Re: [PATCH RFC v9 29/51] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_START command

Peter Gonda
2023-06-12T17:08:35Z

> +
> +static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> + struct sev_data_snp_launch_start start = {0};
> + struct kvm_sev_snp_launch_start params;
> + int rc;
> +
> + if (!sev_snp_guest(kvm))
> + return -ENOTTY;
> +
> + if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data, sizeof(params)))
> + return -EFAULT;
> +
> + sev->snp_context = snp_context_create(kvm, argp);
> + if (!sev->snp_context)
> + return -ENOTTY;

I commented on a previous series but I think the bug is still here. I
think users can repeatedly call KVM_SEV_SNP_LAUNCH_START to have KVM
keep allocating more snp_contexts above.

Should we check if the VM already has a |snp_context| and error out if so?

>
> +
> + start.gctx_paddr = __psp_pa(sev->snp_context);
> + start.policy = params.policy;
> + memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw));
> + rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error);
> + if (rc)
> + goto e_free_context;
> +
> + sev->fd = argp->sev_fd;
> + rc = snp_bind_asid(kvm, &argp->error);
> + if (rc)
> + goto e_free_context;
> +
> + return 0;
> +
> +e_free_context:
> + snp_decommission_context(kvm);
> +
> + return rc;
> +}
> +