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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 923A8C433FF for ; Tue, 13 Aug 2019 19:14:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69E6D20665 for ; Tue, 13 Aug 2019 19:14:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mGZu1L4U" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726465AbfHMTOo (ORCPT ); Tue, 13 Aug 2019 15:14:44 -0400 Received: from mail-pl1-f193.google.com ([209.85.214.193]:38319 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726303AbfHMTOn (ORCPT ); Tue, 13 Aug 2019 15:14:43 -0400 Received: by mail-pl1-f193.google.com with SMTP id m12so11044673plt.5; Tue, 13 Aug 2019 12:14:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition :user-agent; bh=DfaDqPxiZMNZIbjsgNm0UGrK6HEhpQEX5jhA59JEvVg=; b=mGZu1L4UmgRrdfLrcBt65H8WlaGjVqPf6hmI3iKS3BEHrG04CR+SIlyc/snB3GFpnQ vZCBxE8IVRufoJL800Mk/F1qMWc5Vy82hWnKqJ5uLOGHkZSslTpy/S1vyYAXwU94N8l+ SIRY/lUnbTREy3ktiakmQ06cjhAsoo3dK4YUktGLrXpxEyH1i+g64KRwP07RvO4V90k4 mH6YqNc25+W3rdO63XMT/YrQNNmwbrLJoU4v1Tz4gOAoeApKAY6qnicKuyH8fl8IhvUU C2hsmxZaro3ZW4RcEPv/bftiAQ8aG2hDA2FNDnxnnVtY0M4dIwEwO5JuhFyIHekcERy0 mLMA== 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:mime-version :content-disposition:user-agent; bh=DfaDqPxiZMNZIbjsgNm0UGrK6HEhpQEX5jhA59JEvVg=; b=HoSskEokR1RVgnAzCmXtJ+D1Zw/0qEiIe7+HfXzUmr2aYps/JxRPW59Ptxtw8Lyp/K O53T3mL6S/vIhh8naA92vkXAI7OY+V8b+03UKCocyoFTwO2y/b2ef6LjqtPc6uRCMuft prKZ4Yt8hXSaPucQibYerAd7NT5FRZKbEAs8s41wUvM5rKOXF+Bs5Wbrh6DmkqB+XQI4 jt4wAIC/nGPIwzMwdbfWdQFL3obHugGmhCkV3Oa54jdweOmSz6KLZbWZELfVdNj4gVV5 wMlL2ZTfxkE3pES9j4/5Fdr8ASZf0th/5WRb9khC6wrFuQwa+hgsyJR2sKoyZ8714jRE A8HQ== X-Gm-Message-State: APjAAAXNRvAwsAL7rpCmJ6LETpSBOXxBEr3uqzt1IIQUYL8wTIigku8l /LFYYcjz871pj40wS5yYD+Z2/0m3 X-Google-Smtp-Source: APXvYqwS3DgaAm4+vLvXAZ9Zeo7tempzemZdQsTbxW4zTwntlSTwtllhm6sBWPklubMkYQGCbwWwmA== X-Received: by 2002:a17:902:bc41:: with SMTP id t1mr8526868plz.171.1565723683044; Tue, 13 Aug 2019 12:14:43 -0700 (PDT) Received: from bharath12345-Inspiron-5559 ([103.110.42.34]) by smtp.gmail.com with ESMTPSA id i126sm130247051pfb.32.2019.08.13.12.14.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Aug 2019 12:14:42 -0700 (PDT) Date: Wed, 14 Aug 2019 00:44:35 +0530 From: Bharath Vedartham To: pbonzini@redhat.com, rkrcmar@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, khalid.aziz@oracle.com Subject: [Question-kvm] Can hva_to_pfn_fast be executed in interrupt context? Message-ID: <20190813191435.GB10228@bharath12345-Inspiron-5559> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi all, I was looking at the function hva_to_pfn_fast(in virt/kvm/kvm_main) which is executed in an atomic context(even in non-atomic context, since hva_to_pfn_fast is much faster than hva_to_pfn_slow). My question is can this be executed in an interrupt context? The motivation for this question is that in an interrupt context, we cannot assume "current" to be the task_struct of the process of interest. __get_user_pages_fast assume current->mm when walking the process page tables. So if this function hva_to_pfn_fast can be executed in an interrupt context, it would not be safe to retrive the pfn with __get_user_pages_fast. Thoughts on this? Thank you Bharath