From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Maxim Levitsky <mlevitsk@redhat.com>
Subject: Re: [PATCH 5/7] KVM: nVMX: Reset eVMCS clean fields data from prepare_vmcs02()
Date: Wed, 12 May 2021 09:19:40 +0200 [thread overview]
Message-ID: <87bl9gwh9v.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <YJqxmJg0HajlfDa/@google.com>
Sean Christopherson <seanjc@google.com> writes:
> On Tue, May 11, 2021, Vitaly Kuznetsov wrote:
>> 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 lease 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.
>>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>> arch/x86/kvm/vmx/nested.c | 9 ++++++---
>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index 3257a2291693..1661e2e19560 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -2090,9 +2090,6 @@ void nested_sync_vmcs12_to_shadow(struct kvm_vcpu *vcpu)
>>
>> if (vmx->nested.hv_evmcs) {
>> copy_vmcs12_to_enlightened(vmx);
>> - /* All fields are clean */
>> - vmx->nested.hv_evmcs->hv_clean_fields |=
>> - HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL;
>> } else {
>> copy_vmcs12_to_shadow(vmx);
>> }
>
> Looks like this makes both paths single lines, i.e. the curly braces can be
> dropped.
>
Yea, I've noticed that but I wasn't exactly sure the benefit of removing
one line here overwhelms the pain of needing an extra step while doing
code archeology with 'git blame' :-) Will drop on v2.
>> @@ -2636,6 +2633,12 @@ 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);
>> +
>> + /* Mark all fields as clean so L1 hypervisor can set what's dirty */
>> + if (hv_evmcs)
>> + vmx->nested.hv_evmcs->hv_clean_fields |=
>> + HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL;
>> +
>> return 0;
>> }
>>
>> --
>> 2.30.2
>>
>
--
Vitaly
next prev parent reply other threads:[~2021-05-12 7:19 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 11:19 [PATCH 0/7] KVM: nVMX: Fixes for nested state migration when eVMCS is in use Vitaly Kuznetsov
2021-05-11 11:19 ` [PATCH 1/7] KVM: nVMX: Introduce nested_evmcs_is_used() Vitaly Kuznetsov
2021-05-11 11:19 ` [PATCH 2/7] KVM: nVMX: Release enlightened VMCS on VMCLEAR Vitaly Kuznetsov
2021-05-11 11:19 ` [PATCH 3/7] KVM: nVMX: Ignore 'hv_clean_fields' data when eVMCS data is copied in vmx_get_nested_state() Vitaly Kuznetsov
2021-05-11 16:37 ` Sean Christopherson
2021-05-12 7:14 ` Vitaly Kuznetsov
2021-05-11 11:19 ` [PATCH 4/7] KVM: nVMX: Force enlightened VMCS sync from nested_vmx_failValid() Vitaly Kuznetsov
2021-05-11 11:19 ` [PATCH 5/7] KVM: nVMX: Reset eVMCS clean fields data from prepare_vmcs02() Vitaly Kuznetsov
2021-05-11 16:32 ` Sean Christopherson
2021-05-12 7:19 ` Vitaly Kuznetsov [this message]
2021-05-11 11:19 ` [PATCH 6/7] KVM: nVMX: Request to sync eVMCS from VMCS12 after migration Vitaly Kuznetsov
2021-05-11 11:19 ` [PATCH 7/7] KVM: selftests: evmcs_test: Test that KVM_STATE_NESTED_EVMCS is never lost Vitaly Kuznetsov
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