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 X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B431C433DB for ; Thu, 28 Jan 2021 10:16:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1FFA64DD6 for ; Thu, 28 Jan 2021 10:16:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232023AbhA1KQy (ORCPT ); Thu, 28 Jan 2021 05:16:54 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:42886 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231811AbhA1KQm (ORCPT ); Thu, 28 Jan 2021 05:16:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611828914; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=264k/ES24/5FzBGHM2fYr7IzBwxBwCNGsVT8SMTVVPM=; b=ApM+nrpf7PV7A+Grhv8G2ZVY2I9Gtx6KXf19qlq4Tsr7/J+WaCMQb7cWXIl6/lxF43HAXC l87TI4BIaQchiYCZ6jZmQ37edDDv6ftjX4vLNCq4Ryar+/x4Dcg9LExCgHSY9GNdni8LJk hi4L1KouO7/nCn1AhUJjdUVcjatkRiQ= Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-396-bAzsECiPPdOlizDuaeO9wA-1; Thu, 28 Jan 2021 05:15:12 -0500 X-MC-Unique: bAzsECiPPdOlizDuaeO9wA-1 Received: by mail-ej1-f70.google.com with SMTP id ar27so835936ejc.22 for ; Thu, 28 Jan 2021 02:15:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=264k/ES24/5FzBGHM2fYr7IzBwxBwCNGsVT8SMTVVPM=; b=PKVCKozquDETifwQvhht7V64CJUVYHvN8U1HCjtljSuxJqPWkZdBBkQaA1snLs5Bc0 HHk6fBE6YcNjvMz/iP9dPI0YtzRNfcK4B8jucZXGCvj/3PDiYkcGQ5+APxk9G+W9C2EW eQhopAkECvBeWIiIzABXs3+6683UUCozZ49quO8HOyPY/8HzJ3B+SNp6GK2AftknvLh8 cKXrblHzdP4KQ/l3BaXSTAAW46PgB7yrAY2OxNAvswItfKOcKr0azmHTNYxWGjPbWyC+ Q6Lam3jXlr1cePrfQ/pYYDxJ74qwTKAT7XJxXe0IoxAxoh0k3Knqob5bwcr0rsuJhXVY WwrA== X-Gm-Message-State: AOAM532qFfhg1I02NUv6/GLThhSkrHDuFzizzsSEYzKVyU9tGH1KVjbm 6xweNX8DAgR9fXlwJP4MlnKwLHfOOEey6ml4/wGT8iaIB4r7mBznSvH/5vSBuCK9B5xP117twx1 u5j8WIsi08WUIjrespILTygpYSqpm1LcxKDaypCgpXiB7E0Zszr/SvrJspoelSjsV368r9JkR1E 22 X-Received: by 2002:a05:6402:556:: with SMTP id i22mr12971205edx.56.1611828911400; Thu, 28 Jan 2021 02:15:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJy4SAH7IU0R5i26466TR/gOXJqVjt6mKq2oIXhXos1oK+4OFr5vXHw1ve0htUjPFzXJN36T8Q== X-Received: by 2002:a05:6402:556:: with SMTP id i22mr12971163edx.56.1611828911092; Thu, 28 Jan 2021 02:15:11 -0800 (PST) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id f22sm2080999eje.34.2021.01.28.02.15.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Jan 2021 02:15:10 -0800 (PST) Subject: Re: [PATCH V2] Fix unsynchronized access to sev members through svm_register_enc_region To: Peter Gonda , kvm@vger.kernel.org Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Joerg Roedel , Tom Lendacky , Brijesh Singh , Sean Christopherson , x86@kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210127161524.2832400-1-pgonda@google.com> From: Paolo Bonzini Message-ID: Date: Thu, 28 Jan 2021 11:15:08 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210127161524.2832400-1-pgonda@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/01/21 17:15, Peter Gonda wrote: > Grab kvm->lock before pinning memory when registering an encrypted > region; sev_pin_memory() relies on kvm->lock being held to ensure > correctness when checking and updating the number of pinned pages. > > Add a lockdep assertion to help prevent future regressions. > > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: Paolo Bonzini > Cc: Joerg Roedel > Cc: Tom Lendacky > Cc: Brijesh Singh > Cc: Sean Christopherson > Cc: x86@kernel.org > Cc: kvm@vger.kernel.org > Cc: stable@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Fixes: 1e80fdc09d12 ("KVM: SVM: Pin guest memory when SEV is active") > Signed-off-by: Peter Gonda > > V2 > - Fix up patch description > - Correct file paths svm.c -> sev.c > - Add unlock of kvm->lock on sev_pin_memory error > > V1 > - https://lore.kernel.org/kvm/20210126185431.1824530-1-pgonda@google.com/ > > --- > arch/x86/kvm/svm/sev.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index c8ffdbc81709..b80e9bf0a31b 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -342,6 +342,8 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr, > unsigned long first, last; > int ret; > > + lockdep_assert_held(&kvm->lock); > + > if (ulen == 0 || uaddr + ulen < uaddr) > return ERR_PTR(-EINVAL); > > @@ -1119,12 +1121,20 @@ int svm_register_enc_region(struct kvm *kvm, > if (!region) > return -ENOMEM; > > + mutex_lock(&kvm->lock); > region->pages = sev_pin_memory(kvm, range->addr, range->size, ®ion->npages, 1); > if (IS_ERR(region->pages)) { > ret = PTR_ERR(region->pages); > + mutex_unlock(&kvm->lock); > goto e_free; > } > > + region->uaddr = range->addr; > + region->size = range->size; > + > + list_add_tail(®ion->list, &sev->regions_list); > + mutex_unlock(&kvm->lock); > + > /* > * The guest may change the memory encryption attribute from C=0 -> C=1 > * or vice versa for this memory range. Lets make sure caches are > @@ -1133,13 +1143,6 @@ int svm_register_enc_region(struct kvm *kvm, > */ > sev_clflush_pages(region->pages, region->npages); > > - region->uaddr = range->addr; > - region->size = range->size; > - > - mutex_lock(&kvm->lock); > - list_add_tail(®ion->list, &sev->regions_list); > - mutex_unlock(&kvm->lock); > - > return ret; > > e_free: > Queued, thanks. Paolo