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 37362C433FE for ; Fri, 15 Apr 2022 00:43:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348130AbiDOAqT (ORCPT ); Thu, 14 Apr 2022 20:46:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348099AbiDOAqP (ORCPT ); Thu, 14 Apr 2022 20:46:15 -0400 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E414C1D0CA for ; Thu, 14 Apr 2022 17:43:48 -0700 (PDT) Received: by mail-pg1-x54a.google.com with SMTP id w3-20020a639343000000b003821fb4a367so3459207pgm.21 for ; Thu, 14 Apr 2022 17:43:48 -0700 (PDT) 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=WHJorEYqdPsyoiS8LBeb1G8S4S7kzQkyLWZGD9aUrjs=; b=bZwTwRaSjFo3UIyEnG1Se3GCFh+RY6IvOG3VlupdDpfNfI6GX6hkJeLI81eGmOGX6G 1cHm7fTg8TqH04RjFv10Of5DvAYAHAM8tiEPrQRiuCNBDJRSzCUDQUG0BMRWHtD+LdNa OXpZzAre9wRSs/2YHv0GHmqXz+Pqefc9fuZxtMcl8GYafBb9wbzvPCjbT/nzQhtpz2Wn fyyyAL63cPcu44vOIB0qfBetcyUX/9l8dZ2b05Q4AfOcPl4SLNf/Fbj41CZv9b/yvg1F Aer1piomJTMTT3b0SNhbaUMWvPS5/iUeOlL+Pvad6lLyGugPdHlz8JZmH21Rl+8vgLjA mBcA== 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=WHJorEYqdPsyoiS8LBeb1G8S4S7kzQkyLWZGD9aUrjs=; b=irc5sfjs+uzjEYgTApHbxYmXUBzBSP0sGiksKdX8nm0Rf3NeRdFV8kIqIjmpWF/C2W /lVkcAm+fV0ptnKvonP648timQeQTBkvOLL5EDnD7jd63bR5hLurvxfdSvPU1pqstAS5 NbVtFEjcWuHbtyK2kbjEnELcEaut5Bn+yVVfWxJXvKUmzB7DaqZG6HGdqnnQPbewI3rf lP0lcvtk3Pw2zOl/ET/L2h/A6Amzh+ck0VYyfcxZTRZwrWuVUPJmhxGtj+/k+yhNNb+i alDplSqK16QR+nwyz1kF1xhvWi7C805yHWI7GkaExfb2YohmKQOJVHwkA8e5emZdA/at JyVw== X-Gm-Message-State: AOAM531+vzzij85AsdAMT/ZkN9YH8rINLxCDY+ye71wSQhRZfQBl74IO 1piUMSYZgFCImF0QXMyeC5YOtqEXQLg= X-Google-Smtp-Source: ABdhPJzt0tscL0kcshOCrjwd8G3ruQcGXCkqq7xMYex2fkXBeIa/R8tC7xq7T2RAxBd1S9ySsMfZwzJ54UU= X-Received: from seanjc.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e5]) (user=seanjc job=sendgmr) by 2002:a17:90b:4b84:b0:1cb:6cf5:d2ff with SMTP id lr4-20020a17090b4b8400b001cb6cf5d2ffmr1311935pjb.41.1649983428416; Thu, 14 Apr 2022 17:43:48 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 15 Apr 2022 00:43:41 +0000 In-Reply-To: <20220415004343.2203171-1-seanjc@google.com> Message-Id: <20220415004343.2203171-2-seanjc@google.com> Mime-Version: 1.0 References: <20220415004343.2203171-1-seanjc@google.com> X-Mailer: git-send-email 2.36.0.rc0.470.gd361397f0d-goog Subject: [PATCH 1/3] KVM: x86: Don't re-acquire SRCU lock in complete_emulated_io() From: Sean Christopherson To: Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Paolo Bonzini Cc: Atish Patra , David Hildenbrand , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Don't re-acquire SRCU in complete_emulated_io() now that KVM acquires the lock in kvm_arch_vcpu_ioctl_run(). More importantly, don't overwrite vcpu->srcu_idx. If the index acquired by complete_emulated_io() differs from the one acquired by kvm_arch_vcpu_ioctl_run(), KVM will effectively leak a lock and hang if/when synchronize_srcu() is invoked for the relevant grace period. Fixes: 8d25b7beca7e ("KVM: x86: pull kvm->srcu read-side to kvm_arch_vcpu_ioctl_run") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ab336f7c82e4..f35fe09de59d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10450,12 +10450,7 @@ static int vcpu_run(struct kvm_vcpu *vcpu) static inline int complete_emulated_io(struct kvm_vcpu *vcpu) { - int r; - - vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); - r = kvm_emulate_instruction(vcpu, EMULTYPE_NO_DECODE); - srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); - return r; + return kvm_emulate_instruction(vcpu, EMULTYPE_NO_DECODE); } static int complete_emulated_pio(struct kvm_vcpu *vcpu) -- 2.36.0.rc0.470.gd361397f0d-goog