1caab277bSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 256c7f5e7SAlex Bennée /* 356c7f5e7SAlex Bennée * Debug and Guest Debug support 456c7f5e7SAlex Bennée * 556c7f5e7SAlex Bennée * Copyright (C) 2015 - Linaro Ltd 656c7f5e7SAlex Bennée * Author: Alex Bennée <alex.bennee@linaro.org> 756c7f5e7SAlex Bennée */ 856c7f5e7SAlex Bennée 956c7f5e7SAlex Bennée #include <linux/kvm_host.h> 10eef8c85aSAlex Bennée #include <linux/hw_breakpoint.h> 1156c7f5e7SAlex Bennée 12337b99bfSAlex Bennée #include <asm/debug-monitors.h> 13337b99bfSAlex Bennée #include <asm/kvm_asm.h> 1456c7f5e7SAlex Bennée #include <asm/kvm_arm.h> 15337b99bfSAlex Bennée #include <asm/kvm_emulate.h> 16337b99bfSAlex Bennée 17eef8c85aSAlex Bennée #include "trace.h" 18eef8c85aSAlex Bennée 19337b99bfSAlex Bennée /* These are the bits of MDSCR_EL1 we may manipulate */ 20337b99bfSAlex Bennée #define MDSCR_EL1_DEBUG_MASK (DBG_MDSCR_SS | \ 21337b99bfSAlex Bennée DBG_MDSCR_KDE | \ 22337b99bfSAlex Bennée DBG_MDSCR_MDE) 2356c7f5e7SAlex Bennée 2456c7f5e7SAlex Bennée static DEFINE_PER_CPU(u32, mdcr_el2); 2556c7f5e7SAlex Bennée 2656c7f5e7SAlex Bennée /** 27337b99bfSAlex Bennée * save/restore_guest_debug_regs 28337b99bfSAlex Bennée * 29337b99bfSAlex Bennée * For some debug operations we need to tweak some guest registers. As 30337b99bfSAlex Bennée * a result we need to save the state of those registers before we 31337b99bfSAlex Bennée * make those modifications. 32337b99bfSAlex Bennée * 33337b99bfSAlex Bennée * Guest access to MDSCR_EL1 is trapped by the hypervisor and handled 34337b99bfSAlex Bennée * after we have restored the preserved value to the main context. 35337b99bfSAlex Bennée */ 36337b99bfSAlex Bennée static void save_guest_debug_regs(struct kvm_vcpu *vcpu) 37337b99bfSAlex Bennée { 388d404c4cSChristoffer Dall u64 val = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 398d404c4cSChristoffer Dall 408d404c4cSChristoffer Dall vcpu->arch.guest_debug_preserved.mdscr_el1 = val; 41eef8c85aSAlex Bennée 42eef8c85aSAlex Bennée trace_kvm_arm_set_dreg32("Saved MDSCR_EL1", 43eef8c85aSAlex Bennée vcpu->arch.guest_debug_preserved.mdscr_el1); 44337b99bfSAlex Bennée } 45337b99bfSAlex Bennée 46337b99bfSAlex Bennée static void restore_guest_debug_regs(struct kvm_vcpu *vcpu) 47337b99bfSAlex Bennée { 488d404c4cSChristoffer Dall u64 val = vcpu->arch.guest_debug_preserved.mdscr_el1; 498d404c4cSChristoffer Dall 508d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, val, MDSCR_EL1); 51eef8c85aSAlex Bennée 52eef8c85aSAlex Bennée trace_kvm_arm_set_dreg32("Restored MDSCR_EL1", 538d404c4cSChristoffer Dall vcpu_read_sys_reg(vcpu, MDSCR_EL1)); 54337b99bfSAlex Bennée } 55337b99bfSAlex Bennée 56337b99bfSAlex Bennée /** 5756c7f5e7SAlex Bennée * kvm_arm_init_debug - grab what we need for debug 5856c7f5e7SAlex Bennée * 5956c7f5e7SAlex Bennée * Currently the sole task of this function is to retrieve the initial 6056c7f5e7SAlex Bennée * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has 6156c7f5e7SAlex Bennée * presumably been set-up by some knowledgeable bootcode. 6256c7f5e7SAlex Bennée * 6356c7f5e7SAlex Bennée * It is called once per-cpu during CPU hyp initialisation. 6456c7f5e7SAlex Bennée */ 6556c7f5e7SAlex Bennée 6656c7f5e7SAlex Bennée void kvm_arm_init_debug(void) 6756c7f5e7SAlex Bennée { 687aa8d146SMarc Zyngier __this_cpu_write(mdcr_el2, kvm_call_hyp_ret(__kvm_get_mdcr_el2)); 6956c7f5e7SAlex Bennée } 7056c7f5e7SAlex Bennée 7156c7f5e7SAlex Bennée /** 72*263d6287SAlexandru Elisei * kvm_arm_setup_mdcr_el2 - configure vcpu mdcr_el2 value 73*263d6287SAlexandru Elisei * 74*263d6287SAlexandru Elisei * @vcpu: the vcpu pointer 75*263d6287SAlexandru Elisei * 76*263d6287SAlexandru Elisei * This ensures we will trap access to: 77*263d6287SAlexandru Elisei * - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR) 78*263d6287SAlexandru Elisei * - Debug ROM Address (MDCR_EL2_TDRA) 79*263d6287SAlexandru Elisei * - OS related registers (MDCR_EL2_TDOSA) 80*263d6287SAlexandru Elisei * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) 81*263d6287SAlexandru Elisei * - Self-hosted Trace Filter controls (MDCR_EL2_TTRF) 82*263d6287SAlexandru Elisei */ 83*263d6287SAlexandru Elisei static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu) 84*263d6287SAlexandru Elisei { 85*263d6287SAlexandru Elisei /* 86*263d6287SAlexandru Elisei * This also clears MDCR_EL2_E2PB_MASK to disable guest access 87*263d6287SAlexandru Elisei * to the profiling buffer. 88*263d6287SAlexandru Elisei */ 89*263d6287SAlexandru Elisei vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK; 90*263d6287SAlexandru Elisei vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | 91*263d6287SAlexandru Elisei MDCR_EL2_TPMS | 92*263d6287SAlexandru Elisei MDCR_EL2_TTRF | 93*263d6287SAlexandru Elisei MDCR_EL2_TPMCR | 94*263d6287SAlexandru Elisei MDCR_EL2_TDRA | 95*263d6287SAlexandru Elisei MDCR_EL2_TDOSA); 96*263d6287SAlexandru Elisei 97*263d6287SAlexandru Elisei /* Is the VM being debugged by userspace? */ 98*263d6287SAlexandru Elisei if (vcpu->guest_debug) 99*263d6287SAlexandru Elisei /* Route all software debug exceptions to EL2 */ 100*263d6287SAlexandru Elisei vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE; 101*263d6287SAlexandru Elisei 102*263d6287SAlexandru Elisei /* 103*263d6287SAlexandru Elisei * Trap debug register access when one of the following is true: 104*263d6287SAlexandru Elisei * - Userspace is using the hardware to debug the guest 105*263d6287SAlexandru Elisei * (KVM_GUESTDBG_USE_HW is set). 106*263d6287SAlexandru Elisei * - The guest is not using debug (KVM_ARM64_DEBUG_DIRTY is clear). 107*263d6287SAlexandru Elisei */ 108*263d6287SAlexandru Elisei if ((vcpu->guest_debug & KVM_GUESTDBG_USE_HW) || 109*263d6287SAlexandru Elisei !(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY)) 110*263d6287SAlexandru Elisei vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; 111*263d6287SAlexandru Elisei 112*263d6287SAlexandru Elisei trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2); 113*263d6287SAlexandru Elisei } 114*263d6287SAlexandru Elisei 115*263d6287SAlexandru Elisei /** 116*263d6287SAlexandru Elisei * kvm_arm_vcpu_init_debug - setup vcpu debug traps 117*263d6287SAlexandru Elisei * 118*263d6287SAlexandru Elisei * @vcpu: the vcpu pointer 119*263d6287SAlexandru Elisei * 120*263d6287SAlexandru Elisei * Set vcpu initial mdcr_el2 value. 121*263d6287SAlexandru Elisei */ 122*263d6287SAlexandru Elisei void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu) 123*263d6287SAlexandru Elisei { 124*263d6287SAlexandru Elisei preempt_disable(); 125*263d6287SAlexandru Elisei kvm_arm_setup_mdcr_el2(vcpu); 126*263d6287SAlexandru Elisei preempt_enable(); 127*263d6287SAlexandru Elisei } 128*263d6287SAlexandru Elisei 129*263d6287SAlexandru Elisei /** 13084e690bfSAlex Bennée * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state 13184e690bfSAlex Bennée */ 13284e690bfSAlex Bennée 13384e690bfSAlex Bennée void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) 13484e690bfSAlex Bennée { 13584e690bfSAlex Bennée vcpu->arch.debug_ptr = &vcpu->arch.vcpu_debug_state; 13684e690bfSAlex Bennée } 13784e690bfSAlex Bennée 13884e690bfSAlex Bennée /** 13956c7f5e7SAlex Bennée * kvm_arm_setup_debug - set up debug related stuff 14056c7f5e7SAlex Bennée * 14156c7f5e7SAlex Bennée * @vcpu: the vcpu pointer 14256c7f5e7SAlex Bennée * 14356c7f5e7SAlex Bennée * This is called before each entry into the hypervisor to setup any 144*263d6287SAlexandru Elisei * debug related registers. 14556c7f5e7SAlex Bennée * 14656c7f5e7SAlex Bennée * Additionally, KVM only traps guest accesses to the debug registers if 14756c7f5e7SAlex Bennée * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY 148fa89d31cSDave Martin * flag on vcpu->arch.flags). Since the guest must not interfere 14956c7f5e7SAlex Bennée * with the hardware state when debugging the guest, we must ensure that 15056c7f5e7SAlex Bennée * trapping is enabled whenever we are debugging the guest using the 15156c7f5e7SAlex Bennée * debug registers. 15256c7f5e7SAlex Bennée */ 15356c7f5e7SAlex Bennée 15456c7f5e7SAlex Bennée void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) 15556c7f5e7SAlex Bennée { 1564942dc66SAndrew Murray unsigned long mdscr, orig_mdcr_el2 = vcpu->arch.mdcr_el2; 15756c7f5e7SAlex Bennée 158eef8c85aSAlex Bennée trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug); 159eef8c85aSAlex Bennée 160*263d6287SAlexandru Elisei kvm_arm_setup_mdcr_el2(vcpu); 16156c7f5e7SAlex Bennée 162337b99bfSAlex Bennée /* Is Guest debugging in effect? */ 163337b99bfSAlex Bennée if (vcpu->guest_debug) { 164337b99bfSAlex Bennée /* Save guest debug state */ 165337b99bfSAlex Bennée save_guest_debug_regs(vcpu); 166337b99bfSAlex Bennée 167337b99bfSAlex Bennée /* 168337b99bfSAlex Bennée * Single Step (ARM ARM D2.12.3 The software step state 169337b99bfSAlex Bennée * machine) 170337b99bfSAlex Bennée * 171337b99bfSAlex Bennée * If we are doing Single Step we need to manipulate 172337b99bfSAlex Bennée * the guest's MDSCR_EL1.SS and PSTATE.SS. Once the 173337b99bfSAlex Bennée * step has occurred the hypervisor will trap the 174337b99bfSAlex Bennée * debug exception and we return to userspace. 175337b99bfSAlex Bennée * 176337b99bfSAlex Bennée * If the guest attempts to single step its userspace 177337b99bfSAlex Bennée * we would have to deal with a trapped exception 178337b99bfSAlex Bennée * while in the guest kernel. Because this would be 179337b99bfSAlex Bennée * hard to unwind we suppress the guest's ability to 180337b99bfSAlex Bennée * do so by masking MDSCR_EL.SS. 181337b99bfSAlex Bennée * 182337b99bfSAlex Bennée * This confuses guest debuggers which use 183337b99bfSAlex Bennée * single-step behind the scenes but everything 184337b99bfSAlex Bennée * returns to normal once the host is no longer 185337b99bfSAlex Bennée * debugging the system. 186337b99bfSAlex Bennée */ 187337b99bfSAlex Bennée if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { 188337b99bfSAlex Bennée *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; 1898d404c4cSChristoffer Dall mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 1908d404c4cSChristoffer Dall mdscr |= DBG_MDSCR_SS; 1918d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); 192337b99bfSAlex Bennée } else { 1938d404c4cSChristoffer Dall mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 1948d404c4cSChristoffer Dall mdscr &= ~DBG_MDSCR_SS; 1958d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); 196337b99bfSAlex Bennée } 197834bf887SAlex Bennée 198eef8c85aSAlex Bennée trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu)); 199eef8c85aSAlex Bennée 200834bf887SAlex Bennée /* 201834bf887SAlex Bennée * HW Breakpoints and watchpoints 202834bf887SAlex Bennée * 203834bf887SAlex Bennée * We simply switch the debug_ptr to point to our new 204834bf887SAlex Bennée * external_debug_state which has been populated by the 205834bf887SAlex Bennée * debug ioctl. The existing KVM_ARM64_DEBUG_DIRTY 206834bf887SAlex Bennée * mechanism ensures the registers are updated on the 207834bf887SAlex Bennée * world switch. 208834bf887SAlex Bennée */ 209834bf887SAlex Bennée if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { 210834bf887SAlex Bennée /* Enable breakpoints/watchpoints */ 2118d404c4cSChristoffer Dall mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); 2128d404c4cSChristoffer Dall mdscr |= DBG_MDSCR_MDE; 2138d404c4cSChristoffer Dall vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1); 214834bf887SAlex Bennée 215834bf887SAlex Bennée vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state; 216fa89d31cSDave Martin vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY; 217eef8c85aSAlex Bennée 218eef8c85aSAlex Bennée trace_kvm_arm_set_regset("BKPTS", get_num_brps(), 219eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bcr[0], 220eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bvr[0]); 221eef8c85aSAlex Bennée 222eef8c85aSAlex Bennée trace_kvm_arm_set_regset("WAPTS", get_num_wrps(), 223eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wcr[0], 224eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wvr[0]); 225337b99bfSAlex Bennée } 22656c7f5e7SAlex Bennée } 22756c7f5e7SAlex Bennée 228834bf887SAlex Bennée BUG_ON(!vcpu->guest_debug && 229834bf887SAlex Bennée vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state); 230834bf887SAlex Bennée 23154ceb1bcSChristoffer Dall /* If KDE or MDE are set, perform a full save/restore cycle. */ 2328d404c4cSChristoffer Dall if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE)) 233fa89d31cSDave Martin vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY; 23454ceb1bcSChristoffer Dall 2354942dc66SAndrew Murray /* Write mdcr_el2 changes since vcpu_load on VHE systems */ 2364942dc66SAndrew Murray if (has_vhe() && orig_mdcr_el2 != vcpu->arch.mdcr_el2) 2374942dc66SAndrew Murray write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); 2384942dc66SAndrew Murray 2398d404c4cSChristoffer Dall trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1)); 240834bf887SAlex Bennée } 241834bf887SAlex Bennée 24256c7f5e7SAlex Bennée void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) 24356c7f5e7SAlex Bennée { 244eef8c85aSAlex Bennée trace_kvm_arm_clear_debug(vcpu->guest_debug); 245eef8c85aSAlex Bennée 246834bf887SAlex Bennée if (vcpu->guest_debug) { 247337b99bfSAlex Bennée restore_guest_debug_regs(vcpu); 248834bf887SAlex Bennée 249834bf887SAlex Bennée /* 250834bf887SAlex Bennée * If we were using HW debug we need to restore the 251834bf887SAlex Bennée * debug_ptr to the guest debug state. 252834bf887SAlex Bennée */ 253eef8c85aSAlex Bennée if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) { 254834bf887SAlex Bennée kvm_arm_reset_debug_ptr(vcpu); 255834bf887SAlex Bennée 256eef8c85aSAlex Bennée trace_kvm_arm_set_regset("BKPTS", get_num_brps(), 257eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bcr[0], 258eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_bvr[0]); 259eef8c85aSAlex Bennée 260eef8c85aSAlex Bennée trace_kvm_arm_set_regset("WAPTS", get_num_wrps(), 261eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wcr[0], 262eef8c85aSAlex Bennée &vcpu->arch.debug_ptr->dbg_wvr[0]); 263eef8c85aSAlex Bennée } 264834bf887SAlex Bennée } 26556c7f5e7SAlex Bennée } 266