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 if (vcpu_has_nv(vcpu)) 60 kvm_nested_setup_mdcr_el2(vcpu); 61 62 /* Write MDCR_EL2 directly if we're already at EL2 */ 63 if (has_vhe()) 64 write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); 65 66 preempt_enable(); 67 } 68 69 void kvm_init_host_debug_data(void) 70 { 71 u64 dfr0 = read_sysreg(id_aa64dfr0_el1); 72 73 if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0) 74 *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N, 75 read_sysreg(pmcr_el0)); 76 77 *host_data_ptr(debug_brps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr0); 78 *host_data_ptr(debug_wrps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr0); 79 80 if (has_vhe()) 81 return; 82 83 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_PMSVer_SHIFT) && 84 !(read_sysreg_s(SYS_PMBIDR_EL1) & PMBIDR_EL1_P)) 85 host_data_set_flag(HAS_SPE); 86 87 /* Check if we have BRBE implemented and available at the host */ 88 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_BRBE_SHIFT)) 89 host_data_set_flag(HAS_BRBE); 90 91 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceFilt_SHIFT)) { 92 /* Force disable trace in protected mode in case of no TRBE */ 93 if (is_protected_kvm_enabled()) 94 host_data_set_flag(EL1_TRACING_CONFIGURED); 95 96 if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffer_SHIFT) && 97 !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P)) 98 host_data_set_flag(HAS_TRBE); 99 } 100 } 101 102 /* 103 * Configures the 'external' MDSCR_EL1 value for the guest, i.e. when the host 104 * has taken over MDSCR_EL1. 105 * 106 * - Userspace is single-stepping the guest, and MDSCR_EL1.SS is forced to 1. 107 * 108 * - Userspace is using the breakpoint/watchpoint registers to debug the 109 * guest, and MDSCR_EL1.MDE is forced to 1. 110 * 111 * - The guest has enabled the OS Lock, and KVM is forcing MDSCR_EL1.MDE to 0, 112 * masking all debug exceptions affected by the OS Lock. 113 */ 114 static void setup_external_mdscr(struct kvm_vcpu *vcpu) 115 { 116 /* 117 * Use the guest's MDSCR_EL1 as a starting point, since there are 118 * several other features controlled by MDSCR_EL1 that are not relevant 119 * to the host. 120 * 121 * Clear the bits that KVM may use which also satisfies emulation of 122 * the OS Lock as MDSCR_EL1.MDE is cleared. 123 */ 124 u64 mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1) & ~(MDSCR_EL1_SS | 125 MDSCR_EL1_MDE | 126 MDSCR_EL1_KDE); 127 128 if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) 129 mdscr |= MDSCR_EL1_SS; 130 131 if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) 132 mdscr |= MDSCR_EL1_MDE | MDSCR_EL1_KDE; 133 134 vcpu->arch.external_mdscr_el1 = mdscr; 135 } 136 137 void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu) 138 { 139 u64 mdscr; 140 141 /* Must be called before kvm_vcpu_load_vhe() */ 142 KVM_BUG_ON(vcpu_get_flag(vcpu, SYSREGS_ON_CPU), vcpu->kvm); 143 144 /* 145 * Determine which of the possible debug states we're in: 146 * 147 * - VCPU_DEBUG_HOST_OWNED: KVM has taken ownership of the guest's 148 * breakpoint/watchpoint registers, or needs to use MDSCR_EL1 to do 149 * software step or emulate the effects of the OS Lock being enabled. 150 * 151 * - VCPU_DEBUG_GUEST_OWNED: The guest has debug exceptions enabled, and 152 * the breakpoint/watchpoint registers need to be loaded eagerly. 153 * 154 * - VCPU_DEBUG_FREE: Neither of the above apply, no breakpoint/watchpoint 155 * context needs to be loaded on the CPU. 156 */ 157 if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) { 158 vcpu->arch.debug_owner = VCPU_DEBUG_HOST_OWNED; 159 setup_external_mdscr(vcpu); 160 161 /* 162 * Steal the guest's single-step state machine if userspace wants 163 * single-step the guest. 164 */ 165 if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { 166 if (*vcpu_cpsr(vcpu) & DBG_SPSR_SS) 167 vcpu_clear_flag(vcpu, GUEST_SS_ACTIVE_PENDING); 168 else 169 vcpu_set_flag(vcpu, GUEST_SS_ACTIVE_PENDING); 170 171 if (!vcpu_get_flag(vcpu, HOST_SS_ACTIVE_PENDING)) 172 *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; 173 else 174 *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; 175 } 176 } else { 177 mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 178 179 if (mdscr & (MDSCR_EL1_KDE | MDSCR_EL1_MDE)) 180 vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED; 181 else 182 vcpu->arch.debug_owner = VCPU_DEBUG_FREE; 183 } 184 185 kvm_arm_setup_mdcr_el2(vcpu); 186 } 187 188 void kvm_vcpu_put_debug(struct kvm_vcpu *vcpu) 189 { 190 if (likely(!(vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP))) 191 return; 192 193 /* 194 * Save the host's software step state and restore the guest's before 195 * potentially returning to userspace. 196 */ 197 if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS)) 198 vcpu_set_flag(vcpu, HOST_SS_ACTIVE_PENDING); 199 else 200 vcpu_clear_flag(vcpu, HOST_SS_ACTIVE_PENDING); 201 202 if (vcpu_get_flag(vcpu, GUEST_SS_ACTIVE_PENDING)) 203 *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; 204 else 205 *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; 206 } 207 208 /* 209 * Updates ownership of the debug registers after a trapped guest access to a 210 * breakpoint/watchpoint register. Host ownership of the debug registers is of 211 * strictly higher priority, and it is the responsibility of the VMM to emulate 212 * guest debug exceptions in this configuration. 213 */ 214 void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu) 215 { 216 if (kvm_host_owns_debug_regs(vcpu)) 217 return; 218 219 vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED; 220 kvm_arm_setup_mdcr_el2(vcpu); 221 } 222 223 void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val) 224 { 225 if (val & OSLAR_EL1_OSLK) 226 __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, |=, OSLSR_EL1_OSLK); 227 else 228 __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, &=, ~OSLSR_EL1_OSLK); 229 230 preempt_disable(); 231 kvm_arch_vcpu_put(vcpu); 232 kvm_arch_vcpu_load(vcpu, smp_processor_id()); 233 preempt_enable(); 234 } 235 236 static bool skip_trbe_access(bool skip_condition) 237 { 238 return (WARN_ON_ONCE(preemptible()) || skip_condition || 239 is_protected_kvm_enabled() || !is_kvm_arm_initialised()); 240 } 241 242 void kvm_enable_trbe(void) 243 { 244 if (!skip_trbe_access(has_vhe())) 245 host_data_set_flag(TRBE_ENABLED); 246 } 247 EXPORT_SYMBOL_GPL(kvm_enable_trbe); 248 249 void kvm_disable_trbe(void) 250 { 251 if (!skip_trbe_access(has_vhe())) 252 host_data_clear_flag(TRBE_ENABLED); 253 } 254 EXPORT_SYMBOL_GPL(kvm_disable_trbe); 255 256 void kvm_tracing_set_el1_configuration(u64 trfcr_while_in_guest) 257 { 258 if (skip_trbe_access(false)) 259 return; 260 261 if (has_vhe()) { 262 write_sysreg_s(trfcr_while_in_guest, SYS_TRFCR_EL12); 263 return; 264 } 265 266 *host_data_ptr(trfcr_while_in_guest) = trfcr_while_in_guest; 267 if (read_sysreg_s(SYS_TRFCR_EL1) != trfcr_while_in_guest) 268 host_data_set_flag(EL1_TRACING_CONFIGURED); 269 else 270 host_data_clear_flag(EL1_TRACING_CONFIGURED); 271 } 272 EXPORT_SYMBOL_GPL(kvm_tracing_set_el1_configuration); 273