From: Sean Christopherson Date: Tue, 6 Apr 2021 17:18:08 +0000 (-0700) Subject: KVM: SVM: Don't set current_vmcb->cpu when switching vmcb X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=17e5e964eee05a3ee434cf0958ecce741a6874b1;p=linux.git KVM: SVM: Don't set current_vmcb->cpu when switching vmcb Do not update the new vmcb's last-run cpu when switching to a different vmcb. If the vCPU is migrated between its last run and a vmcb switch, e.g. for nested VM-Exit, then setting the cpu without marking the vmcb dirty will lead to KVM running the vCPU on a different physical cpu with stale clean bit settings. vcpu->cpu current_vmcb->cpu hardware pre_svm_run() cpu0 cpu0 cpu0,clean kvm_arch_vcpu_load() cpu1 cpu0 cpu0,clean svm_switch_vmcb() cpu1 cpu1 cpu0,clean pre_svm_run() cpu1 cpu1 kaboom Simply delete the offending code; unlike VMX, which needs to update the cpu at switch time due to the need to do VMPTRLD, SVM only cares about which cpu last ran the vCPU. Fixes: af18fa775d07 ("KVM: nSVM: Track the physical cpu of the vmcb vmrun through the vmcb") Cc: Cathy Avery Signed-off-by: Sean Christopherson Message-Id: <20210406171811.4043363-2-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 4fc1f16505db1..04ef49d3862d3 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1311,14 +1311,6 @@ void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb) svm->current_vmcb = target_vmcb; svm->vmcb = target_vmcb->ptr; svm->vmcb_pa = target_vmcb->pa; - - /* - * Track the physical CPU the target_vmcb is running on - * in order to mark the VMCB dirty if the cpu changes at - * its next vmrun. - */ - - svm->current_vmcb->cpu = svm->vcpu.cpu; } static int svm_create_vcpu(struct kvm_vcpu *vcpu)