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=-9.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 ED66EC55179 for ; Thu, 22 Oct 2020 11:37:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C8C42225F for ; Thu, 22 Oct 2020 11:37:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="0vJSIpfH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2897362AbgJVLhi (ORCPT ); Thu, 22 Oct 2020 07:37:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2444409AbgJVLhi (ORCPT ); Thu, 22 Oct 2020 07:37:38 -0400 Received: from mail-lf1-x141.google.com (mail-lf1-x141.google.com [IPv6:2a00:1450:4864:20::141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D252BC0613CE for ; Thu, 22 Oct 2020 04:37:37 -0700 (PDT) Received: by mail-lf1-x141.google.com with SMTP id 184so1829454lfd.6 for ; Thu, 22 Oct 2020 04:37:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=kV3B9d4XnVSsmv3sKzzsVoproWEhDGgfHQIXbtHyc80=; b=0vJSIpfHLs5Q3hF3srtH+miWg1YG4sQZe68J2f1r5Tj19mY8+VnxDOcKJKS/hXBj3h bEl6lwmsj7gyfoev3md9cI5h2iSLBNI2MRSRUkseK5n3SiJzDkKq4Efk6mqL6alfcBHu 7IKMuzGUediaJOB8gVnlN1UcPjLsVk/E0n2pLGJl3TUqDGXJ/yQxKy2KVvh+TrFLAex1 cy5kPIduOWsSLKvnp5yU9uGeKGla9JPNFgXU8O0al97cMMG41BvYZXrSZurVRuut9cF7 jD0RJeopeBAG+CcZ8JG/xtGZPkEjRNiqGgtiOvExPLy90MMUYxy5zxM79t/9HZJdcLhu 3YQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=kV3B9d4XnVSsmv3sKzzsVoproWEhDGgfHQIXbtHyc80=; b=dh/EgeQDzjwI4ybEjm7c0Mmxw3DGUhhATfs+OXz6ig0GTjT7XV3ZsDJayJ0PICalrB V4xwhqqXpz1tJApQAYQqcJ9PpCYV7wdb/rxrCaK4rviGhoA0TTRoQON6JDlNtz66EBWC dHyiNlCDLE4wMJfp4xwD3UaABdYyP9zNi7QXxKBKr/djNW4cigQsFFyYUM1hRNQAu5nH XUSKWgCM92wZp/7nxHZtSVcRERPE2V6thORZ48aTxubPizuYdoG7pdwt8ZGz4qhITEH1 yF4bxddl/R1KIb3/2vuRf9Pfdo1GkMem0q15HT9yQ1kgDq6miDrmAUMU9/34eVma0JsU SCgQ== X-Gm-Message-State: AOAM530XLdbsrOd8zOjoXDpjQVtyGkb08QdCmGLbJcwMeNNLgxZkXiWc k8lLGsuvsIKXVgfTrqtxtE1xInhWAsiShA== X-Google-Smtp-Source: ABdhPJwK+q9Ggo3sWp7d7crIXcWK5khXZu2whyTJi45nk9HdyQyARtPNihFKY0DeLGdZVdJa6l+4DQ== X-Received: by 2002:ac2:5e6c:: with SMTP id a12mr767940lfr.568.1603366656278; Thu, 22 Oct 2020 04:37:36 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id l16sm230972lfg.155.2020.10.22.04.37.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Oct 2020 04:37:35 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 299A5102F6D; Thu, 22 Oct 2020 14:37:35 +0300 (+03) Date: Thu, 22 Oct 2020 14:37:35 +0300 From: "Kirill A. Shutemov" To: Ira Weiny Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , David Rientjes , Andrea Arcangeli , Kees Cook , Will Drewry , "Edgecombe, Rick P" , "Kleen, Andi" , Liran Alon , Mike Rapoport , x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [RFCv2 08/16] KVM: Use GUP instead of copy_from/to_user() to access guest memory Message-ID: <20201022113735.ugfe6haxrd22oqjh@box> References: <20201020061859.18385-1-kirill.shutemov@linux.intel.com> <20201020061859.18385-9-kirill.shutemov@linux.intel.com> <20201020172944.GA165907@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201020172944.GA165907@iweiny-DESK2.sc.intel.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Oct 20, 2020 at 10:29:44AM -0700, Ira Weiny wrote: > On Tue, Oct 20, 2020 at 09:18:51AM +0300, Kirill A. Shutemov wrote: > > New helpers copy_from_guest()/copy_to_guest() to be used if KVM memory > > protection feature is enabled. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > include/linux/kvm_host.h | 4 ++ > > virt/kvm/kvm_main.c | 90 +++++++++++++++++++++++++++++++--------- > > 2 files changed, 75 insertions(+), 19 deletions(-) > > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index 05e3c2fb3ef7..380a64613880 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -504,6 +504,7 @@ struct kvm { > > struct srcu_struct irq_srcu; > > pid_t userspace_pid; > > unsigned int max_halt_poll_ns; > > + bool mem_protected; > > }; > > > > #define kvm_err(fmt, ...) \ > > @@ -728,6 +729,9 @@ void kvm_set_pfn_dirty(kvm_pfn_t pfn); > > void kvm_set_pfn_accessed(kvm_pfn_t pfn); > > void kvm_get_pfn(kvm_pfn_t pfn); > > > > +int copy_from_guest(void *data, unsigned long hva, int len, bool protected); > > +int copy_to_guest(unsigned long hva, const void *data, int len, bool protected); > > + > > void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache); > > int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset, > > int len); > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index cf88233b819a..a9884cb8c867 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -2313,19 +2313,70 @@ static int next_segment(unsigned long len, int offset) > > return len; > > } > > > > +int copy_from_guest(void *data, unsigned long hva, int len, bool protected) > > +{ > > + int offset = offset_in_page(hva); > > + struct page *page; > > + int npages, seg; > > + > > + if (!protected) > > + return __copy_from_user(data, (void __user *)hva, len); > > + > > + might_fault(); > > + kasan_check_write(data, len); > > + check_object_size(data, len, false); > > + > > + while ((seg = next_segment(len, offset)) != 0) { > > + npages = get_user_pages_unlocked(hva, 1, &page, 0); > > + if (npages != 1) > > + return -EFAULT; > > + memcpy(data, page_address(page) + offset, seg); > > + put_page(page); > > + len -= seg; > > + hva += seg; > > + offset = 0; > > Why is data not updated on each iteration? Ouch. I guess no caller actually steps over page boundary. Will fix. -- Kirill A. Shutemov