From patchwork Fri Jul 21 23:00:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 124148 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:9010:0:b0:3e4:2afc:c1 with SMTP id l16csp524195vqg; Fri, 21 Jul 2023 16:37:14 -0700 (PDT) X-Google-Smtp-Source: APBJJlHJuZ1kn+O8aTfdcp385OCytv+QZKD3WqdZ3tD+39jVxOMnLT8uyNKjowMNsfy04HdU7RJC X-Received: by 2002:a17:906:7686:b0:973:fd02:a41f with SMTP id o6-20020a170906768600b00973fd02a41fmr2944528ejm.40.1689982633814; Fri, 21 Jul 2023 16:37:13 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1689982633; cv=none; d=google.com; s=arc-20160816; b=HeN2RZgNiC0yWqzf/S9WQg8BZuVudFdz9hgdn6CuJq82JEXqUTXVg/6SqjBug7VNiZ eYoUEPAyJ0i9iunxQ38ATjQR+lWasTWEut0t1tw3fqK+rfCrI3pBNfEkIUt25FSr69wr zRSPE73QnapoZxnie6nCm6TebbsZiISLuW8HkUYzDlBK8XB3ROcaC2BPg6xPCtcL/Pt7 CVOCA7nttFq1Q3OAqehySa5nsgLasngx549JcjHwAeLAeU+fKhHKHOYBMM3IiB0W0ve8 aGAMlqlQI6dveQXinZcoE0BWimYR95xHgZFm/fhjMQFlyKahuIo3iTR9v+p/RP6pR5rj k8Ng== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:reply-to:dkim-signature; bh=usSK3yeb2+dbKuXeDCW9x7zKGJjv9CPmyUgQidtHNNE=; fh=sOnAx2GuCQaI5IJu7Mo1xgLCDrPH4l5HM1pSkvn/pIo=; b=KkgWs46h+JT8+PKugAspnuV6JmlwVVB827DirzZO+WhhQwp7wR53vLLYLeREhiWSZ/ GK7mJ3FVe2Yc6V+34+Rx23ooOkwfqemW75Hs0SJNMDTqQ8Z2UhIUt5Rkw+AIHPQM8MOJ jQMA1KqWSkg2iG/7LPXVf/JdhZCgXKWCP610rBrbFN7mGsdJruL6hwHnRp1e7B+PVBp4 OY8jrEuf+BWUdsGYR+MUY+oWk6hTxp94H3QnLh9HffPaIDUxPeekjKyqHEb9iFWsOLUx +X5+c2y5v/bRmh6lzubs/lLPwIFSuJOxn1kQZqYorug9d98VRsul0zc2H+5XywbhA3bM tT1Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b="y1ewr/kb"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id p26-20020a170906141a00b00993664a9970si2887083ejc.873.2023.07.21.16.36.45; Fri, 21 Jul 2023 16:37:13 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b="y1ewr/kb"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231312AbjGUXAy (ORCPT + 99 others); Fri, 21 Jul 2023 19:00:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231316AbjGUXAl (ORCPT ); Fri, 21 Jul 2023 19:00:41 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 848323C3D for ; Fri, 21 Jul 2023 16:00:28 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-569e7aec37bso28215937b3.2 for ; Fri, 21 Jul 2023 16:00:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689980427; x=1690585227; 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=usSK3yeb2+dbKuXeDCW9x7zKGJjv9CPmyUgQidtHNNE=; b=y1ewr/kbrOutA8ZR9xcOf7OlMOdxw6k07Xh+KfWIE5JsL+KhmTlZRyCEhNpAHfv87x ie7QOITXavYjalaAjDKeXxQMwYjdQPvh7z+EaFByJvIgPz+DmyjSWp6GSdvQriAwM0Lf p+nf/mRt4XJCGhhorw6p3qGCi5tF/q/MSoiOaW4ofuVk7Hjpw4Z5Myh8bQ87UgCzU6Yc aQLyGCcnbkLKU0sBEkRgdd/xkiOJjKj/Qj/zWLX8yde8ERQtkxMVF/GAz4EnSPdHF0jQ yDpY/QJ4hCBXtx6pyOpZ/f6fjGbs1EKXZQ6ROP6h5PsdVYKo5B7DY+Vzfh+v998P/MiR 0kTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689980427; x=1690585227; 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=usSK3yeb2+dbKuXeDCW9x7zKGJjv9CPmyUgQidtHNNE=; b=GzpnhZ6kuKg36R0XU4IV9tDg4K5iPqGZCKKKAG/+TJb+Nx97yhESLg0313tvkiAY4y 3QOmT6QDD0n8j46qP8rA4PMXH/NmAw65FbgGqVwrUWu6lMc0bvXfK6w2w3NnQbGeDAtl HNueWwFfeYUBjlDgmSeIU/9UQQXRi6mC2OXfzcSRCxHO7EvEemigYLEaEORBAXwPTZNa Jg8ReTeCnXOXQ4T/5G2hZGOkebh7ueqcG4H+eHA27lhdEOlB1WnqpZKdLV74EWkrNvpX mO4nMUWncZJa3lYCrb15aiGLLNoeQRdCEKI1Yj85tWO/swk5WND0C5CWEO9TQFYH5T+l C+8g== X-Gm-Message-State: ABy/qLa96rzJ7u/duXe/HjBkGGhPW7Ce+GT/WRS+M8A0RGXx3YwfyrTp 0rGkKM6DXwTKr0jELV85w30nzsPu8U4= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a5b:bc2:0:b0:ce9:64b3:80dc with SMTP id c2-20020a5b0bc2000000b00ce964b380dcmr21029ybr.1.1689980427316; Fri, 21 Jul 2023 16:00:27 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 21 Jul 2023 16:00:06 -0700 In-Reply-To: <20230721230006.2337941-1-seanjc@google.com> Mime-Version: 1.0 References: <20230721230006.2337941-1-seanjc@google.com> X-Mailer: git-send-email 2.41.0.487.g6d72f3e995-goog Message-ID: <20230721230006.2337941-10-seanjc@google.com> Subject: [PATCH v2 9/9] KVM: x86/mmu: BUG() in rmap helpers iff CONFIG_BUG_ON_DATA_CORRUPTION=y From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Mingwei Zhang , David Matlack , Jim Mattson X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1772075230005640234 X-GMAIL-MSGID: 1772075230005640234 Introduce KVM_BUG_ON_DATA_CORRUPTION() and use it in the low-level rmap helpers to convert the existing BUG()s to WARN_ON_ONCE() when the kernel is built with CONFIG_BUG_ON_DATA_CORRUPTION=n, i.e. does NOT want to BUG() on corruption of host kernel data structures. Environments that don't have infrastructure to automatically capture crash dumps, i.e. aren't likely to enable CONFIG_BUG_ON_DATA_CORRUPTION=y, are typically better served overall by WARN-and-continue behavior (for the kernel, the VM is dead regardless), as a BUG() while holding mmu_lock all but guarantees the _best_ case scenario is a panic(). Make the BUG()s conditional instead of removing/replacing them entirely as there's a non-zero chance (though by no means a guarantee) that the damage isn't contained to the target VM, e.g. if no rmap is found for a SPTE then KVM may be double-zapping the SPTE, i.e. has already freed the memory the SPTE pointed at and thus KVM is reading/writing memory that KVM no longer owns. Link: https://lore.kernel.org/all/20221129191237.31447-1-mizhang@google.com Suggested-by: Mingwei Zhang Cc: David Matlack Cc: Jim Mattson Reviewed-by: Mingwei Zhang Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 21 ++++++++++----------- include/linux/kvm_host.h | 19 +++++++++++++++++++ 2 files changed, 29 insertions(+), 11 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index b6cc261d7748..69f65f7b6158 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -977,7 +977,7 @@ static void pte_list_desc_remove_entry(struct kvm *kvm, * when adding an entry and the previous head is full, and heads are * removed (this flow) when they become empty. */ - BUG_ON(j < 0); + KVM_BUG_ON_DATA_CORRUPTION(j < 0, kvm); /* * Replace the to-be-freed SPTE with the last valid entry from the head @@ -1008,14 +1008,13 @@ static void pte_list_remove(struct kvm *kvm, u64 *spte, struct pte_list_desc *desc; int i; - if (!rmap_head->val) { - pr_err("%s: %p 0->BUG\n", __func__, spte); - BUG(); - } else if (!(rmap_head->val & 1)) { - if ((u64 *)rmap_head->val != spte) { - pr_err("%s: %p 1->BUG\n", __func__, spte); - BUG(); - } + if (KVM_BUG_ON_DATA_CORRUPTION(!rmap_head->val, kvm)) + return; + + if (!(rmap_head->val & 1)) { + if (KVM_BUG_ON_DATA_CORRUPTION((u64 *)rmap_head->val != spte, kvm)) + return; + rmap_head->val = 0; } else { desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); @@ -1029,8 +1028,8 @@ static void pte_list_remove(struct kvm *kvm, u64 *spte, } desc = desc->more; } - pr_err("%s: %p many->many\n", __func__, spte); - BUG(); + + KVM_BUG_ON_DATA_CORRUPTION(true, kvm); } } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9d3ac7720da9..cb86108c624d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -865,6 +865,25 @@ static inline void kvm_vm_bugged(struct kvm *kvm) unlikely(__ret); \ }) +/* + * Note, "data corruption" refers to corruption of host kernel data structures, + * not guest data. Guest data corruption, suspected or confirmed, that is tied + * and contained to a single VM should *never* BUG() and potentially panic the + * host, i.e. use this variant of KVM_BUG() if and only if a KVM data structure + * is corrupted and that corruption can have a cascading effect to other parts + * of the hosts and/or to other VMs. + */ +#define KVM_BUG_ON_DATA_CORRUPTION(cond, kvm) \ +({ \ + bool __ret = !!(cond); \ + \ + if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) \ + BUG_ON(__ret); \ + else if (WARN_ON_ONCE(__ret && !(kvm)->vm_bugged)) \ + kvm_vm_bugged(kvm); \ + unlikely(__ret); \ +}) + static inline void kvm_vcpu_srcu_read_lock(struct kvm_vcpu *vcpu) { #ifdef CONFIG_PROVE_RCU