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 CCA70C27C47 for ; Fri, 27 Oct 2023 18:22:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346376AbjJ0SWz (ORCPT ); Fri, 27 Oct 2023 14:22:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232301AbjJ0SWt (ORCPT ); Fri, 27 Oct 2023 14:22:49 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BC701A7 for ; Fri, 27 Oct 2023 11:22:34 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5af9ad9341fso10343357b3.2 for ; Fri, 27 Oct 2023 11:22:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698430953; x=1699035753; darn=vger.kernel.org; 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=QjG+iTAl+MysAoCDX0shLrWGCG7e9aCGlo9+qs2tVnE=; b=GboxU9hFYFXO5qn1IjUEXGWAanotm5uv6d1ExTIDSU+CqAkB5bQGwMOPxnCJiJ2RcF rskBiwmzeF4LFtGn05KtzZc75mc7Fgb1tJROrIoWu5x8TpL0w3dPacXbh1tFP2rkx4wi aKr41d8xZlA/twTU1EYsPqhC92vHOhoVPRVkM2QUSKue3+CrrAY+LR1b8XsZ7NhNdzkP RuAIuodjVsYyG9G7SKhfxPO9w9gLQaacaqP/LkACm2yD8+oEK0Mnymy6Sytll2Bz4HnH kxkLvjPS6LQTMuXn5GOk95y+c5bBGTJXGiDyVCQoyuvspd3vv8mBveA59LuCK6aL+udl bA9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698430953; x=1699035753; 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=QjG+iTAl+MysAoCDX0shLrWGCG7e9aCGlo9+qs2tVnE=; b=vVRopL29Us9NQ3MJPlFjG4Wb2R3OdY5CLzvlV3dXDiewtzK06ysfgAm8/0teTAEcZt wYPjaKVg1+kpxeyViKcbXgjYwTrw6IQ2inE7NlxVE4zjxLcmDv9LrP1WS2kQ2dv1HmLY s3RAJ6T1vUbN9bw9oM2khIrJ8KXyedK3sH0kwZBKhFTomSb/Tw9J+ANkLPZ8xF06zpno MCfZ98w8Cka0ngt0ycoF3ri5DYn4ZlZL00Lli0DTLuGZeOOmB992PTQnvaxtT07wrVYG +LJLK3rZWaeu2SMUIo75m9AmO3/fyU6cLslS+Itpg+IzMIHO6vRoZkUJpncPxeWcCRqJ 8zCQ== X-Gm-Message-State: AOJu0YyGeVNv9P3ZxZ4DIS2GNMgXQ9Na+ECx8eIsO3K7Zatt0BTOkHyl HACLL4IaQD2TT6S8POM0phJljRZiSKo= X-Google-Smtp-Source: AGHT+IFjdgmBdyxBQ0zr6Phdzdc3NhfRHFKE/+Wea1IZiVOT7T4IBQHOPkTpo2hU6PU86u42a7hH74NJYwo= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:1083:b0:da0:567d:f819 with SMTP id v3-20020a056902108300b00da0567df819mr78680ybu.10.1698430953673; Fri, 27 Oct 2023 11:22:33 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 27 Oct 2023 11:21:46 -0700 In-Reply-To: <20231027182217.3615211-1-seanjc@google.com> Mime-Version: 1.0 References: <20231027182217.3615211-1-seanjc@google.com> X-Mailer: git-send-email 2.42.0.820.g83a721a137-goog Message-ID: <20231027182217.3615211-5-seanjc@google.com> Subject: [PATCH v13 04/35] KVM: WARN if there are dangling MMU invalidations at VM destruction From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , "=?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?=" , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Add an assertion that there are no in-progress MMU invalidations when a VM is being destroyed, with the exception of the scenario where KVM unregisters its MMU notifier between an .invalidate_range_start() call and the corresponding .invalidate_range_end(). KVM can't detect unpaired calls from the mmu_notifier due to the above exception waiver, but the assertion can detect KVM bugs, e.g. such as the bug that *almost* escaped initial guest_memfd development. Link: https://lore.kernel.org/all/e397d30c-c6af-e68f-d18e-b4e3739c5389@linux.intel.com Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1a577a25de47..4dba682586ee 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1356,9 +1356,16 @@ static void kvm_destroy_vm(struct kvm *kvm) * No threads can be waiting in kvm_swap_active_memslots() as the * last reference on KVM has been dropped, but freeing * memslots would deadlock without this manual intervention. + * + * If the count isn't unbalanced, i.e. KVM did NOT unregister its MMU + * notifier between a start() and end(), then there shouldn't be any + * in-progress invalidations. */ WARN_ON(rcuwait_active(&kvm->mn_memslots_update_rcuwait)); - kvm->mn_active_invalidate_count = 0; + if (kvm->mn_active_invalidate_count) + kvm->mn_active_invalidate_count = 0; + else + WARN_ON(kvm->mmu_invalidate_in_progress); #else kvm_flush_shadow_all(kvm); #endif -- 2.42.0.820.g83a721a137-goog