linux-kernel - [PATCH 3/5] KVM: nSVM: leave the guest mode prior to loading a nested state

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Date:   Mon,  3 May 2021 15:54:44 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
        64-BIT)), Jim Mattson <jmattson@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Joerg Roedel <joro@...tes.org>, Ingo Molnar <mingo@...hat.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Sean Christopherson <seanjc@...gle.com>,
        Cathy Avery <cavery@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH 3/5] KVM: nSVM: leave the guest mode prior to loading a nested state

This allows the KVM to load the nested state more than
once without warnings.

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/nested.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index a88c64e004c3..32400cba608d 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1309,12 +1309,15 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 	 * L2 registers if needed are moved from the current VMCB to VMCB02.
 	 */
 
+	if (is_guest_mode(vcpu))
+		svm_leave_nested(svm);
+	else
+		svm->nested.vmcb02.ptr->save = svm->vmcb01.ptr->save;
+
 	svm->nested.nested_run_pending =
 		!!(kvm_state->flags & KVM_STATE_NESTED_RUN_PENDING);
 
 	svm->nested.vmcb12_gpa = kvm_state->hdr.svm.vmcb_pa;
-	if (svm->current_vmcb == &svm->vmcb01)
-		svm->nested.vmcb02.ptr->save = svm->vmcb01.ptr->save;
 
 	svm->vmcb01.ptr->save.es = save->es;
 	svm->vmcb01.ptr->save.cs = save->cs;
-- 
2.26.2