1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Debug and Guest Debug support
4 *
5 * Copyright (C) 2015 - Linaro Ltd
6 * Authors: Alex Bennée <alex.bennee@linaro.org>
7 * Oliver Upton <oliver.upton@linux.dev>
8 */
9
10 #include <linux/kvm_host.h>
11 #include <linux/hw_breakpoint.h>
12
13 #include <asm/debug-monitors.h>
14 #include <asm/kvm_asm.h>
15 #include <asm/kvm_arm.h>
16 #include <asm/kvm_emulate.h>
17
18 /**
19 * kvm_arm_setup_mdcr_el2 - configure vcpu mdcr_el2 value
20 *
21 * @vcpu: the vcpu pointer
22 *
23 * This ensures we will trap access to:
24 * - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR)
25 * - Debug ROM Address (MDCR_EL2_TDRA)
26 * - OS related registers (MDCR_EL2_TDOSA)
27 * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
28 * - Self-hosted Trace Filter controls (MDCR_EL2_TTRF)
29 * - Self-hosted Trace (MDCR_EL2_TTRF/MDCR_EL2_E2TB)
30 */
kvm_arm_setup_mdcr_el2(struct kvm_vcpu * vcpu)31 static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu)
32 {
33 preempt_disable();
34
35 /*
36 * This also clears MDCR_EL2_E2PB_MASK and MDCR_EL2_E2TB_MASK
37 * to disable guest access to the profiling and trace buffers
38 */
39 vcpu->arch.mdcr_el2 = FIELD_PREP(MDCR_EL2_HPMN,
40 *host_data_ptr(nr_event_counters));
41 vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
42 MDCR_EL2_TPMS |
43 MDCR_EL2_TTRF |
44 MDCR_EL2_TPMCR |
45 MDCR_EL2_TDRA |
46 MDCR_EL2_TDOSA);
47
48 /* Is the VM being debugged by userspace? */
49 if (vcpu->guest_debug)
50 /* Route all software debug exceptions to EL2 */
51 vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE;
52
53 /*
54 * Trap debug registers if the guest doesn't have ownership of them.
55 */
56 if (!kvm_guest_owns_debug_regs(vcpu))
57 vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
58
59 /* Write MDCR_EL2 directly if we're already at EL2 */
60 if (has_vhe())
61 write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
62
63 preempt_enable();
64 }
65
kvm_init_host_debug_data(void)66 void kvm_init_host_debug_data(void)
67 {
68 u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
69
70 if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0)
71 *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N,
72 read_sysreg(pmcr_el0));
73
74 *host_data_ptr(debug_brps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr0);
75 *host_data_ptr(debug_wrps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr0);
76
77 if (has_vhe())
78 return;
79
80 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_PMSVer_SHIFT) &&
81 !(read_sysreg_s(SYS_PMBIDR_EL1) & PMBIDR_EL1_P))
82 host_data_set_flag(HAS_SPE);
83
84 /* Check if we have BRBE implemented and available at the host */
85 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_BRBE_SHIFT))
86 host_data_set_flag(HAS_BRBE);
87
88 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceFilt_SHIFT)) {
89 /* Force disable trace in protected mode in case of no TRBE */
90 if (is_protected_kvm_enabled())
91 host_data_set_flag(EL1_TRACING_CONFIGURED);
92
93 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffer_SHIFT) &&
94 !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P))
95 host_data_set_flag(HAS_TRBE);
96 }
97 }
98
99 /*
100 * Configures the 'external' MDSCR_EL1 value for the guest, i.e. when the host
101 * has taken over MDSCR_EL1.
102 *
103 * - Userspace is single-stepping the guest, and MDSCR_EL1.SS is forced to 1.
104 *
105 * - Userspace is using the breakpoint/watchpoint registers to debug the
106 * guest, and MDSCR_EL1.MDE is forced to 1.
107 *
108 * - The guest has enabled the OS Lock, and KVM is forcing MDSCR_EL1.MDE to 0,
109 * masking all debug exceptions affected by the OS Lock.
110 */
setup_external_mdscr(struct kvm_vcpu * vcpu)111 static void setup_external_mdscr(struct kvm_vcpu *vcpu)
112 {
113 /*
114 * Use the guest's MDSCR_EL1 as a starting point, since there are
115 * several other features controlled by MDSCR_EL1 that are not relevant
116 * to the host.
117 *
118 * Clear the bits that KVM may use which also satisfies emulation of
119 * the OS Lock as MDSCR_EL1.MDE is cleared.
120 */
121 u64 mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1) & ~(MDSCR_EL1_SS |
122 MDSCR_EL1_MDE |
123 MDSCR_EL1_KDE);
124
125 if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
126 mdscr |= MDSCR_EL1_SS;
127
128 if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW)
129 mdscr |= MDSCR_EL1_MDE | MDSCR_EL1_KDE;
130
131 vcpu->arch.external_mdscr_el1 = mdscr;
132 }
133
kvm_vcpu_load_debug(struct kvm_vcpu * vcpu)134 void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu)
135 {
136 u64 mdscr;
137
138 /* Must be called before kvm_vcpu_load_vhe() */
139 KVM_BUG_ON(vcpu_get_flag(vcpu, SYSREGS_ON_CPU), vcpu->kvm);
140
141 /*
142 * Determine which of the possible debug states we're in:
143 *
144 * - VCPU_DEBUG_HOST_OWNED: KVM has taken ownership of the guest's
145 * breakpoint/watchpoint registers, or needs to use MDSCR_EL1 to do
146 * software step or emulate the effects of the OS Lock being enabled.
147 *
148 * - VCPU_DEBUG_GUEST_OWNED: The guest has debug exceptions enabled, and
149 * the breakpoint/watchpoint registers need to be loaded eagerly.
150 *
151 * - VCPU_DEBUG_FREE: Neither of the above apply, no breakpoint/watchpoint
152 * context needs to be loaded on the CPU.
153 */
154 if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) {
155 vcpu->arch.debug_owner = VCPU_DEBUG_HOST_OWNED;
156 setup_external_mdscr(vcpu);
157
158 /*
159 * Steal the guest's single-step state machine if userspace wants
160 * single-step the guest.
161 */
162 if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
163 if (*vcpu_cpsr(vcpu) & DBG_SPSR_SS)
164 vcpu_clear_flag(vcpu, GUEST_SS_ACTIVE_PENDING);
165 else
166 vcpu_set_flag(vcpu, GUEST_SS_ACTIVE_PENDING);
167
168 if (!vcpu_get_flag(vcpu, HOST_SS_ACTIVE_PENDING))
169 *vcpu_cpsr(vcpu) |= DBG_SPSR_SS;
170 else
171 *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
172 }
173 } else {
174 mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
175
176 if (mdscr & (MDSCR_EL1_KDE | MDSCR_EL1_MDE))
177 vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED;
178 else
179 vcpu->arch.debug_owner = VCPU_DEBUG_FREE;
180 }
181
182 kvm_arm_setup_mdcr_el2(vcpu);
183 }
184
kvm_vcpu_put_debug(struct kvm_vcpu * vcpu)185 void kvm_vcpu_put_debug(struct kvm_vcpu *vcpu)
186 {
187 if (likely(!(vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)))
188 return;
189
190 /*
191 * Save the host's software step state and restore the guest's before
192 * potentially returning to userspace.
193 */
194 if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS))
195 vcpu_set_flag(vcpu, HOST_SS_ACTIVE_PENDING);
196 else
197 vcpu_clear_flag(vcpu, HOST_SS_ACTIVE_PENDING);
198
199 if (vcpu_get_flag(vcpu, GUEST_SS_ACTIVE_PENDING))
200 *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
201 else
202 *vcpu_cpsr(vcpu) |= DBG_SPSR_SS;
203 }
204
205 /*
206 * Updates ownership of the debug registers after a trapped guest access to a
207 * breakpoint/watchpoint register. Host ownership of the debug registers is of
208 * strictly higher priority, and it is the responsibility of the VMM to emulate
209 * guest debug exceptions in this configuration.
210 */
kvm_debug_set_guest_ownership(struct kvm_vcpu * vcpu)211 void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu)
212 {
213 if (kvm_host_owns_debug_regs(vcpu))
214 return;
215
216 vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED;
217 kvm_arm_setup_mdcr_el2(vcpu);
218 }
219
kvm_debug_handle_oslar(struct kvm_vcpu * vcpu,u64 val)220 void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val)
221 {
222 if (val & OSLAR_EL1_OSLK)
223 __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, |=, OSLSR_EL1_OSLK);
224 else
225 __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, &=, ~OSLSR_EL1_OSLK);
226
227 preempt_disable();
228 kvm_arch_vcpu_put(vcpu);
229 kvm_arch_vcpu_load(vcpu, smp_processor_id());
230 preempt_enable();
231 }
232
kvm_enable_trbe(void)233 void kvm_enable_trbe(void)
234 {
235 if (has_vhe() || is_protected_kvm_enabled() ||
236 WARN_ON_ONCE(preemptible()))
237 return;
238
239 host_data_set_flag(TRBE_ENABLED);
240 }
241 EXPORT_SYMBOL_GPL(kvm_enable_trbe);
242
kvm_disable_trbe(void)243 void kvm_disable_trbe(void)
244 {
245 if (has_vhe() || is_protected_kvm_enabled() ||
246 WARN_ON_ONCE(preemptible()))
247 return;
248
249 host_data_clear_flag(TRBE_ENABLED);
250 }
251 EXPORT_SYMBOL_GPL(kvm_disable_trbe);
252
kvm_tracing_set_el1_configuration(u64 trfcr_while_in_guest)253 void kvm_tracing_set_el1_configuration(u64 trfcr_while_in_guest)
254 {
255 if (is_protected_kvm_enabled() || WARN_ON_ONCE(preemptible()))
256 return;
257
258 if (has_vhe()) {
259 write_sysreg_s(trfcr_while_in_guest, SYS_TRFCR_EL12);
260 return;
261 }
262
263 *host_data_ptr(trfcr_while_in_guest) = trfcr_while_in_guest;
264 if (read_sysreg_s(SYS_TRFCR_EL1) != trfcr_while_in_guest)
265 host_data_set_flag(EL1_TRACING_CONFIGURED);
266 else
267 host_data_clear_flag(EL1_TRACING_CONFIGURED);
268 }
269 EXPORT_SYMBOL_GPL(kvm_tracing_set_el1_configuration);
270