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