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Linux/arch/arm64/kvm/handle_exit.c

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  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/exception.h>
 29 #include <asm/kvm_asm.h>
 30 #include <asm/kvm_coproc.h>
 31 #include <asm/kvm_emulate.h>
 32 #include <asm/kvm_mmu.h>
 33 #include <asm/debug-monitors.h>
 34 #include <asm/traps.h>
 35 
 36 #define CREATE_TRACE_POINTS
 37 #include "trace.h"
 38 
 39 typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);
 40 
 41 static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr)
 42 {
 43         if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr))
 44                 kvm_inject_vabt(vcpu);
 45 }
 46 
 47 static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 48 {
 49         int ret;
 50 
 51         trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
 52                             kvm_vcpu_hvc_get_imm(vcpu));
 53         vcpu->stat.hvc_exit_stat++;
 54 
 55         ret = kvm_hvc_call_handler(vcpu);
 56         if (ret < 0) {
 57                 vcpu_set_reg(vcpu, 0, ~0UL);
 58                 return 1;
 59         }
 60 
 61         return ret;
 62 }
 63 
 64 static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
 65 {
 66         /*
 67          * "If an SMC instruction executed at Non-secure EL1 is
 68          * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
 69          * Trap exception, not a Secure Monitor Call exception [...]"
 70          *
 71          * We need to advance the PC after the trap, as it would
 72          * otherwise return to the same address...
 73          */
 74         vcpu_set_reg(vcpu, 0, ~0UL);
 75         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
 76         return 1;
 77 }
 78 
 79 /*
 80  * Guest access to FP/ASIMD registers are routed to this handler only
 81  * when the system doesn't support FP/ASIMD.
 82  */
 83 static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run)
 84 {
 85         kvm_inject_undefined(vcpu);
 86         return 1;
 87 }
 88 
 89 /**
 90  * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
 91  *                  instruction executed by a guest
 92  *
 93  * @vcpu:       the vcpu pointer
 94  *
 95  * WFE: Yield the CPU and come back to this vcpu when the scheduler
 96  * decides to.
 97  * WFI: Simply call kvm_vcpu_block(), which will halt execution of
 98  * world-switches and schedule other host processes until there is an
 99  * incoming IRQ or FIQ to the VM.
100  */
101 static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
102 {
103         if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
104                 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
105                 vcpu->stat.wfe_exit_stat++;
106                 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
107         } else {
108                 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
109                 vcpu->stat.wfi_exit_stat++;
110                 kvm_vcpu_block(vcpu);
111                 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
112         }
113 
114         kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
115 
116         return 1;
117 }
118 
119 /**
120  * kvm_handle_guest_debug - handle a debug exception instruction
121  *
122  * @vcpu:       the vcpu pointer
123  * @run:        access to the kvm_run structure for results
124  *
125  * We route all debug exceptions through the same handler. If both the
126  * guest and host are using the same debug facilities it will be up to
127  * userspace to re-inject the correct exception for guest delivery.
128  *
129  * @return: 0 (while setting run->exit_reason), -1 for error
130  */
131 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run)
132 {
133         u32 hsr = kvm_vcpu_get_hsr(vcpu);
134         int ret = 0;
135 
136         run->exit_reason = KVM_EXIT_DEBUG;
137         run->debug.arch.hsr = hsr;
138 
139         switch (ESR_ELx_EC(hsr)) {
140         case ESR_ELx_EC_WATCHPT_LOW:
141                 run->debug.arch.far = vcpu->arch.fault.far_el2;
142                 /* fall through */
143         case ESR_ELx_EC_SOFTSTP_LOW:
144         case ESR_ELx_EC_BREAKPT_LOW:
145         case ESR_ELx_EC_BKPT32:
146         case ESR_ELx_EC_BRK64:
147                 break;
148         default:
149                 kvm_err("%s: un-handled case hsr: %#08x\n",
150                         __func__, (unsigned int) hsr);
151                 ret = -1;
152                 break;
153         }
154 
155         return ret;
156 }
157 
158 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu, struct kvm_run *run)
159 {
160         u32 hsr = kvm_vcpu_get_hsr(vcpu);
161 
162         kvm_pr_unimpl("Unknown exception class: hsr: %#08x -- %s\n",
163                       hsr, esr_get_class_string(hsr));
164 
165         kvm_inject_undefined(vcpu);
166         return 1;
167 }
168 
169 static int handle_sve(struct kvm_vcpu *vcpu, struct kvm_run *run)
170 {
171         /* Until SVE is supported for guests: */
172         kvm_inject_undefined(vcpu);
173         return 1;
174 }
175 
176 static exit_handle_fn arm_exit_handlers[] = {
177         [0 ... ESR_ELx_EC_MAX]  = kvm_handle_unknown_ec,
178         [ESR_ELx_EC_WFx]        = kvm_handle_wfx,
179         [ESR_ELx_EC_CP15_32]    = kvm_handle_cp15_32,
180         [ESR_ELx_EC_CP15_64]    = kvm_handle_cp15_64,
181         [ESR_ELx_EC_CP14_MR]    = kvm_handle_cp14_32,
182         [ESR_ELx_EC_CP14_LS]    = kvm_handle_cp14_load_store,
183         [ESR_ELx_EC_CP14_64]    = kvm_handle_cp14_64,
184         [ESR_ELx_EC_HVC32]      = handle_hvc,
185         [ESR_ELx_EC_SMC32]      = handle_smc,
186         [ESR_ELx_EC_HVC64]      = handle_hvc,
187         [ESR_ELx_EC_SMC64]      = handle_smc,
188         [ESR_ELx_EC_SYS64]      = kvm_handle_sys_reg,
189         [ESR_ELx_EC_SVE]        = handle_sve,
190         [ESR_ELx_EC_IABT_LOW]   = kvm_handle_guest_abort,
191         [ESR_ELx_EC_DABT_LOW]   = kvm_handle_guest_abort,
192         [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
193         [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
194         [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
195         [ESR_ELx_EC_BKPT32]     = kvm_handle_guest_debug,
196         [ESR_ELx_EC_BRK64]      = kvm_handle_guest_debug,
197         [ESR_ELx_EC_FP_ASIMD]   = handle_no_fpsimd,
198 };
199 
200 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
201 {
202         u32 hsr = kvm_vcpu_get_hsr(vcpu);
203         u8 hsr_ec = ESR_ELx_EC(hsr);
204 
205         return arm_exit_handlers[hsr_ec];
206 }
207 
208 /*
209  * We may be single-stepping an emulated instruction. If the emulation
210  * has been completed in the kernel, we can return to userspace with a
211  * KVM_EXIT_DEBUG, otherwise userspace needs to complete its
212  * emulation first.
213  */
214 static int handle_trap_exceptions(struct kvm_vcpu *vcpu, struct kvm_run *run)
215 {
216         int handled;
217 
218         /*
219          * See ARM ARM B1.14.1: "Hyp traps on instructions
220          * that fail their condition code check"
221          */
222         if (!kvm_condition_valid(vcpu)) {
223                 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
224                 handled = 1;
225         } else {
226                 exit_handle_fn exit_handler;
227 
228                 exit_handler = kvm_get_exit_handler(vcpu);
229                 handled = exit_handler(vcpu, run);
230         }
231 
232         /*
233          * kvm_arm_handle_step_debug() sets the exit_reason on the kvm_run
234          * structure if we need to return to userspace.
235          */
236         if (handled > 0 && kvm_arm_handle_step_debug(vcpu, run))
237                 handled = 0;
238 
239         return handled;
240 }
241 
242 /*
243  * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
244  * proper exit to userspace.
245  */
246 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
247                        int exception_index)
248 {
249         if (ARM_SERROR_PENDING(exception_index)) {
250                 u8 hsr_ec = ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu));
251 
252                 /*
253                  * HVC/SMC already have an adjusted PC, which we need
254                  * to correct in order to return to after having
255                  * injected the SError.
256                  */
257                 if (hsr_ec == ESR_ELx_EC_HVC32 || hsr_ec == ESR_ELx_EC_HVC64 ||
258                     hsr_ec == ESR_ELx_EC_SMC32 || hsr_ec == ESR_ELx_EC_SMC64) {
259                         u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
260                         *vcpu_pc(vcpu) -= adj;
261                 }
262 
263                 return 1;
264         }
265 
266         exception_index = ARM_EXCEPTION_CODE(exception_index);
267 
268         switch (exception_index) {
269         case ARM_EXCEPTION_IRQ:
270                 return 1;
271         case ARM_EXCEPTION_EL1_SERROR:
272                 /* We may still need to return for single-step */
273                 if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS)
274                         && kvm_arm_handle_step_debug(vcpu, run))
275                         return 0;
276                 else
277                         return 1;
278         case ARM_EXCEPTION_TRAP:
279                 return handle_trap_exceptions(vcpu, run);
280         case ARM_EXCEPTION_HYP_GONE:
281                 /*
282                  * EL2 has been reset to the hyp-stub. This happens when a guest
283                  * is pre-empted by kvm_reboot()'s shutdown call.
284                  */
285                 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
286                 return 0;
287         default:
288                 kvm_pr_unimpl("Unsupported exception type: %d",
289                               exception_index);
290                 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
291                 return 0;
292         }
293 }
294 
295 /* For exit types that need handling before we can be preempted */
296 void handle_exit_early(struct kvm_vcpu *vcpu, struct kvm_run *run,
297                        int exception_index)
298 {
299         if (ARM_SERROR_PENDING(exception_index)) {
300                 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) {
301                         u64 disr = kvm_vcpu_get_disr(vcpu);
302 
303                         kvm_handle_guest_serror(vcpu, disr_to_esr(disr));
304                 } else {
305                         kvm_inject_vabt(vcpu);
306                 }
307 
308                 return;
309         }
310 
311         exception_index = ARM_EXCEPTION_CODE(exception_index);
312 
313         if (exception_index == ARM_EXCEPTION_EL1_SERROR)
314                 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_hsr(vcpu));
315 }
316 

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