Merge tag 'rpmsg-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc...
[linux-2.6-microblaze.git] / arch / arm64 / kvm / debug.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Debug and Guest Debug support
4  *
5  * Copyright (C) 2015 - Linaro Ltd
6  * Author: Alex BennĂ©e <alex.bennee@linaro.org>
7  */
8
9 #include <linux/kvm_host.h>
10 #include <linux/hw_breakpoint.h>
11
12 #include <asm/debug-monitors.h>
13 #include <asm/kvm_asm.h>
14 #include <asm/kvm_arm.h>
15 #include <asm/kvm_emulate.h>
16
17 #include "trace.h"
18
19 /* These are the bits of MDSCR_EL1 we may manipulate */
20 #define MDSCR_EL1_DEBUG_MASK    (DBG_MDSCR_SS | \
21                                 DBG_MDSCR_KDE | \
22                                 DBG_MDSCR_MDE)
23
24 static DEFINE_PER_CPU(u64, mdcr_el2);
25
26 /**
27  * save/restore_guest_debug_regs
28  *
29  * For some debug operations we need to tweak some guest registers. As
30  * a result we need to save the state of those registers before we
31  * make those modifications.
32  *
33  * Guest access to MDSCR_EL1 is trapped by the hypervisor and handled
34  * after we have restored the preserved value to the main context.
35  */
36 static void save_guest_debug_regs(struct kvm_vcpu *vcpu)
37 {
38         u64 val = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
39
40         vcpu->arch.guest_debug_preserved.mdscr_el1 = val;
41
42         trace_kvm_arm_set_dreg32("Saved MDSCR_EL1",
43                                 vcpu->arch.guest_debug_preserved.mdscr_el1);
44 }
45
46 static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
47 {
48         u64 val = vcpu->arch.guest_debug_preserved.mdscr_el1;
49
50         vcpu_write_sys_reg(vcpu, val, MDSCR_EL1);
51
52         trace_kvm_arm_set_dreg32("Restored MDSCR_EL1",
53                                 vcpu_read_sys_reg(vcpu, MDSCR_EL1));
54 }
55
56 /**
57  * kvm_arm_init_debug - grab what we need for debug
58  *
59  * Currently the sole task of this function is to retrieve the initial
60  * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
61  * presumably been set-up by some knowledgeable bootcode.
62  *
63  * It is called once per-cpu during CPU hyp initialisation.
64  */
65
66 void kvm_arm_init_debug(void)
67 {
68         __this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2));
69 }
70
71 /**
72  * kvm_arm_setup_mdcr_el2 - configure vcpu mdcr_el2 value
73  *
74  * @vcpu:       the vcpu pointer
75  *
76  * This ensures we will trap access to:
77  *  - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR)
78  *  - Debug ROM Address (MDCR_EL2_TDRA)
79  *  - OS related registers (MDCR_EL2_TDOSA)
80  *  - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
81  *  - Self-hosted Trace Filter controls (MDCR_EL2_TTRF)
82  *  - Self-hosted Trace (MDCR_EL2_TTRF/MDCR_EL2_E2TB)
83  */
84 static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu)
85 {
86         /*
87          * This also clears MDCR_EL2_E2PB_MASK and MDCR_EL2_E2TB_MASK
88          * to disable guest access to the profiling and trace buffers
89          */
90         vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
91         vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
92                                 MDCR_EL2_TPMS |
93                                 MDCR_EL2_TTRF |
94                                 MDCR_EL2_TPMCR |
95                                 MDCR_EL2_TDRA |
96                                 MDCR_EL2_TDOSA);
97
98         /* Is the VM being debugged by userspace? */
99         if (vcpu->guest_debug)
100                 /* Route all software debug exceptions to EL2 */
101                 vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE;
102
103         /*
104          * Trap debug register access when one of the following is true:
105          *  - Userspace is using the hardware to debug the guest
106          *  (KVM_GUESTDBG_USE_HW is set).
107          *  - The guest is not using debug (KVM_ARM64_DEBUG_DIRTY is clear).
108          *  - The guest has enabled the OS Lock (debug exceptions are blocked).
109          */
110         if ((vcpu->guest_debug & KVM_GUESTDBG_USE_HW) ||
111             !(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY) ||
112             kvm_vcpu_os_lock_enabled(vcpu))
113                 vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
114
115         trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2);
116 }
117
118 /**
119  * kvm_arm_vcpu_init_debug - setup vcpu debug traps
120  *
121  * @vcpu:       the vcpu pointer
122  *
123  * Set vcpu initial mdcr_el2 value.
124  */
125 void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu)
126 {
127         preempt_disable();
128         kvm_arm_setup_mdcr_el2(vcpu);
129         preempt_enable();
130 }
131
132 /**
133  * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state
134  */
135
136 void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
137 {
138         vcpu->arch.debug_ptr = &vcpu->arch.vcpu_debug_state;
139 }
140
141 /**
142  * kvm_arm_setup_debug - set up debug related stuff
143  *
144  * @vcpu:       the vcpu pointer
145  *
146  * This is called before each entry into the hypervisor to setup any
147  * debug related registers.
148  *
149  * Additionally, KVM only traps guest accesses to the debug registers if
150  * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY
151  * flag on vcpu->arch.flags).  Since the guest must not interfere
152  * with the hardware state when debugging the guest, we must ensure that
153  * trapping is enabled whenever we are debugging the guest using the
154  * debug registers.
155  */
156
157 void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
158 {
159         unsigned long mdscr, orig_mdcr_el2 = vcpu->arch.mdcr_el2;
160
161         trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug);
162
163         kvm_arm_setup_mdcr_el2(vcpu);
164
165         /* Check if we need to use the debug registers. */
166         if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) {
167                 /* Save guest debug state */
168                 save_guest_debug_regs(vcpu);
169
170                 /*
171                  * Single Step (ARM ARM D2.12.3 The software step state
172                  * machine)
173                  *
174                  * If we are doing Single Step we need to manipulate
175                  * the guest's MDSCR_EL1.SS and PSTATE.SS. Once the
176                  * step has occurred the hypervisor will trap the
177                  * debug exception and we return to userspace.
178                  *
179                  * If the guest attempts to single step its userspace
180                  * we would have to deal with a trapped exception
181                  * while in the guest kernel. Because this would be
182                  * hard to unwind we suppress the guest's ability to
183                  * do so by masking MDSCR_EL.SS.
184                  *
185                  * This confuses guest debuggers which use
186                  * single-step behind the scenes but everything
187                  * returns to normal once the host is no longer
188                  * debugging the system.
189                  */
190                 if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
191                         *vcpu_cpsr(vcpu) |=  DBG_SPSR_SS;
192                         mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
193                         mdscr |= DBG_MDSCR_SS;
194                         vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);
195                 } else {
196                         mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
197                         mdscr &= ~DBG_MDSCR_SS;
198                         vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);
199                 }
200
201                 trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu));
202
203                 /*
204                  * HW Breakpoints and watchpoints
205                  *
206                  * We simply switch the debug_ptr to point to our new
207                  * external_debug_state which has been populated by the
208                  * debug ioctl. The existing KVM_ARM64_DEBUG_DIRTY
209                  * mechanism ensures the registers are updated on the
210                  * world switch.
211                  */
212                 if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) {
213                         /* Enable breakpoints/watchpoints */
214                         mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
215                         mdscr |= DBG_MDSCR_MDE;
216                         vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);
217
218                         vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state;
219                         vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
220
221                         trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
222                                                 &vcpu->arch.debug_ptr->dbg_bcr[0],
223                                                 &vcpu->arch.debug_ptr->dbg_bvr[0]);
224
225                         trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
226                                                 &vcpu->arch.debug_ptr->dbg_wcr[0],
227                                                 &vcpu->arch.debug_ptr->dbg_wvr[0]);
228
229                 /*
230                  * The OS Lock blocks debug exceptions in all ELs when it is
231                  * enabled. If the guest has enabled the OS Lock, constrain its
232                  * effects to the guest. Emulate the behavior by clearing
233                  * MDSCR_EL1.MDE. In so doing, we ensure that host debug
234                  * exceptions are unaffected by guest configuration of the OS
235                  * Lock.
236                  */
237                 } else if (kvm_vcpu_os_lock_enabled(vcpu)) {
238                         mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
239                         mdscr &= ~DBG_MDSCR_MDE;
240                         vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);
241                 }
242         }
243
244         BUG_ON(!vcpu->guest_debug &&
245                 vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state);
246
247         /* If KDE or MDE are set, perform a full save/restore cycle. */
248         if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE))
249                 vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
250
251         /* Write mdcr_el2 changes since vcpu_load on VHE systems */
252         if (has_vhe() && orig_mdcr_el2 != vcpu->arch.mdcr_el2)
253                 write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
254
255         trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1));
256 }
257
258 void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
259 {
260         trace_kvm_arm_clear_debug(vcpu->guest_debug);
261
262         /*
263          * Restore the guest's debug registers if we were using them.
264          */
265         if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) {
266                 restore_guest_debug_regs(vcpu);
267
268                 /*
269                  * If we were using HW debug we need to restore the
270                  * debug_ptr to the guest debug state.
271                  */
272                 if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) {
273                         kvm_arm_reset_debug_ptr(vcpu);
274
275                         trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
276                                                 &vcpu->arch.debug_ptr->dbg_bcr[0],
277                                                 &vcpu->arch.debug_ptr->dbg_bvr[0]);
278
279                         trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
280                                                 &vcpu->arch.debug_ptr->dbg_wcr[0],
281                                                 &vcpu->arch.debug_ptr->dbg_wvr[0]);
282                 }
283         }
284 }
285
286 void kvm_arch_vcpu_load_debug_state_flags(struct kvm_vcpu *vcpu)
287 {
288         u64 dfr0;
289
290         /* For VHE, there is nothing to do */
291         if (has_vhe())
292                 return;
293
294         dfr0 = read_sysreg(id_aa64dfr0_el1);
295         /*
296          * If SPE is present on this CPU and is available at current EL,
297          * we may need to check if the host state needs to be saved.
298          */
299         if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_PMSVER_SHIFT) &&
300             !(read_sysreg_s(SYS_PMBIDR_EL1) & BIT(SYS_PMBIDR_EL1_P_SHIFT)))
301                 vcpu->arch.flags |= KVM_ARM64_DEBUG_STATE_SAVE_SPE;
302
303         /* Check if we have TRBE implemented and available at the host */
304         if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_TRBE_SHIFT) &&
305             !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_PROG))
306                 vcpu->arch.flags |= KVM_ARM64_DEBUG_STATE_SAVE_TRBE;
307 }
308
309 void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu)
310 {
311         vcpu->arch.flags &= ~(KVM_ARM64_DEBUG_STATE_SAVE_SPE |
312                               KVM_ARM64_DEBUG_STATE_SAVE_TRBE);
313 }