From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 8727906fde6ea665b52e68ddc58833772537f40a upstream.
Reject KVM_SEV_INIT and KVM_SEV_ES_INIT if they are attempted after one
or more vCPUs have been created. KVM assumes a VM is tagged SEV/SEV-ES
prior to vCPU creation, e.g. init_vmcb() needs to mark the VMCB as SEV
enabled, and svm_create_vcpu() needs to allocate the VMSA. At best,
creating vCPUs before SEV/SEV-ES init will lead to unexpected errors
and/or behavior, and at worst it will crash the host, e.g.
sev_launch_update_vmsa() will dereference a null svm->vmsa pointer.
Fixes: 1654efcbc431 ("KVM: SVM: Add KVM_SEV_INIT command")
Fixes: ad73109ae7ec ("KVM: SVM: Provide support to launch and run an SEV-ES guest")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Brijesh Singh <brijesh.singh@xxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210331031936.2495277-4-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/svm/sev.c | 3 +++
1 file changed, 3 insertions(+)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -168,6 +168,9 @@ static int sev_guest_init(struct kvm *kv
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
int asid, ret;
+ if (kvm->created_vcpus)
+ return -EINVAL;
+
ret = -EBUSY;
if (unlikely(sev->active))
return ret;
