This parameter will be used by VMX and SVM code to force interception of a set of exceptions, given by a bitmask for guest debug and/or kvm debug. This is based on an idea first shown here: https://patchwork.kernel.org/project/kvm/patch/20160301192822.GD22677@xxxxxxx/ CC: Borislav Petkov <bp@xxxxxxx> Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> --- arch/x86/include/asm/kvm_host.h | 7 +++++++ arch/x86/kvm/x86.c | 9 +++++++++ arch/x86/kvm/x86.h | 5 +++++ 3 files changed, 21 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 428ab1cc7dd34..fa498612839a0 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1168,6 +1168,13 @@ struct kvm_arch { struct kvm_pmu_event_filter __rcu *pmu_event_filter; struct task_struct *nx_lpage_recovery_thread; + /* + * Bitmask of exceptions that KVM will intercept + * and forward to the guest, even if that is not needed + * for normal operation. Debug feature. + */ + u32 force_intercept_exceptions_bitmask; + #ifdef CONFIG_X86_64 /* * Whether the TDP MMU is enabled for this VM. This contains a diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 63d84c373e465..202c34697852f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -193,6 +193,13 @@ module_param(enable_pmu, bool, 0444); bool __read_mostly eager_page_split = true; module_param(eager_page_split, bool, 0644); +/* + * force_intercept_exceptions_mask is a writable param and its value + * is snapshotted when a VM is created + */ +static uint force_intercept_exceptions_mask; +module_param(force_intercept_exceptions_mask, uint, S_IRUGO | S_IWUSR); + /* * Restoring the host value for MSRs that are only consumed when running in * usermode, e.g. SYSCALL MSRs and TSC_AUX, can be deferred until the CPU @@ -11646,6 +11653,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); kvm->arch.guest_can_read_msr_platform_info = true; + kvm->arch.force_intercept_exceptions_bitmask = force_intercept_exceptions_mask; #if IS_ENABLED(CONFIG_HYPERV) spin_lock_init(&kvm->arch.hv_root_tdp_lock); @@ -12886,6 +12894,7 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size, } EXPORT_SYMBOL_GPL(kvm_sev_es_string_io); + EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_entry); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index e9b303b21f173..34f96f483c7e5 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -91,6 +91,11 @@ static inline bool kvm_exception_is_soft(unsigned int nr) return (nr == BP_VECTOR) || (nr == OF_VECTOR); } +static inline bool kvm_is_exception_force_intercepted(struct kvm *kvm, int exception) +{ + return kvm->arch.force_intercept_exceptions_bitmask & BIT(exception); +} + static inline bool is_protmode(struct kvm_vcpu *vcpu) { return kvm_read_cr0_bits(vcpu, X86_CR0_PE); -- 2.26.3
