From patchwork Fri Oct 27 18:21:44 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 13438899 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 DDDEAC27C46 for ; Fri, 27 Oct 2023 18:22:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232550AbjJ0SWd (ORCPT ); Fri, 27 Oct 2023 14:22:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232662AbjJ0SWc (ORCPT ); Fri, 27 Oct 2023 14:22:32 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 686A112A for ; Fri, 27 Oct 2023 11:22:30 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-d815354ea7fso1672908276.1 for ; Fri, 27 Oct 2023 11:22:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698430949; x=1699035749; 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=Fn/2IBJw8IgyOIqoe5CTcghLJbfyq3WPHSyzyGJhcug=; b=39QyUmeajrHDHhG5YVcaFoKB+A6LJNfkc21vAg/MSsqP1QRmZ4ijZCI3+Vo7jOGgp9 c+yWikBszSU2V9+J6D5IEUzSWWvzt1NSYt6COPi+of+l0Fbk7rzi8Jcl00J/ocBHUYsU 1+qbBpPzIorOGL3r7deSFn3ubuNE+7knU7A5H4qkU1Mr56LYh8EWa7rWyXEhXtv6F8rU RgbgtDiz78QZlV4/ux6bhITo+aQD6UJOtSw+liTBPRh/2uHLsFTyJoqMbmqJKmu9ZU+7 6limj3Pq+1960Knnkm457oH7PtDMaOSzW2TywYUaUujlwQkMQ93T7qZ65YQawMxWnnns ijIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698430949; x=1699035749; 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=Fn/2IBJw8IgyOIqoe5CTcghLJbfyq3WPHSyzyGJhcug=; b=PWIu/jkJvn7vf/sovt0miyaM4XGk0TESFr8UYPZc1hHUKSp45rwpJZcPaihepAubjz nXzP3HsZLcRuwQbUJV0OWc1zxRt4S2T9qRExda+hwd9KaawtWS+8a1/cX3REdT3PPuG2 VJXa0r3jr12id9OjN3Ye2grLRLd9pxM7nSyeRYo5adz/GU1rt3XGLk0kRQ/cEU2Hddv2 yHjK2as/LTUCsDsDkhUNuMQsZUH7lqnXDREMlDZpHeVVYw0thBl/JADablGDE5nAXq41 AMDHpGrU2sJzdfka7Kl3zQDyTKeR4nDiZJlftbHJjpO/lenkJRiAa6Llvy5jMH1d+0kb LWXw== X-Gm-Message-State: AOJu0YzcnNZ1TYTKhIU2Rd6g/aGr6RGAc2ZoWTnGb3ibeA+ewEuIhqsE NZAkUkL7JqBeXS+UnFcOeyUJDzPGEek= X-Google-Smtp-Source: AGHT+IE/2A67BLmFvNwLQGxAeqfnMv4JVTEXFJ3uXVKssW9yJHFYWQUNgIG+FyGEOnQbWZWT52otjVeFu0A= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:1788:b0:da0:c9a5:b529 with SMTP id ca8-20020a056902178800b00da0c9a5b529mr57775ybb.12.1698430949628; Fri, 27 Oct 2023 11:22:29 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 27 Oct 2023 11:21:44 -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: <20231027182217.3615211-3-seanjc@google.com> Subject: [PATCH v13 02/35] KVM: Assert that mmu_invalidate_in_progress *never* goes negative 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_Sala?= =?utf-8?q?=C3=BCn?= " , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Move the assertion on the in-progress invalidation count from the primary MMU's notifier path to KVM's common notification path, i.e. assert that the count doesn't go negative even when the invalidation is coming from KVM itself. Opportunistically convert the assertion to a KVM_BUG_ON(), i.e. kill only the affected VM, not the entire kernel. A corrupted count is fatal to the VM, e.g. the non-zero (negative) count will cause mmu_invalidate_retry() to block any and all attempts to install new mappings. But it's far from guaranteed that an end() without a start() is fatal or even problematic to anything other than the target VM, e.g. the underlying bug could simply be a duplicate call to end(). And it's much more likely that a missed invalidation, i.e. a potential use-after-free, would manifest as no notification whatsoever, not an end() without a start(). Signed-off-by: Sean Christopherson Reviewed-by: Paolo Bonzini Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba --- virt/kvm/kvm_main.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 0524933856d4..5a97e6c7d9c2 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -833,6 +833,7 @@ void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start, * in conjunction with the smp_rmb in mmu_invalidate_retry(). */ kvm->mmu_invalidate_in_progress--; + KVM_BUG_ON(kvm->mmu_invalidate_in_progress < 0, kvm); } static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn, @@ -863,8 +864,6 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn, */ if (wake) rcuwait_wake_up(&kvm->mn_memslots_update_rcuwait); - - BUG_ON(kvm->mmu_invalidate_in_progress < 0); } static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,