From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- arch/arm64/kvm/debug.c | 293 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 293 insertions(+) create mode 100644 arch/arm64/kvm/debug.c (limited to 'arch/arm64/kvm/debug.c') diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c new file mode 100644 index 000000000..f4d7b1204 --- /dev/null +++ b/arch/arm64/kvm/debug.c @@ -0,0 +1,293 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Debug and Guest Debug support + * + * Copyright (C) 2015 - Linaro Ltd + * Authors: Alex Bennée + * Oliver Upton + */ + +#include +#include + +#include +#include +#include +#include +#include + +static int cpu_has_spe(u64 dfr0) +{ + return cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_PMSVer_SHIFT) && + !(read_sysreg_s(SYS_PMBIDR_EL1) & PMBIDR_EL1_P); +} + +/** + * kvm_arm_setup_mdcr_el2 - configure vcpu mdcr_el2 value + * + * @vcpu: the vcpu pointer + * + * This ensures we will trap access to: + * - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR) + * - Debug ROM Address (MDCR_EL2_TDRA) + * - OS related registers (MDCR_EL2_TDOSA) + * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) + * - Self-hosted Trace Filter controls (MDCR_EL2_TTRF) + * - Self-hosted Trace (MDCR_EL2_TTRF/MDCR_EL2_E2TB) + */ +static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu) +{ + preempt_disable(); + + /* + * This also clears MDCR_EL2_E2PB_MASK and MDCR_EL2_E2TB_MASK + * to disable guest access to the profiling and trace buffers + */ + vcpu->arch.mdcr_el2 = FIELD_PREP(MDCR_EL2_HPMN, + *host_data_ptr(nr_event_counters)); + vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | + MDCR_EL2_TPMS | + MDCR_EL2_TTRF | + MDCR_EL2_TPMCR | + MDCR_EL2_TDRA | + MDCR_EL2_TDOSA); + + /* Is the VM being debugged by userspace? */ + if (vcpu->guest_debug) + /* Route all software debug exceptions to EL2 */ + vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE; + + /* + * Trap debug registers if the guest doesn't have ownership of them. + */ + if (!kvm_guest_owns_debug_regs(vcpu)) + vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA; + + if (vcpu_has_nv(vcpu)) + kvm_nested_setup_mdcr_el2(vcpu); + + /* Write MDCR_EL2 directly if we're already at EL2 */ + if (has_vhe()) + write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2); + + preempt_enable(); +} + +void kvm_init_host_debug_data(void) +{ + u64 dfr0 = read_sysreg(id_aa64dfr0_el1); + unsigned int pmuver = cpuid_feature_extract_unsigned_field(dfr0, + ID_AA64DFR0_EL1_PMUVer_SHIFT); + + if (pmuv3_implemented(pmuver)) + *host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N, + read_sysreg(pmcr_el0)); + + *host_data_ptr(debug_brps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr0); + *host_data_ptr(debug_wrps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr0); + + if (cpu_has_spe(dfr0)) + host_data_set_flag(HAS_SPE); + + if (has_vhe()) + return; + + /* Check if we have BRBE implemented and available at the host */ + if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_BRBE_SHIFT)) + host_data_set_flag(HAS_BRBE); + + if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceFilt_SHIFT)) { + /* Force disable trace in protected mode in case of no TRBE */ + if (is_protected_kvm_enabled()) + host_data_set_flag(EL1_TRACING_CONFIGURED); + + if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffer_SHIFT) && + !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P)) + host_data_set_flag(HAS_TRBE); + } +} + +void kvm_debug_init_vhe(void) +{ + /* Clear PMSCR_EL1.E{0,1}SPE which reset to UNKNOWN values. */ + if (host_data_test_flag(HAS_SPE)) + write_sysreg_el1(0, SYS_PMSCR); +} + +/* + * Configures the 'external' MDSCR_EL1 value for the guest, i.e. when the host + * has taken over MDSCR_EL1. + * + * - Userspace is single-stepping the guest, and MDSCR_EL1.SS is forced to 1. + * + * - Userspace is using the breakpoint/watchpoint registers to debug the + * guest, and MDSCR_EL1.MDE is forced to 1. + * + * - The guest has enabled the OS Lock, and KVM is forcing MDSCR_EL1.MDE to 0, + * masking all debug exceptions affected by the OS Lock. + */ +static void setup_external_mdscr(struct kvm_vcpu *vcpu) +{ + /* + * Use the guest's MDSCR_EL1 as a starting point, since there are + * several other features controlled by MDSCR_EL1 that are not relevant + * to the host. + * + * Clear the bits that KVM may use which also satisfies emulation of + * the OS Lock as MDSCR_EL1.MDE is cleared. + */ + u64 mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1) & ~(MDSCR_EL1_SS | + MDSCR_EL1_MDE | + MDSCR_EL1_KDE); + + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) + mdscr |= MDSCR_EL1_SS; + + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) + mdscr |= MDSCR_EL1_MDE | MDSCR_EL1_KDE; + + vcpu->arch.external_mdscr_el1 = mdscr; +} + +void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu) +{ + u64 mdscr; + + /* Must be called before kvm_vcpu_load_vhe() */ + KVM_BUG_ON(vcpu_get_flag(vcpu, SYSREGS_ON_CPU), vcpu->kvm); + + if (has_vhe()) + *host_data_ptr(host_debug_state.mdcr_el2) = read_sysreg(mdcr_el2); + + /* + * Determine which of the possible debug states we're in: + * + * - VCPU_DEBUG_HOST_OWNED: KVM has taken ownership of the guest's + * breakpoint/watchpoint registers, or needs to use MDSCR_EL1 to do + * software step or emulate the effects of the OS Lock being enabled. + * + * - VCPU_DEBUG_GUEST_OWNED: The guest has debug exceptions enabled, and + * the breakpoint/watchpoint registers need to be loaded eagerly. + * + * - VCPU_DEBUG_FREE: Neither of the above apply, no breakpoint/watchpoint + * context needs to be loaded on the CPU. + */ + if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) { + vcpu->arch.debug_owner = VCPU_DEBUG_HOST_OWNED; + setup_external_mdscr(vcpu); + + /* + * Steal the guest's single-step state machine if userspace wants + * single-step the guest. + */ + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + if (*vcpu_cpsr(vcpu) & DBG_SPSR_SS) + vcpu_clear_flag(vcpu, GUEST_SS_ACTIVE_PENDING); + else + vcpu_set_flag(vcpu, GUEST_SS_ACTIVE_PENDING); + + if (!vcpu_get_flag(vcpu, HOST_SS_ACTIVE_PENDING)) + *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; + else + *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; + } + } else { + mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1); + + if (mdscr & (MDSCR_EL1_KDE | MDSCR_EL1_MDE)) + vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED; + else + vcpu->arch.debug_owner = VCPU_DEBUG_FREE; + } + + kvm_arm_setup_mdcr_el2(vcpu); +} + +void kvm_vcpu_put_debug(struct kvm_vcpu *vcpu) +{ + if (has_vhe()) + write_sysreg(*host_data_ptr(host_debug_state.mdcr_el2), mdcr_el2); + + if (likely(!(vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP))) + return; + + /* + * Save the host's software step state and restore the guest's before + * potentially returning to userspace. + */ + if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS)) + vcpu_set_flag(vcpu, HOST_SS_ACTIVE_PENDING); + else + vcpu_clear_flag(vcpu, HOST_SS_ACTIVE_PENDING); + + if (vcpu_get_flag(vcpu, GUEST_SS_ACTIVE_PENDING)) + *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; + else + *vcpu_cpsr(vcpu) |= DBG_SPSR_SS; +} + +/* + * Updates ownership of the debug registers after a trapped guest access to a + * breakpoint/watchpoint register. Host ownership of the debug registers is of + * strictly higher priority, and it is the responsibility of the VMM to emulate + * guest debug exceptions in this configuration. + */ +void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu) +{ + if (kvm_host_owns_debug_regs(vcpu)) + return; + + vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED; + kvm_arm_setup_mdcr_el2(vcpu); +} + +void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val) +{ + if (val & OSLAR_EL1_OSLK) + __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, |=, OSLSR_EL1_OSLK); + else + __vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, &=, ~OSLSR_EL1_OSLK); + + preempt_disable(); + kvm_arch_vcpu_put(vcpu); + kvm_arch_vcpu_load(vcpu, smp_processor_id()); + preempt_enable(); +} + +static bool skip_trbe_access(bool skip_condition) +{ + return (WARN_ON_ONCE(preemptible()) || skip_condition || + is_protected_kvm_enabled() || !is_kvm_arm_initialised()); +} + +void kvm_enable_trbe(void) +{ + if (!skip_trbe_access(has_vhe())) + host_data_set_flag(TRBE_ENABLED); +} +EXPORT_SYMBOL_GPL(kvm_enable_trbe); + +void kvm_disable_trbe(void) +{ + if (!skip_trbe_access(has_vhe())) + host_data_clear_flag(TRBE_ENABLED); +} +EXPORT_SYMBOL_GPL(kvm_disable_trbe); + +void kvm_tracing_set_el1_configuration(u64 trfcr_while_in_guest) +{ + if (skip_trbe_access(false)) + return; + + if (has_vhe()) { + write_sysreg_s(trfcr_while_in_guest, SYS_TRFCR_EL12); + return; + } + + *host_data_ptr(trfcr_while_in_guest) = trfcr_while_in_guest; + if (read_sysreg_s(SYS_TRFCR_EL1) != trfcr_while_in_guest) + host_data_set_flag(EL1_TRACING_CONFIGURED); + else + host_data_clear_flag(EL1_TRACING_CONFIGURED); +} +EXPORT_SYMBOL_GPL(kvm_tracing_set_el1_configuration); -- cgit v1.3.1