From 45c3af974ec6c22d7392e15eb5d755e3c0079bd1 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Sun, 25 Nov 2018 18:45:35 +0100 Subject: KVM: x86: Trace changes to active TSC offset regardless if vCPU in guest-mode For some reason, kvm_x86_ops->write_l1_tsc_offset() skipped trace of change to active TSC offset in case vCPU is in guest-mode. This patch changes write_l1_tsc_offset() behavior to trace any change to active TSC offset to aid debugging. The VMX code is changed to look more similar to SVM, which is in my opinion nicer. Based on a patch by Liran Alon. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm.c | 9 +++++---- arch/x86/kvm/vmx.c | 34 +++++++++++++++++----------------- 2 files changed, 22 insertions(+), 21 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index cc6467b35a85..d7fec9f4af43 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1456,10 +1456,11 @@ static u64 svm_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) g_tsc_offset = svm->vmcb->control.tsc_offset - svm->nested.hsave->control.tsc_offset; svm->nested.hsave->control.tsc_offset = offset; - } else - trace_kvm_write_tsc_offset(vcpu->vcpu_id, - svm->vmcb->control.tsc_offset, - offset); + } + + trace_kvm_write_tsc_offset(vcpu->vcpu_id, + svm->vmcb->control.tsc_offset - g_tsc_offset, + offset); svm->vmcb->control.tsc_offset = offset + g_tsc_offset; diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 02edd9960e9d..9e2438e3c646 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3466,24 +3466,24 @@ static u64 vmx_read_l1_tsc_offset(struct kvm_vcpu *vcpu) static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) { - u64 active_offset = offset; - if (is_guest_mode(vcpu)) { - /* - * We're here if L1 chose not to trap WRMSR to TSC. According - * to the spec, this should set L1's TSC; The offset that L1 - * set for L2 remains unchanged, and still needs to be added - * to the newly set TSC to get L2's TSC. - */ - struct vmcs12 *vmcs12 = get_vmcs12(vcpu); - if (nested_cpu_has(vmcs12, CPU_BASED_USE_TSC_OFFSETING)) - active_offset += vmcs12->tsc_offset; - } else { - trace_kvm_write_tsc_offset(vcpu->vcpu_id, - vmcs_read64(TSC_OFFSET), offset); - } + struct vmcs12 *vmcs12 = get_vmcs12(vcpu); + u64 g_tsc_offset = 0; + + /* + * We're here if L1 chose not to trap WRMSR to TSC. According + * to the spec, this should set L1's TSC; The offset that L1 + * set for L2 remains unchanged, and still needs to be added + * to the newly set TSC to get L2's TSC. + */ + if (is_guest_mode(vcpu) && + (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETING)) + g_tsc_offset = vmcs12->tsc_offset; - vmcs_write64(TSC_OFFSET, active_offset); - return active_offset; + trace_kvm_write_tsc_offset(vcpu->vcpu_id, + vcpu->arch.tsc_offset - g_tsc_offset, + offset); + vmcs_write64(TSC_OFFSET, offset + g_tsc_offset); + return offset + g_tsc_offset; } /* -- cgit