1 /*
2 * Copyright (C) 2012,2013 - ARM Ltd
3 * Author: Marc Zyngier <marc.zyngier@arm.com>
4 *
5 * Derived from arch/arm/kvm/handle_exit.c:
6 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
7 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program. If not, see <http://www.gnu.org/licenses/>.
20 */
21
22 #include <linux/kvm.h>
23 #include <linux/kvm_host.h>
24
25 #include <kvm/arm_psci.h>
26
27 #include <asm/esr.h>
28 #include <asm/kvm_asm.h>
29 #include <asm/kvm_coproc.h>
30 #include <asm/kvm_emulate.h>
31 #include <asm/kvm_mmu.h>
32
33 #define CREATE_TRACE_POINTS
34 #include "trace.h"
35
36 typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);
37
handle_hvc(struct kvm_vcpu * vcpu,struct kvm_run * run)38 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
39 {
40 int ret;
41
42 trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
43 kvm_vcpu_hvc_get_imm(vcpu));
44 vcpu->stat.hvc_exit_stat++;
45
46 ret = kvm_hvc_call_handler(vcpu);
47 if (ret < 0) {
48 vcpu_set_reg(vcpu, 0, ~0UL);
49 return 1;
50 }
51
52 return ret;
53 }
54
handle_smc(struct kvm_vcpu * vcpu,struct kvm_run * run)55 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
56 {
57 /*
58 * "If an SMC instruction executed at Non-secure EL1 is
59 * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
60 * Trap exception, not a Secure Monitor Call exception [...]"
61 *
62 * We need to advance the PC after the trap, as it would
63 * otherwise return to the same address...
64 */
65 vcpu_set_reg(vcpu, 0, ~0UL);
66 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
67 return 1;
68 }
69
70 /*
71 * Guest access to FP/ASIMD registers are routed to this handler only
72 * when the system doesn't support FP/ASIMD.
73 */
handle_no_fpsimd(struct kvm_vcpu * vcpu,struct kvm_run * run)74 static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run)
75 {
76 kvm_inject_undefined(vcpu);
77 return 1;
78 }
79
80 /**
81 * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
82 * instruction executed by a guest
83 *
84 * @vcpu: the vcpu pointer
85 *
86 * WFE: Yield the CPU and come back to this vcpu when the scheduler
87 * decides to.
88 * WFI: Simply call kvm_vcpu_block(), which will halt execution of
89 * world-switches and schedule other host processes until there is an
90 * incoming IRQ or FIQ to the VM.
91 */
kvm_handle_wfx(struct kvm_vcpu * vcpu,struct kvm_run * run)92 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
93 {
94 if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
95 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
96 vcpu->stat.wfe_exit_stat++;
97 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
98 } else {
99 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
100 vcpu->stat.wfi_exit_stat++;
101 kvm_vcpu_block(vcpu);
102 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
103 }
104
105 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
106
107 return 1;
108 }
109
110 /**
111 * kvm_handle_guest_debug - handle a debug exception instruction
112 *
113 * @vcpu: the vcpu pointer
114 * @run: access to the kvm_run structure for results
115 *
116 * We route all debug exceptions through the same handler. If both the
117 * guest and host are using the same debug facilities it will be up to
118 * userspace to re-inject the correct exception for guest delivery.
119 *
120 * @return: 0 (while setting run->exit_reason), -1 for error
121 */
kvm_handle_guest_debug(struct kvm_vcpu * vcpu,struct kvm_run * run)122 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run)
123 {
124 u32 hsr = kvm_vcpu_get_hsr(vcpu);
125 int ret = 0;
126
127 run->exit_reason = KVM_EXIT_DEBUG;
128 run->debug.arch.hsr = hsr;
129
130 switch (ESR_ELx_EC(hsr)) {
131 case ESR_ELx_EC_WATCHPT_LOW:
132 run->debug.arch.far = vcpu->arch.fault.far_el2;
133 /* fall through */
134 case ESR_ELx_EC_SOFTSTP_LOW:
135 case ESR_ELx_EC_BREAKPT_LOW:
136 case ESR_ELx_EC_BKPT32:
137 case ESR_ELx_EC_BRK64:
138 break;
139 default:
140 kvm_err("%s: un-handled case hsr: %#08x\n",
141 __func__, (unsigned int) hsr);
142 ret = -1;
143 break;
144 }
145
146 return ret;
147 }
148
kvm_handle_unknown_ec(struct kvm_vcpu * vcpu,struct kvm_run * run)149 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
150 {
151 u32 hsr = kvm_vcpu_get_hsr(vcpu);
152
153 kvm_pr_unimpl("Unknown exception class: hsr: %#08x -- %s\n",
154 hsr, esr_get_class_string(hsr));
155
156 kvm_inject_undefined(vcpu);
157 return 1;
158 }
159
160 static exit_handle_fn arm_exit_handlers[] = {
161 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
162 [ESR_ELx_EC_WFx] = kvm_handle_wfx,
163 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32,
164 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64,
165 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32,
166 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store,
167 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64,
168 [ESR_ELx_EC_HVC32] = handle_hvc,
169 [ESR_ELx_EC_SMC32] = handle_smc,
170 [ESR_ELx_EC_HVC64] = handle_hvc,
171 [ESR_ELx_EC_SMC64] = handle_smc,
172 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg,
173 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort,
174 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort,
175 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
176 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
177 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
178 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug,
179 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug,
180 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd,
181 };
182
kvm_get_exit_handler(struct kvm_vcpu * vcpu)183 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
184 {
185 u32 hsr = kvm_vcpu_get_hsr(vcpu);
186 u8 hsr_ec = ESR_ELx_EC(hsr);
187
188 return arm_exit_handlers[hsr_ec];
189 }
190
191 /*
192 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
193 * proper exit to userspace.
194 */
handle_exit(struct kvm_vcpu * vcpu,struct kvm_run * run,int exception_index)195 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
196 int exception_index)
197 {
198 exit_handle_fn exit_handler;
199
200 if (ARM_SERROR_PENDING(exception_index)) {
201 u8 hsr_ec = ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu));
202
203 /*
204 * HVC/SMC already have an adjusted PC, which we need
205 * to correct in order to return to after having
206 * injected the SError.
207 */
208 if (hsr_ec == ESR_ELx_EC_HVC32 || hsr_ec == ESR_ELx_EC_HVC64 ||
209 hsr_ec == ESR_ELx_EC_SMC32 || hsr_ec == ESR_ELx_EC_SMC64) {
210 u32 adj = kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
211 *vcpu_pc(vcpu) -= adj;
212 }
213
214 kvm_inject_vabt(vcpu);
215 return 1;
216 }
217
218 exception_index = ARM_EXCEPTION_CODE(exception_index);
219
220 switch (exception_index) {
221 case ARM_EXCEPTION_IRQ:
222 return 1;
223 case ARM_EXCEPTION_EL1_SERROR:
224 kvm_inject_vabt(vcpu);
225 return 1;
226 case ARM_EXCEPTION_TRAP:
227 /*
228 * See ARM ARM B1.14.1: "Hyp traps on instructions
229 * that fail their condition code check"
230 */
231 if (!kvm_condition_valid(vcpu)) {
232 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
233 return 1;
234 }
235
236 exit_handler = kvm_get_exit_handler(vcpu);
237
238 return exit_handler(vcpu, run);
239 case ARM_EXCEPTION_HYP_GONE:
240 /*
241 * EL2 has been reset to the hyp-stub. This happens when a guest
242 * is pre-empted by kvm_reboot()'s shutdown call.
243 */
244 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
245 return 0;
246 default:
247 kvm_pr_unimpl("Unsupported exception type: %d",
248 exception_index);
249 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
250 return 0;
251 }
252 }
253