 return 1; 193 } 194 195 if (is_write) 196 memcpy(run->mmio.data, data_buf, len); 197 vcpu->stat.mmio_exit_user++; 198 run->exit_reason = KVM_EXIT_MMIO; 199 return 0; 200 } 201