linux-kernel - [PATCH 3/6] KVM: SEV: Set sev_info.active after initial checks in sev_guest

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Date:   Tue,  9 Nov 2021 21:50:58 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Peter Gonda <pgonda@...gle.com>,
        Marc Orr <marcorr@...gle.com>,
        Nathan Tempelman <natet@...gle.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: [PATCH 3/6] KVM: SEV: Set sev_info.active after initial checks in sev_guest_init()

Set sev_info.active during SEV/SEV-ES activation before calling any code
that can potentially consume sev_info.es_active, e.g. set "active" and
"es_active" as a pair immediately after the initial sanity checks.  KVM
generally expects that es_active can be true if and only if active is
true, e.g. sev_asid_new() deliberately avoids sev_es_guest() so that it
doesn't get a false negative.  This will allow WARNing in sev_es_guest()
if the VM is tagged as SEV-ES but not SEV.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 6d14e2595c96..a869b11301df 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -229,7 +229,6 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
 static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 {
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
-	bool es_active = argp->id == KVM_SEV_ES_INIT;
 	int asid, ret;
 
 	if (kvm->created_vcpus)
@@ -239,7 +238,8 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	if (unlikely(sev->active))
 		return ret;
 
-	sev->es_active = es_active;
+	sev->active = true;
+	sev->es_active = argp->id == KVM_SEV_ES_INIT;
 	asid = sev_asid_new(sev);
 	if (asid < 0)
 		goto e_no_asid;
@@ -249,7 +249,6 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	if (ret)
 		goto e_free;
 
-	sev->active = true;
 	sev->asid = asid;
 	INIT_LIST_HEAD(&sev->regions_list);
 
@@ -260,6 +259,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	sev->asid = 0;
 e_no_asid:
 	sev->es_active = false;
+	sev->active = false;
 	return ret;
 }
 
-- 
2.34.0.rc0.344.g81b53c2807-goog