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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	Sean Christopherson <seanjc@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>,
	Maxim Levitsky <mlevitsk@redhat.com>
Subject: [PATCH 2/7] KVM: nVMX: Release enlightened VMCS on VMCLEAR
Date: Tue, 11 May 2021 13:19:51 +0200	[thread overview]
Message-ID: <20210511111956.1555830-3-vkuznets@redhat.com> (raw)
In-Reply-To: <20210511111956.1555830-1-vkuznets@redhat.com>

Unlike VMREAD/VMWRITE/VMPTRLD, VMCLEAR is a valid instruction when
enlightened VMCS is in use. TLFS has the following brief description:
"The L1 hypervisor can execute a VMCLEAR instruction to transition an
enlightened VMCS from the active to the non-active state". Normally,
this change can be ignored as unmapping active eVMCS can be postponed
until the next VMLAUNCH instruction but in case nested state is migrated
may result in its synchronization with VMCS12 and this is incorrect:
L1 hypervisor is free to reuse inactive eVMCS memory for something else.

Inactive eVMCS after VMCLEAR can just be unmapped.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
 arch/x86/kvm/vmx/nested.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3080e00c8f90..ea2869d8b823 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5008,6 +5008,8 @@ static int handle_vmclear(struct kvm_vcpu *vcpu)
 				     vmptr + offsetof(struct vmcs12,
 				     &zero, sizeof(zero));
+	} else if (vmx->nested.hv_evmcs && vmptr == vmx->nested.hv_evmcs_vmptr) {
+		nested_release_evmcs(vcpu);
 	return nested_vmx_succeed(vcpu);

  parent reply	other threads:[~2021-05-11 11:20 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 ` Vitaly Kuznetsov [this message]
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
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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