From 6ccdbedd167c624697790c1c1edea7e9a04daf4d Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 30 Mar 2021 20:19:36 -0700 Subject: [PATCH] KVM: SVM: Do not allow SEV/SEV-ES initialization after vCPUs are created 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@vger.kernel.org Cc: Brijesh Singh Cc: Tom Lendacky Signed-off-by: Sean Christopherson Message-Id: <20210331031936.2495277-4-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/svm/sev.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index e3e04988fdab..16b10b9436dc 100644 --- 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 *kvm, struct kvm_sev_cmd *argp) 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;