Messages in this thread | | | Subject | Re: [PATCH v5 7/7] KVM: SVM: hyper-v: Direct Virtual Flush support | From | Vineeth Pillai <> | Date | Tue, 15 Jun 2021 10:24:14 -0400 |
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Hi Vitaly, >> + >> +static inline void svm_hv_update_vp_id(struct vmcb *vmcb, >> + struct kvm_vcpu *vcpu) >> +{ >> + struct hv_enlightenments *hve = >> + (struct hv_enlightenments *)vmcb->control.reserved_sw; >> + >> + if (hve->hv_vp_id != to_hv_vcpu(vcpu)->vp_index) { >> + hve->hv_vp_id = to_hv_vcpu(vcpu)->vp_index; >> + vmcb_mark_dirty(vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS); >> + } > This blows up in testing when no Hyper-V context was created on a vCPU, > e.g. when running KVM selftests (to_hv_vcpu(vcpu) is NULL when no > Hyper-V emulation features were requested on a vCPU but > svm_hv_update_vp_id() is called unconditionally by svm_vcpu_run()). > > I'll be sending a patch to fix the immediate issue but I was wondering > why we need to call svm_hv_update_vp_id() from svm_vcpu_run() as VP > index is unlikely to change; we can probably just call it from > kvm_hv_set_msr() instead. Thanks a lot for catching this.
I think you are right, updating at kvm_hv_set_msr() makes sense. I was following the vmx logic where it also sets the vp_id in vmx_vcpu_run. But it calls a wrapper "kvm_hv_get_vpindex" which actually checks if hv_vcpu is not null before the assignment. I should have used that instead, my mistake. I will look a bit more into it and send out a patch for vmx and svm after little more investigation.
Thanks, Vineeth
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