From mboxrd@z Thu Jan 1 00:00:00 1970 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 0DEEBC4321E for ; Wed, 30 Nov 2022 23:09:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229604AbiK3XJq (ORCPT ); Wed, 30 Nov 2022 18:09:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229686AbiK3XJk (ORCPT ); Wed, 30 Nov 2022 18:09:40 -0500 Received: from mail-oi1-x24a.google.com (mail-oi1-x24a.google.com [IPv6:2607:f8b0:4864:20::24a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3AFC57B51 for ; Wed, 30 Nov 2022 15:09:39 -0800 (PST) Received: by mail-oi1-x24a.google.com with SMTP id c11-20020a056808138b00b0035a17dd854dso146845oiw.0 for ; Wed, 30 Nov 2022 15:09:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=S5armvpc10OdJc+V4p2ZjsfPOSB2+gt+Iv6GXjLvIxarCpnvSzXAszP1ZRQLfxrpVn 4VKntdMIRcH9d5x9XG1oGb5HbZFayk+JATeZBYQSlvM+DpwmfecZQ8AsDtvEHJv8Um6T UA3gJNgXD7v57R6+HWMBuEe+F5z07hORTUOLfSKyijFbwT8eHearvUCVMdt7/m5zjOT/ RJHYTQwmhGaPhaOc8DfHyXLVsjojQiPBCzNQuFpX8g3cosCwY+5F+o1XrOjsJNDhsv4X dI+LD+RMI6RHxUg1kkU/xRepaC5EvnuL3x5vvCzRlD3QPj+jjInfZWGepttgPw2FHtVt S1mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=Zca+4tIyltacz7Yz8TM1UNQdUZJe8YgJc6ZakxwrD9ffT0MJZqz0ppdpJKW6o88NbL 0P8RlgyXPC4pcmHV2QKSnZ/sZbXZ0olPIIswFYp+8EJezeQn/YFn55Yh8B7qj/3hFTzT RG11GymHmcn9aShShW/dM0vLTW4AU2oU60iuBej0F6TV6E9wM5hfKwQN9OAyGXZQ3Tn0 CdJ6KgHedrecMc3hWDhwb5ghmqRevp5KeYhPGFKK1ARUq7wv5BSyhakWq4Le4vyDBjDX W2Qzib0QOyCT8tk6uC8ODTb7BsuPdjMZpX8p3Egxju4o61DdkHgz4QQpLVic/zvoi25c wAGA== X-Gm-Message-State: ANoB5pn9ot0olYM33sU3tEBL1gzyC8JBoNNLStHbMtDCwHG0B4Bvr2YK B8bcR1cYAiLdsAn4PBMgP8ECOje7FuY= X-Google-Smtp-Source: AA0mqf5M2pMTumXNgDe8Hfk4OhWDWk4TI1AuNKSU3xW+oTTlboWhE7bh5wRjvWcn8RwiB3BV7R0iM4jxw2w= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6870:bb1a:b0:143:74c2:f928 with SMTP id nw26-20020a056870bb1a00b0014374c2f928mr15086226oab.64.1669849778974; Wed, 30 Nov 2022 15:09:38 -0800 (PST) Reply-To: Sean Christopherson Date: Wed, 30 Nov 2022 23:08:45 +0000 In-Reply-To: <20221130230934.1014142-1-seanjc@google.com> Mime-Version: 1.0 References: <20221130230934.1014142-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog Message-ID: <20221130230934.1014142-2-seanjc@google.com> Subject: [PATCH v2 01/50] KVM: Register /dev/kvm as the _very_ last thing during initialization From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Sean Christopherson , Vitaly Kuznetsov , David Woodhouse , Paul Durrant Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Yuan Yao , Cornelia Huck , Isaku Yamahata , "=?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?=" , Fabiano Rosas , Michael Ellerman , Kai Huang , Chao Gao , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1782c4555d94..b60abb03606b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5919,12 +5919,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -5933,11 +5927,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -5963,8 +5970,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache); -- 2.38.1.584.g0f3c55d4c2-goog From mboxrd@z Thu Jan 1 00:00:00 1970 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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3263DC4321E for ; Wed, 30 Nov 2022 23:09:46 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 5F3A4403A6; Wed, 30 Nov 2022 18:09:45 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id apYQlsXgd5AE; Wed, 30 Nov 2022 18:09:43 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 054AD4B125; Wed, 30 Nov 2022 18:09:42 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9F45C4086D for ; Wed, 30 Nov 2022 18:09:41 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id UcteivbVuJ+T for ; Wed, 30 Nov 2022 18:09:39 -0500 (EST) Received: from mail-oa1-f74.google.com (mail-oa1-f74.google.com [209.85.160.74]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id D4FA840B8F for ; Wed, 30 Nov 2022 18:09:39 -0500 (EST) Received: by mail-oa1-f74.google.com with SMTP id 586e51a60fabf-13b9bcc6b4cso105160fac.13 for ; Wed, 30 Nov 2022 15:09:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=S5armvpc10OdJc+V4p2ZjsfPOSB2+gt+Iv6GXjLvIxarCpnvSzXAszP1ZRQLfxrpVn 4VKntdMIRcH9d5x9XG1oGb5HbZFayk+JATeZBYQSlvM+DpwmfecZQ8AsDtvEHJv8Um6T UA3gJNgXD7v57R6+HWMBuEe+F5z07hORTUOLfSKyijFbwT8eHearvUCVMdt7/m5zjOT/ RJHYTQwmhGaPhaOc8DfHyXLVsjojQiPBCzNQuFpX8g3cosCwY+5F+o1XrOjsJNDhsv4X dI+LD+RMI6RHxUg1kkU/xRepaC5EvnuL3x5vvCzRlD3QPj+jjInfZWGepttgPw2FHtVt S1mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=zBUFSRP6HbouYBWJiOFpdo9SZa4bWF/bqOaoyjluHsNw2uFNn6+7mYa4riaBTBNEPN yT8v71lzTHdI7IpFeMPAKzWocQxbYTtvrsbO4uIw1lFCy2V+qwS/rP9FsVHEk1o7fy9q leicovssOgl7PaNVdGEPXD+WSkojl39f+V29aqSYWmmqPJts0vKvgcgOAltG5oxSl0YQ Y4EwG7gmKGojJPLvnE+FckLu3OZgQisZ1f1O45qROFXBPz9PS4FwgmubPB8bty6Dg1vv BVpHLD1KIvs/6PY9Ay/BHZVPCYDTIazw+0/PYLi0BU01wtDSQGhblNyfV0Is2gsLDDNz C7ug== X-Gm-Message-State: ANoB5pnS7zZC+EDr6N9pC0KpPxv2wgmSu9BNL/OJvK7cM92BGlBU5Ry3 fQAXt35SajEzUyyOq8ygoeQIv8ghB4o= X-Google-Smtp-Source: AA0mqf5M2pMTumXNgDe8Hfk4OhWDWk4TI1AuNKSU3xW+oTTlboWhE7bh5wRjvWcn8RwiB3BV7R0iM4jxw2w= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6870:bb1a:b0:143:74c2:f928 with SMTP id nw26-20020a056870bb1a00b0014374c2f928mr15086226oab.64.1669849778974; Wed, 30 Nov 2022 15:09:38 -0800 (PST) Date: Wed, 30 Nov 2022 23:08:45 +0000 In-Reply-To: <20221130230934.1014142-1-seanjc@google.com> Mime-Version: 1.0 References: <20221130230934.1014142-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog Message-ID: <20221130230934.1014142-2-seanjc@google.com> Subject: [PATCH v2 01/50] KVM: Register /dev/kvm as the _very_ last thing during initialization From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Sean Christopherson , Vitaly Kuznetsov , David Woodhouse , Paul Durrant Cc: kvm@vger.kernel.org, David Hildenbrand , Atish Patra , linux-kernel@vger.kernel.org, Kai Huang , linux-riscv@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Michael Ellerman , Chao Gao , Yuan Yao , kvmarm@lists.linux.dev, Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Fabiano Rosas , Cornelia Huck , linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list Reply-To: Sean Christopherson List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1782c4555d94..b60abb03606b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5919,12 +5919,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -5933,11 +5927,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -5963,8 +5970,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache); -- 2.38.1.584.g0f3c55d4c2-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 38FAEC352A1 for ; Wed, 30 Nov 2022 23:10:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Reply-To:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID :References:Mime-Version:In-Reply-To:Date:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=mgi7pOqaf0EO1l3pLpFIfrqe2J91JUwpwNweqsrtOaE=; b=loS0F87mk9EvzE el9CXhW063GLPd2rEvU03CF9SlNOP7w7k38v4dGopW+un+mc9ywGlAzijTUIp9zCYZb55AU0nDgb2 wA0uAG2In9uS8EubcBSQDIazIwNQX+DeF4Q5Gf/9YR6jyQj0xfoza/pb9sfGPZF7zRAgp28wQX09Y nZX7VYG3udzfYAnpcEJ1n4tESgXztqBF6D0H6d8kmotsgPu8FOUiV/TtCDvu0/1nlCYEo8WHYM4As RLusyclk7Qai4ITZ0hbLS3h/wOfCjGoxDzEBxqVhPXCm0mo9UmESuARyRnD68nBxhgQxBrrajsskP fwNkch99RCtD57hi/j8A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1p0WDM-0036IB-Lp; Wed, 30 Nov 2022 23:10:04 +0000 Received: from mail-oa1-x4a.google.com ([2001:4860:4864:20::4a]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1p0WCz-00362V-Kk for linux-riscv@lists.infradead.org; Wed, 30 Nov 2022 23:09:43 +0000 Received: by mail-oa1-x4a.google.com with SMTP id 586e51a60fabf-14289aba38aso96083fac.18 for ; Wed, 30 Nov 2022 15:09:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=S5armvpc10OdJc+V4p2ZjsfPOSB2+gt+Iv6GXjLvIxarCpnvSzXAszP1ZRQLfxrpVn 4VKntdMIRcH9d5x9XG1oGb5HbZFayk+JATeZBYQSlvM+DpwmfecZQ8AsDtvEHJv8Um6T UA3gJNgXD7v57R6+HWMBuEe+F5z07hORTUOLfSKyijFbwT8eHearvUCVMdt7/m5zjOT/ RJHYTQwmhGaPhaOc8DfHyXLVsjojQiPBCzNQuFpX8g3cosCwY+5F+o1XrOjsJNDhsv4X dI+LD+RMI6RHxUg1kkU/xRepaC5EvnuL3x5vvCzRlD3QPj+jjInfZWGepttgPw2FHtVt S1mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=gANjoo011dKcKlQ6weQje7CDd2fB+l1oKS0e12YS+XP4f9s4lmDGAe3RWQ/+OXAiQb 6DxkpKp1kS1c35vfP42PLvR4ryx4+LjbcEO8iPvk9SQmQcDQaVZjTuiPMC+JElNtjT0a oehuxGoDqS3dJKcWfXIwfdfux3npznR0on2jvGU+wjiXINlf9B6DFDXBZb8Lu4VSHhvK CT3vvWzQpkuTf93o4SyXHGyDhrOVyDOkPw4IeVT1Q/yJC+lWSgZAYP+/a0Law126Q4ll Ep+K1V0fuZFb+tjvEg4AfQk2szh6ElnMbF0y3Np7cHbG2l1f30Da59zoYEz4e9B7MgP3 yI9A== X-Gm-Message-State: ANoB5pkB+jVbE0nBRKoxyG7ZakiagA75Qe94lduyXLetTsYp1J7EXfd1 EHl5siP+/p5/FDebgAbajKb+voibsxA= X-Google-Smtp-Source: AA0mqf5M2pMTumXNgDe8Hfk4OhWDWk4TI1AuNKSU3xW+oTTlboWhE7bh5wRjvWcn8RwiB3BV7R0iM4jxw2w= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6870:bb1a:b0:143:74c2:f928 with SMTP id nw26-20020a056870bb1a00b0014374c2f928mr15086226oab.64.1669849778974; Wed, 30 Nov 2022 15:09:38 -0800 (PST) Date: Wed, 30 Nov 2022 23:08:45 +0000 In-Reply-To: <20221130230934.1014142-1-seanjc@google.com> Mime-Version: 1.0 References: <20221130230934.1014142-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog Message-ID: <20221130230934.1014142-2-seanjc@google.com> Subject: [PATCH v2 01/50] KVM: Register /dev/kvm as the _very_ last thing during initialization From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Sean Christopherson , Vitaly Kuznetsov , David Woodhouse , Paul Durrant Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Yuan Yao , Cornelia Huck , Isaku Yamahata , "=?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?=" , Fabiano Rosas , Michael Ellerman , Kai Huang , Chao Gao , Thomas Gleixner X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221130_150941_707574_57A40708 X-CRM114-Status: GOOD ( 11.71 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1782c4555d94..b60abb03606b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5919,12 +5919,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -5933,11 +5927,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -5963,8 +5970,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache); -- 2.38.1.584.g0f3c55d4c2-goog _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv From mboxrd@z Thu Jan 1 00:00:00 1970 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8B5C7C4708D for ; Wed, 30 Nov 2022 23:10:35 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NMw0n6p2bz3bWP for ; Thu, 1 Dec 2022 10:10:33 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=S5armvpc; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=flex--seanjc.bounces.google.com (client-ip=2607:f8b0:4864:20::249; helo=mail-oi1-x249.google.com; envelope-from=3sukhywykdlkrdzmibfnnfkd.bnlkhmtwoob-cdukhrsr.nykzar.nqf@flex--seanjc.bounces.google.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=S5armvpc; dkim-atps=neutral Received: from mail-oi1-x249.google.com (mail-oi1-x249.google.com [IPv6:2607:f8b0:4864:20::249]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4NMvzq2grxz304s for ; Thu, 1 Dec 2022 10:09:41 +1100 (AEDT) Received: by mail-oi1-x249.google.com with SMTP id bf10-20020a056808190a00b0035a0a5ab8b6so114661oib.11 for ; Wed, 30 Nov 2022 15:09:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=S5armvpc10OdJc+V4p2ZjsfPOSB2+gt+Iv6GXjLvIxarCpnvSzXAszP1ZRQLfxrpVn 4VKntdMIRcH9d5x9XG1oGb5HbZFayk+JATeZBYQSlvM+DpwmfecZQ8AsDtvEHJv8Um6T UA3gJNgXD7v57R6+HWMBuEe+F5z07hORTUOLfSKyijFbwT8eHearvUCVMdt7/m5zjOT/ RJHYTQwmhGaPhaOc8DfHyXLVsjojQiPBCzNQuFpX8g3cosCwY+5F+o1XrOjsJNDhsv4X dI+LD+RMI6RHxUg1kkU/xRepaC5EvnuL3x5vvCzRlD3QPj+jjInfZWGepttgPw2FHtVt S1mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=YsfONxWIfeLgjMHkxrGjd06jxLkjwEzzFgsbuHEq6xdU16vmJpYbzfaPPQGl8t9HM1 BIFtgJX4/M98BEXywEsmqybNBqQnfEXTRmzHS0g4ckjczP709AXD4v67K6aW2WG1xaK5 zUN6yFIXAKmaMHlsjhtZHU1zKCf6jDnupkUmJcKki71UkyDcUAGjjh5huEUxeTFjUdaQ zki9Hz17B2kNn9daYY3jRdafNLZH858qe3qSo9/koHiegZqM3s2CD2EGW3ECa0ieLbmb xTEbopaLwFHTOZi62DnvP069NW35RuKldxfQXZQz4JtAHiB86HAVTNpOABak1FnXZsVz xA4Q== X-Gm-Message-State: ANoB5pm6CSCAcn4QhZRuKjwFw9melMfIwfCleFRlijaiky9b42f0gugt KHt+zl3nelvCrWcm4BoI/InZK4dBzSg= X-Google-Smtp-Source: AA0mqf5M2pMTumXNgDe8Hfk4OhWDWk4TI1AuNKSU3xW+oTTlboWhE7bh5wRjvWcn8RwiB3BV7R0iM4jxw2w= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6870:bb1a:b0:143:74c2:f928 with SMTP id nw26-20020a056870bb1a00b0014374c2f928mr15086226oab.64.1669849778974; Wed, 30 Nov 2022 15:09:38 -0800 (PST) Date: Wed, 30 Nov 2022 23:08:45 +0000 In-Reply-To: <20221130230934.1014142-1-seanjc@google.com> Mime-Version: 1.0 References: <20221130230934.1014142-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog Message-ID: <20221130230934.1014142-2-seanjc@google.com> Subject: [PATCH v2 01/50] KVM: Register /dev/kvm as the _very_ last thing during initialization From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Sean Christopherson , Vitaly Kuznetsov , David Woodhouse , Paul Durrant Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Cc: kvm@vger.kernel.org, David Hildenbrand , Atish Patra , linux-kernel@vger.kernel.org, Kai Huang , linux-riscv@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Chao Gao , Suzuki K Poulose , Yuan Yao , kvmarm@lists.linux.dev, Thomas Gleixner , Alexandru Elisei , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Fabiano Rosas , Cornelia Huck , linux-mips@vger.kernel.org, Oliver Upton , James Morse , kvm-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1782c4555d94..b60abb03606b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5919,12 +5919,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -5933,11 +5927,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -5963,8 +5970,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache); -- 2.38.1.584.g0f3c55d4c2-goog From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DF539C47088 for ; Wed, 30 Nov 2022 23:10:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Reply-To:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID :References:Mime-Version:In-Reply-To:Date:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=b3hCITShcudSNXA9W8AgkIW6H/XNdOIuVdy3yBJ64lQ=; b=dnrictwg+GJ9Xc cDRDg5OwCsTE+DC/kQPgA8KnNT08bNtNympYhekWqRRL+IwXE/4j4jTxMQCNSPISWXxd7b8UIoM7M s3v0TWf808MVbraqIcYyTX/G2TgjFO5a63QyVOqKMx2tYXI8W3hl2pBQrx2+zTQ/WknEhkEv9Z4Uo Uqkt4qwWPZrwAwlHsV87t11tbsmpGVgZa88qdbZD+V1Du8pgIaOnbb7ro+UhqI97vCtqMM6fW+4ZT Tjru2+WhF9cMhdm8zGCNuwMy94zp30OFDwfgJEGbLvWJpCG/bfdFmBM2A2SnRJUMbK+P6tLYghQ2g P51XflR3njVhvgbWNLkQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1p0WDD-0036D8-PQ; Wed, 30 Nov 2022 23:09:55 +0000 Received: from mail-oi1-x24a.google.com ([2607:f8b0:4864:20::24a]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1p0WCz-00362U-MI for linux-arm-kernel@lists.infradead.org; Wed, 30 Nov 2022 23:09:43 +0000 Received: by mail-oi1-x24a.google.com with SMTP id m8-20020a056808024800b0035b120cb412so127209oie.3 for ; Wed, 30 Nov 2022 15:09:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=S5armvpc10OdJc+V4p2ZjsfPOSB2+gt+Iv6GXjLvIxarCpnvSzXAszP1ZRQLfxrpVn 4VKntdMIRcH9d5x9XG1oGb5HbZFayk+JATeZBYQSlvM+DpwmfecZQ8AsDtvEHJv8Um6T UA3gJNgXD7v57R6+HWMBuEe+F5z07hORTUOLfSKyijFbwT8eHearvUCVMdt7/m5zjOT/ RJHYTQwmhGaPhaOc8DfHyXLVsjojQiPBCzNQuFpX8g3cosCwY+5F+o1XrOjsJNDhsv4X dI+LD+RMI6RHxUg1kkU/xRepaC5EvnuL3x5vvCzRlD3QPj+jjInfZWGepttgPw2FHtVt S1mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Ol+f04sMmomAVy3XzqNXK+ShxWrn6gIN96B7OKl5yaM=; b=kV2L45Gkafvt4BRdP4MIUvOgp63nOUCCyLT7z6Lc3ZrW2JmRjq+eduaCAumTwHaVhW ANj579ehWsrIsGyObRigXLr8fk/E50OAiU6B2LPE/4th3fsSrkajxsS96kwV+8+xEhlE Br/n4iW4XJP/CMCgxbrWpW5Ga4qpSsiy06I+YCcCN6Ir4Jsy4Yp1WWv0m9mNMaz03fMn P4wE7kptYhLROyfEBM5CyLDPQL8oTGGHziTzldDIs98fynvKv6GwYLy4Jj6CP3V1ZS/l GS05ldli8qp1HtIm0p+OMOzAQKec22YRdmUbkKGaU/x2UiKQ6OJ/m5RWYHU4dxvCs4IA lnGQ== X-Gm-Message-State: ANoB5pkD7+vVTZbYU+mlZbFIUurBVVr5lU+hS0VFduWswoX1xKURJq+7 IcfKKC1a4MJ7ouuX46NRdqmjdNSOZDI= X-Google-Smtp-Source: AA0mqf5M2pMTumXNgDe8Hfk4OhWDWk4TI1AuNKSU3xW+oTTlboWhE7bh5wRjvWcn8RwiB3BV7R0iM4jxw2w= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6870:bb1a:b0:143:74c2:f928 with SMTP id nw26-20020a056870bb1a00b0014374c2f928mr15086226oab.64.1669849778974; Wed, 30 Nov 2022 15:09:38 -0800 (PST) Date: Wed, 30 Nov 2022 23:08:45 +0000 In-Reply-To: <20221130230934.1014142-1-seanjc@google.com> Mime-Version: 1.0 References: <20221130230934.1014142-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog Message-ID: <20221130230934.1014142-2-seanjc@google.com> Subject: [PATCH v2 01/50] KVM: Register /dev/kvm as the _very_ last thing during initialization From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Sean Christopherson , Vitaly Kuznetsov , David Woodhouse , Paul Durrant Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Yuan Yao , Cornelia Huck , Isaku Yamahata , "=?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?=" , Fabiano Rosas , Michael Ellerman , Kai Huang , Chao Gao , Thomas Gleixner X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221130_150941_746017_01A4D833 X-CRM114-Status: GOOD ( 13.24 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Register /dev/kvm, i.e. expose KVM to userspace, only after all other setup has completed. Once /dev/kvm is exposed, userspace can start invoking KVM ioctls, creating VMs, etc... If userspace creates a VM before KVM is done with its configuration, bad things may happen, e.g. KVM will fail to properly migrate vCPU state if a VM is created before KVM has registered preemption notifiers. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1782c4555d94..b60abb03606b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5919,12 +5919,6 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_chardev_ops.owner = module; - r = misc_register(&kvm_dev); - if (r) { - pr_err("kvm: misc device register failed\n"); - goto out_unreg; - } - register_syscore_ops(&kvm_syscore_ops); kvm_preempt_ops.sched_in = kvm_sched_in; @@ -5933,11 +5927,24 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, kvm_init_debug(); r = kvm_vfio_ops_init(); - WARN_ON(r); + if (WARN_ON_ONCE(r)) + goto err_vfio; + + /* + * Registration _must_ be the very last thing done, as this exposes + * /dev/kvm to userspace, i.e. all infrastructure must be setup! + */ + r = misc_register(&kvm_dev); + if (r) { + pr_err("kvm: misc device register failed\n"); + goto err_register; + } return 0; -out_unreg: +err_register: + kvm_vfio_ops_exit(); +err_vfio: kvm_async_pf_deinit(); out_free_4: for_each_possible_cpu(cpu) @@ -5963,8 +5970,14 @@ void kvm_exit(void) { int cpu; - debugfs_remove_recursive(kvm_debugfs_dir); + /* + * Note, unregistering /dev/kvm doesn't strictly need to come first, + * fops_get(), a.k.a. try_module_get(), prevents acquiring references + * to KVM while the module is being stopped. + */ misc_deregister(&kvm_dev); + + debugfs_remove_recursive(kvm_debugfs_dir); for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache); -- 2.38.1.584.g0f3c55d4c2-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel