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 */ 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 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 */ 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 } 133 134 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 } 184 185 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 */ 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 } 219 220 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 } 232 233 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); 242 243 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); 252 253 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