From patchwork Wed Jul 20 09:22:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 12923745 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D94CCCA486 for ; Wed, 20 Jul 2022 09:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238163AbiGTJXg (ORCPT ); Wed, 20 Jul 2022 05:23:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232409AbiGTJXd (ORCPT ); Wed, 20 Jul 2022 05:23:33 -0400 Received: from out0.migadu.com (out0.migadu.com [IPv6:2001:41d0:2:267::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31E12474D3 for ; Wed, 20 Jul 2022 02:23:32 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1658309010; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TPC65f+/SpKvE1qabwWtUjvFps/u8ooCGD/VYWnw8co=; b=I/71aFwYyNmnMBIh+PDUiVtVlTAnj7MQecccPvdHsgM1u81u0LbwnsLiOARWufwAdTFwmH ejF+sNZ65HjDRWGVWUtgnO0hesimHZYLJqCvzNErJhpjDbvysbFtt+hRFDkkOJW5MkZ2ud OlJM8Bfxc/PQyIyhZEqU62iuq7k9vbM= From: Oliver Upton To: kvm@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Oliver Upton Subject: [PATCH v3 5/6] KVM: Actually create debugfs in kvm_create_vm() Date: Wed, 20 Jul 2022 09:22:51 +0000 Message-Id: <20220720092259.3491733-6-oliver.upton@linux.dev> In-Reply-To: <20220720092259.3491733-1-oliver.upton@linux.dev> References: <20220720092259.3491733-1-oliver.upton@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Oliver Upton Doing debugfs creation after vm creation leaves things in a quasi-initialized state for a while. This is further complicated by the fact that we tear down debugfs from kvm_destroy_vm(). Align debugfs and stats init/destroy with the vm init/destroy pattern to avoid any headaches. Note the fix for a benign mistake in error handling for calls to kvm_arch_create_vm_debugfs() rolled in. Since all implementations of the function return 0 unconditionally it isn't actually a bug at the moment. Lastly, tear down debugfs/stats data in the kvm_create_vm_debugfs() error path. Previously it was safe to assume that kvm_destroy_vm() would take out the garbage, that is no longer the case. Signed-off-by: Oliver Upton Reviewed-by: Sean Christopherson --- virt/kvm/kvm_main.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 insertions(+), 17 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1e7f780a357b..609f49a133f8 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1028,7 +1028,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname) char dir_name[ITOA_MAX_LEN * 2]; struct kvm_stat_data *stat_data; const struct _kvm_stats_desc *pdesc; - int i, ret; + int i, ret = -ENOMEM; int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc + kvm_vcpu_stats_header.num_desc; @@ -1054,13 +1054,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname) sizeof(*kvm->debugfs_stat_data), GFP_KERNEL_ACCOUNT); if (!kvm->debugfs_stat_data) - return -ENOMEM; + goto out_err; for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) { pdesc = &kvm_vm_stats_desc[i]; stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT); if (!stat_data) - return -ENOMEM; + goto out_err; stat_data->kvm = kvm; stat_data->desc = pdesc; @@ -1075,7 +1075,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname) pdesc = &kvm_vcpu_stats_desc[i]; stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT); if (!stat_data) - return -ENOMEM; + goto out_err; stat_data->kvm = kvm; stat_data->desc = pdesc; @@ -1087,12 +1087,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname) } ret = kvm_arch_create_vm_debugfs(kvm); - if (ret) { - kvm_destroy_vm_debugfs(kvm); - return i; - } + if (ret) + goto out_err; return 0; +out_err: + kvm_destroy_vm_debugfs(kvm); + return ret; } /* @@ -1123,7 +1124,7 @@ int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) return 0; } -static struct kvm *kvm_create_vm(unsigned long type) +static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) { struct kvm *kvm = kvm_arch_alloc_vm(); struct kvm_memslots *slots; @@ -1212,7 +1213,7 @@ static struct kvm *kvm_create_vm(unsigned long type) r = kvm_arch_post_init_vm(kvm); if (r) - goto out_err; + goto out_err_mmu_notifier; mutex_lock(&kvm_lock); list_add(&kvm->vm_list, &vm_list); @@ -1228,12 +1229,18 @@ static struct kvm *kvm_create_vm(unsigned long type) */ if (!try_module_get(kvm_chardev_ops.owner)) { r = -ENODEV; - goto out_err; + goto out_err_mmu_notifier; } + r = kvm_create_vm_debugfs(kvm, fdname); + if (r) + goto out_err; + return kvm; out_err: + module_put(kvm_chardev_ops.owner); +out_err_mmu_notifier: #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER) if (kvm->mmu_notifier.ops) mmu_notifier_unregister(&kvm->mmu_notifier, current->mm); @@ -4900,7 +4907,7 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) snprintf(fdname, sizeof(fdname), "%d", fd); - kvm = kvm_create_vm(type); + kvm = kvm_create_vm(type, fdname); if (IS_ERR(kvm)) { r = PTR_ERR(kvm); goto put_fd; @@ -4923,11 +4930,6 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) * cases it will be called by the final fput(file) and will take * care of doing kvm_put_kvm(kvm). */ - if (kvm_create_vm_debugfs(kvm, fdname) < 0) { - fput(file); - r = -ENOMEM; - goto put_fd; - } kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm); fd_install(fd, file);