KVM: SVM: Propagate error from snp_guest_req_init() to userspace

If snp_guest_req_init() fails, return the provided error code up the
stack to userspace, e.g. so that userspace can log that KVM_SEV_INIT2
failed, as opposed to some random operation later in VM setup failing
because SNP wasn't actually enabled for the VM.

Note, KVM itself doesn't consult the return value from __sev_guest_init(),
i.e. the fallout is purely that userspace may be confused.

Fixes: 88caf544c930 ("KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202410192220.MeTyHPxI-lkp@intel.com
Link: https://lore.kernel.org/r/20241031203214.1585751-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 0b851ef937f29761d421e4e266c232f3d2e63156..03c7db3b4cc37822d381fcbdd92ae9741b14f783 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -450,8 +450,11 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
                goto e_free;
 
        /* This needs to happen after SEV/SNP firmware initialization. */
-       if (vm_type == KVM_X86_SNP_VM && snp_guest_req_init(kvm))
-               goto e_free;
+       if (vm_type == KVM_X86_SNP_VM) {
+               ret = snp_guest_req_init(kvm);
+               if (ret)
+                       goto e_free;
+       }
 
        INIT_LIST_HEAD(&sev->regions_list);
        INIT_LIST_HEAD(&sev->mirror_vms);