linux-kernel - [RFC PATCH 10/35] KVM: SVM: Cannot re-initialize the VMCB after shutdown with SEV-ES

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Message-Id: <79a8f9e03580f6cd45ffd02492fdf236fb14a88f.1600114548.git.thomas.lendacky@amd.com>
Date:   Mon, 14 Sep 2020 15:15:24 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [RFC PATCH 10/35] KVM: SVM: Cannot re-initialize the VMCB after shutdown with SEV-ES

From: Tom Lendacky <thomas.lendacky@....com>

When a SHUTDOWN VMEXIT is encountered, normally the VMCB is re-initialized
so that the guest can be re-launched. But when a guest is running as an
SEV-ES guest, the VMSA cannot be re-initialized because it has been
encrypted. For now, just return -EINVAL to prevent a possible attempt at
a guest reset.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kvm/svm/svm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 47fa2067609a..f9daa40b3cfc 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1953,6 +1953,13 @@ static int shutdown_interception(struct vcpu_svm *svm)
 {
 	struct kvm_run *kvm_run = svm->vcpu.run;
 
+	/*
+	 * The VM save area has already been encrypted so it
+	 * cannot be reinitialized - just terminate.
+	 */
+	if (sev_es_guest(svm->vcpu.kvm))
+		return -EINVAL;
+
 	/*
 	 * VMCB is undefined after a SHUTDOWN intercept
 	 * so reinitialize it.
-- 
2.28.0