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KVM: SVM: Use online_vcpus, not created_vcpus, to iterate over vCPUs

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Use the kvm_for_each_vcpu() helper to iterate over vCPUs when encrypting
VMSAs for SEV, which effectively switches to use online_vcpus instead of
created_vcpus.  This fixes a possible null-pointer dereference as
created_vcpus does not guarantee a vCPU exists, since it is updated at
the very beginning of KVM_CREATE_VCPU.  created_vcpus exists to allow the
bulk of vCPU creation to run in parallel, while still correctly
restricting the max number of max vCPUs.

Fixes: ad73109ae7ec ("KVM: SVM: Provide support to launch and run an SEV-ES guest")
Cc: stable@vger.kernel.org
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210331031936.2495277-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-03-30 20:19:34 -07:00 committed by Paolo Bonzini
parent 8f8f52a45d
commit c36b16d29f
1 changed files with 3 additions and 2 deletions
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5
arch/x86/kvm/svm/sev.c
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@ -564,6 +564,7 @@ static int sev_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
struct sev_data_launch_update_vmsa *vmsa;
struct kvm_vcpu *vcpu;
int i, ret;
if (!sev_es_guest(kvm))
@ -573,8 +574,8 @@ static int sev_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp)
if (!vmsa)
return -ENOMEM;
for (i = 0; i < kvm->created_vcpus; i++) {
struct vcpu_svm *svm = to_svm(kvm->vcpus[i]);
kvm_for_each_vcpu(i, vcpu, kvm) {
struct vcpu_svm *svm = to_svm(vcpu);
/* Perform some pre-encryption checks against the VMSA */
ret = sev_es_sync_vmsa(svm);