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Peter Anvin" , linux-kernel@vger.kernel.org, Maxim Levitsky Subject: [PATCH v5 3/3] KVM: x86: add new nested vmexit tracepoints Date: Tue, 10 Sep 2024 16:03:50 -0400 Message-Id: <20240910200350.264245-4-mlevitsk@redhat.com> In-Reply-To: <20240910200350.264245-1-mlevitsk@redhat.com> References: <20240910200350.264245-1-mlevitsk@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Add 3 new tracepoints for nested VM exits which are intended to capture extra information to gain insights about the nested guest behavior. The new tracepoints are: - kvm_nested_msr - kvm_nested_hypercall These tracepoints capture extra register state to be able to know which MSR or which hypercall was done. - kvm_nested_page_fault This tracepoint allows to capture extra info about which host pagefault error code caused the nested page fault. Signed-off-by: Maxim Levitsky --- arch/x86/kvm/svm/nested.c | 22 +++++++++++ arch/x86/kvm/trace.h | 82 +++++++++++++++++++++++++++++++++++++-- arch/x86/kvm/vmx/nested.c | 27 +++++++++++++ arch/x86/kvm/x86.c | 3 ++ 4 files changed, 131 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 6f704c1037e51..2020307481553 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -38,6 +38,8 @@ static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu, { struct vcpu_svm *svm = to_svm(vcpu); struct vmcb *vmcb = svm->vmcb; + u64 host_error_code = vmcb->control.exit_info_1; + if (vmcb->control.exit_code != SVM_EXIT_NPF) { /* @@ -48,11 +50,15 @@ static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu, vmcb->control.exit_code_hi = 0; vmcb->control.exit_info_1 = (1ULL << 32); vmcb->control.exit_info_2 = fault->address; + host_error_code = 0; } vmcb->control.exit_info_1 &= ~0xffffffffULL; vmcb->control.exit_info_1 |= fault->error_code; + trace_kvm_nested_page_fault(fault->address, host_error_code, + fault->error_code); + nested_svm_vmexit(svm); } @@ -1126,6 +1132,22 @@ int nested_svm_vmexit(struct vcpu_svm *svm) vmcb12->control.exit_int_info_err, KVM_ISA_SVM); + /* Collect some info about nested VM exits */ + switch (vmcb12->control.exit_code) { + case SVM_EXIT_MSR: + trace_kvm_nested_msr(vmcb12->control.exit_info_1 == 1, + kvm_rcx_read(vcpu), + (vmcb12->save.rax & 0xFFFFFFFFull) | + (((u64)kvm_rdx_read(vcpu) << 32))); + break; + case SVM_EXIT_VMMCALL: + trace_kvm_nested_hypercall(vmcb12->save.rax, + kvm_rbx_read(vcpu), + kvm_rcx_read(vcpu), + kvm_rdx_read(vcpu)); + break; + } + kvm_vcpu_unmap(vcpu, &map, true); nested_svm_transition_tlb_flush(vcpu); diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h index 5a5b7757e8456..6074b4f85d5e2 100644 --- a/arch/x86/kvm/trace.h +++ b/arch/x86/kvm/trace.h @@ -613,7 +613,7 @@ TRACE_EVENT(kvm_pv_eoi, ); /* - * Tracepoint for nested VMRUN + * Tracepoint for nested VMRUN/VMENTER */ TRACE_EVENT(kvm_nested_vmenter, TP_PROTO(__u64 rip, __u64 vmcb, __u64 nested_rip, __u32 int_ctl, @@ -746,8 +746,84 @@ TRACE_EVENT(kvm_nested_intr_vmexit, TP_printk("rip: 0x%016llx", __entry->rip) ); + /* - * Tracepoint for nested #vmexit because of interrupt pending + * Tracepoint for nested guest MSR access. + */ +TRACE_EVENT(kvm_nested_msr, + TP_PROTO(bool write, u32 ecx, u64 data), + TP_ARGS(write, ecx, data), + + TP_STRUCT__entry( + __field( bool, write ) + __field( u32, ecx ) + __field( u64, data ) + ), + + TP_fast_assign( + __entry->write = write; + __entry->ecx = ecx; + __entry->data = data; + ), + + TP_printk("msr_%s %x = 0x%llx", + __entry->write ? "write" : "read", + __entry->ecx, __entry->data) +); + +/* + * Tracepoint for nested hypercalls, capturing generic info about the + * hypercall + */ + +TRACE_EVENT(kvm_nested_hypercall, + TP_PROTO(u64 rax, u64 rbx, u64 rcx, u64 rdx), + TP_ARGS(rax, rbx, rcx, rdx), + + TP_STRUCT__entry( + __field( u64, rax ) + __field( u64, rbx ) + __field( u64, rcx ) + __field( u64, rdx ) + ), + + TP_fast_assign( + __entry->rax = rax; + __entry->rbx = rbx; + __entry->rcx = rcx; + __entry->rdx = rdx; + ), + + TP_printk("rax 0x%llx rbx 0x%llx rcx 0x%llx rdx 0x%llx", + __entry->rax, __entry->rbx, __entry->rcx, __entry->rdx) +); + + +TRACE_EVENT(kvm_nested_page_fault, + TP_PROTO(u64 gpa, u64 host_error_code, u64 guest_error_code), + TP_ARGS(gpa, host_error_code, guest_error_code), + + TP_STRUCT__entry( + __field( u64, gpa ) + __field( u64, host_error_code ) + __field( u64, guest_errror_code ) + ), + + TP_fast_assign( + __entry->gpa = gpa; + __entry->host_error_code = host_error_code; + __entry->guest_errror_code = guest_error_code; + ), + + TP_printk("gpa 0x%llx host err 0x%llx guest err 0x%llx", + __entry->gpa, + __entry->host_error_code, + __entry->guest_errror_code) +); + + +/* + * Tracepoint for invlpga */ TRACE_EVENT(kvm_invlpga, TP_PROTO(__u64 rip, unsigned int asid, u64 address), @@ -770,7 +846,7 @@ TRACE_EVENT(kvm_invlpga, ); /* - * Tracepoint for nested #vmexit because of interrupt pending + * Tracepoint for skinit */ TRACE_EVENT(kvm_skinit, TP_PROTO(__u64 rip, __u32 slb), diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 2392a7ef254df..3881a02694fc2 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -454,6 +454,16 @@ static void nested_ept_inject_page_fault(struct kvm_vcpu *vcpu, */ nested_ept_invalidate_addr(vcpu, vmcs12->ept_pointer, fault->address); + + /* + * vmx_get_exit_qual() returns the original exit qualification, + * before it was overridden with exit qualification that + * is about to be injected to the guest. + */ + + trace_kvm_nested_page_fault(fault->address, + vmx_get_exit_qual(vcpu), + exit_qualification); } nested_vmx_vmexit(vcpu, vm_exit_reason, 0, exit_qualification); @@ -4985,6 +4995,23 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason, vmcs12->vm_exit_intr_error_code, KVM_ISA_VMX); + switch ((u16)vmcs12->vm_exit_reason) { + case EXIT_REASON_MSR_READ: + case EXIT_REASON_MSR_WRITE: + trace_kvm_nested_msr(vmcs12->vm_exit_reason == EXIT_REASON_MSR_WRITE, + kvm_rcx_read(vcpu), + (kvm_rax_read(vcpu) & 0xFFFFFFFFull) | + (((u64)kvm_rdx_read(vcpu)) << 32)); + break; + case EXIT_REASON_VMCALL: + trace_kvm_nested_hypercall(kvm_rax_read(vcpu), + kvm_rbx_read(vcpu), + kvm_rcx_read(vcpu), + kvm_rdx_read(vcpu)); + break; + + } + load_vmcs12_host_state(vcpu, vmcs12); return; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f72e5d89e942d..cb01cf2ad6ac9 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -14032,6 +14032,9 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_vmenter); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_vmexit); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_vmexit_inject); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_intr_vmexit); +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_hypercall); +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_page_fault); +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_msr); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_nested_vmenter_failed); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_invlpga); EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_skinit);