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 82882C433F5 for ; Wed, 2 Feb 2022 00:50:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243624AbiBBAuP (ORCPT ); Tue, 1 Feb 2022 19:50:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243598AbiBBAuH (ORCPT ); Tue, 1 Feb 2022 19:50:07 -0500 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 77932C06173D for ; Tue, 1 Feb 2022 16:50:07 -0800 (PST) Received: by mail-pg1-x549.google.com with SMTP id t1-20020a6564c1000000b002e7f31cf59fso11297243pgv.14 for ; Tue, 01 Feb 2022 16:50:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=3/7OuVceBn0EleUU7nySvspzg5VyH7dxhNHRLM/3NIE=; b=EtaUGeB0crakORjKPe7ruh7EgNS85rRKIo1vZQSAgHFcEudyPUz4RuiIq+KtjJYiZR 1OqL25OxkYDNrCXKWKLz2YOtA4ckbOSJ3+YP4TfziGxQnMIEELSoi06HE/9CeAUSLKXU kSy5TvR9DjgowQ6RUPus4vXm0kcKZIN0W/4GBqjk0cAptuQUniCap/nPA6FskhIFtUeQ TTChArhpBpKfLOJe2aEt4MAxjHdkfSWQ++Di3jyS/VRH2ieCQD9GR20lU+klsKYnE5iY Fk4wRG/2OAgDLpvQ3U/NmazfqzqkzoGGPPqm8cy9lzbAKtPwG/yzEg1DGV4eFnlG7ZaS qHGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=3/7OuVceBn0EleUU7nySvspzg5VyH7dxhNHRLM/3NIE=; b=FYg29m1IbEuqyY7zdTiOtx5c4LHEMzo2S3VQ0d4H/DZyo2n+S9SgNjNivtWVqn9FO5 zVmt4QstQQMWxRoKviVkmpY2oFWKmNhHc8WKMtGIhNbGbntPrRTsVPlhbvTUNITtKp2t gcfCd/L2fJZHeVeuHW5sWxYN27Lsgl28+mx/28AzOMZ8+nHW1fHVzIK5sgTmBky5kPDX 4XQwhdRS06BPnnKSw94Z273mRX8XXBm0zollXv8k0RlbSWERunx53BdudtIx7GIDlgZC g77uj3QNHZ77Q7S9fVCAhBQ10vaM3cEoPGPXo1vhPr4Z+PYoOk+STWL7toU5aK6h7bNU OOag== X-Gm-Message-State: AOAM530eSPhCtRj8lqvH9gFQzuPEgaZLK8NwBScqsZyh6gcm16D/BpTs x8BpaVrComKaPYo/XDZB6kqouXW4QYg= X-Google-Smtp-Source: ABdhPJxaOUM0XxNVSnap4U+XQvTqFWJQ1EEDHMwv7ezGfJzzItoGIpIVtAqpcjtk78QdP1E/SRU2o8215xU= X-Received: from seanjc.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e5]) (user=seanjc job=sendgmr) by 2002:a17:902:b212:: with SMTP id t18mr13193260plr.80.1643763007012; Tue, 01 Feb 2022 16:50:07 -0800 (PST) Reply-To: Sean Christopherson Date: Wed, 2 Feb 2022 00:49:45 +0000 In-Reply-To: <20220202004945.2540433-1-seanjc@google.com> Message-Id: <20220202004945.2540433-6-seanjc@google.com> Mime-Version: 1.0 References: <20220202004945.2540433-1-seanjc@google.com> X-Mailer: git-send-email 2.35.0.rc2.247.g8bbb082509-goog Subject: [PATCH v2 5/5] KVM: x86: Bail to userspace if emulation of atomic user access faults From: Sean Christopherson To: Paolo Bonzini , Nathan Chancellor , Nick Desaulniers Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, llvm@lists.linux.dev, linux-kernel@vger.kernel.org, Peter Zijlstra , Tadeusz Struk , syzbot+6cde2282daa792c49ab8@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Exit to userspace when emulating an atomic guest access if the CMPXCHG on the userspace address faults. Emulating the access as a write and thus likely treating it as emulated MMIO is wrong, as KVM has already confirmed there is a valid, writable memslot. Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c9cac3100f77..24e0981816c0 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7217,7 +7217,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, } if (r < 0) - goto emul_write; + return X86EMUL_UNHANDLEABLE; if (r) return X86EMUL_CMPXCHG_FAILED; -- 2.35.0.rc2.247.g8bbb082509-goog