From dc313385529f1a1fa20b06bb61239a31aca9d40f Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Wed, 26 May 2021 15:20:24 +0200 Subject: [PATCH] KVM: nVMX: Reset eVMCS clean fields data from prepare_vmcs02() When nested state migration happens during L1's execution, it is incorrect to modify eVMCS as it is L1 who 'owns' it at the moment. At least genuine Hyper-V seems to not be very happy when 'clean fields' data changes underneath it. 'Clean fields' data is used in KVM twice: by copy_enlightened_to_vmcs12() and prepare_vmcs02_rare() so we can reset it from prepare_vmcs02() instead. While at it, update a comment stating why exactly we need to reset 'hv_clean_fields' data from L0. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini Message-Id: <20210526132026.270394-10-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/nested.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index c73668b..2bdc9a2 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2059,14 +2059,10 @@ void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); - if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) { + if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) copy_vmcs12_to_enlightened(vmx); - /* All fields are clean */ - vmx->nested.hv_evmcs->hv_clean_fields |= - HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL; - } else { + else copy_vmcs12_to_shadow(vmx); - } vmx->nested.need_vmcs12_to_shadow_sync = false; } @@ -2616,6 +2612,17 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, kvm_rsp_write(vcpu, vmcs12->guest_rsp); kvm_rip_write(vcpu, vmcs12->guest_rip); + + /* + * It was observed that genuine Hyper-V running in L1 doesn't reset + * 'hv_clean_fields' by itself, it only sets the corresponding dirty + * bits when it changes a field in eVMCS. Mark all fields as clean + * here. + */ + if (evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) + vmx->nested.hv_evmcs->hv_clean_fields |= + HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL; + return 0; } -- 2.7.4