From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Date: Fri, 21 Jul 2023 15:33:15 -0700 Subject: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory In-Reply-To: <20230721222704.GJ25699@ls.amr.corp.intel.com> References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-13-seanjc@google.com> <20230721061314.3ls6stdawz53drv3@yy-desk-7060> <20230721222704.GJ25699@ls.amr.corp.intel.com> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Jul 21, 2023, Isaku Yamahata wrote: > On Fri, Jul 21, 2023 at 02:13:14PM +0800, > Yuan Yao wrote: > > > +static int kvm_gmem_error_page(struct address_space *mapping, struct page *page) > > > +{ > > > + struct list_head *gmem_list = &mapping->private_list; > > > + struct kvm_memory_slot *slot; > > > + struct kvm_gmem *gmem; > > > + unsigned long index; > > > + pgoff_t start, end; > > > + gfn_t gfn; > > > + > > > + filemap_invalidate_lock_shared(mapping); > > > + > > > + start = page->index; > > > + end = start + thp_nr_pages(page); > > > + > > > + list_for_each_entry(gmem, gmem_list, entry) { > > > + xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) { > > > + for (gfn = start; gfn < end; gfn++) { > > > > Why the start end range used as gfn here ? Math is hard? I almost always mess up these types of things, and then catch my bugs via tests. But I don't have tests for this particular flow... Which reminds me, we need tests for this :-) Hopefully error injection provides most of what we need? > > the page->index is offset of inode's page cache mapping and > > gmem address space, IIUC, gfn calculation should follow same > > way as kvm_gmem_invalidate_begin(). > > Also instead of sending signal multiple times, we can utilize lsb argument. As Vishal pointed out, this code shouldn't be sending signals in the first place. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4ABD3DDC2 for ; Fri, 21 Jul 2023 22:33:18 +0000 (UTC) Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-c6dd0e46a52so2399717276.2 for ; Fri, 21 Jul 2023 15:33:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=N3JmIIRFuucWrTRji2j76NW5FMl4jS4wLA3POQW0VLRrR4sFhmKgj7pRUj3gSs0yqe WZvjiVqpyglaAnq94LWefXiOIlgXr/PrbktD6W+TBAFf6s+alvi+gxgQyH8TNpVAsODx OCRkSmym8Xr89af+taUXT0Vhz6Xh0SqYzK++E+LxDlItaWIfk/xiv3hy/q9bOsyCLBei XOyxBMd+5ThifDUK6/o5f+QTqfW/eyfYM90Y+kU5f1e/gaMgZLzn2OVn9bd0Flf7Aat3 ovp2GWeXuTu2BrzRvrwJog7aZBAUD7Ob8wE6NUPaB8bQmPi6OopUS5w2j6M71SZpRLW7 K0fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=ZO9s7rShMu/g0GSW3S4u2SoEv6qYmgEoqk5bkpd/eZErzPhEM9CVj4VySTqHbN1E2Y zxSTclW3PIBrZrdGD4vjhGBN13KSSMzKftu7HFB246OvFozhEB8xBeBrJPxJXsktjdhd NiXZWpW0p/emk3u4LtlJYzUnr4JPpxxgJKduAhi5ojnUCA7SS6nWofOAgP7W3RchSRb6 4onnhnq4vewqlxx2lCAAdP53FiIyMTovy9zCoaF3d8XzAH1MyqLqX7cDQnEDboHbpndg BXBs9mj1dAegVJsD1ImswwHN4inw9BJZ8mptxIUxGgN86NEnb6fORn2M7fFNvdPdRTHB DCZw== X-Gm-Message-State: ABy/qLYsJaYzJukuu+TvbsDWKtWHUfKmZJS+3Lq2zYPwyVGgIXf3TcIB zhSK4cah49hnQdjjXYUFqQyAZQPq+dI= X-Google-Smtp-Source: APBJJlHilhePzxpErmYmDQimNKPr2Kn3t6yMJLQXIDH2a2VxS3jSVStiMTfJxkBt/UbXzPR1R9iVHrOiOZs= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:ce82:0:b0:d04:faa6:e62b with SMTP id x124-20020a25ce82000000b00d04faa6e62bmr11683ybe.6.1689978797172; Fri, 21 Jul 2023 15:33:17 -0700 (PDT) Date: Fri, 21 Jul 2023 15:33:15 -0700 In-Reply-To: <20230721222704.GJ25699@ls.amr.corp.intel.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-13-seanjc@google.com> <20230721061314.3ls6stdawz53drv3@yy-desk-7060> <20230721222704.GJ25699@ls.amr.corp.intel.com> Message-ID: Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory From: Sean Christopherson To: Isaku Yamahata Cc: Yuan Yao , Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" On Fri, Jul 21, 2023, Isaku Yamahata wrote: > On Fri, Jul 21, 2023 at 02:13:14PM +0800, > Yuan Yao wrote: > > > +static int kvm_gmem_error_page(struct address_space *mapping, struct page *page) > > > +{ > > > + struct list_head *gmem_list = &mapping->private_list; > > > + struct kvm_memory_slot *slot; > > > + struct kvm_gmem *gmem; > > > + unsigned long index; > > > + pgoff_t start, end; > > > + gfn_t gfn; > > > + > > > + filemap_invalidate_lock_shared(mapping); > > > + > > > + start = page->index; > > > + end = start + thp_nr_pages(page); > > > + > > > + list_for_each_entry(gmem, gmem_list, entry) { > > > + xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) { > > > + for (gfn = start; gfn < end; gfn++) { > > > > Why the start end range used as gfn here ? Math is hard? I almost always mess up these types of things, and then catch my bugs via tests. But I don't have tests for this particular flow... Which reminds me, we need tests for this :-) Hopefully error injection provides most of what we need? > > the page->index is offset of inode's page cache mapping and > > gmem address space, IIUC, gfn calculation should follow same > > way as kvm_gmem_invalidate_begin(). > > Also instead of sending signal multiple times, we can utilize lsb argument. As Vishal pointed out, this code shouldn't be sending signals in the first place. 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 23B3CEB64DD for ; Fri, 21 Jul 2023 22:33:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID: References:Mime-Version:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=jBtwPXs2V/erdVRqr1boDIwqLByyQxzazGBKE4tGCJI=; b=coGIZo8IM9ze4wP6UE7mj4ZM9K 3Bx1UseVPpNwYwcPsYQ/srfxf4K3IN+mS4iw7f7/SIjj2z0sb+/q8RRoR5mQdz3rONvwjSE4UgCTS P9PUNBEIxrhhDLi4Rz7TcV1rYA42AWvMqrh34y0hEeCoRvkwctBy4dQF5Xgv3tdcOeOCc8I3Th7Kx TO4u7CvgcWBrlM++xe2jmtSntf3tcc8nDpnKflIflHU4T/jQobwj2HTUC1xaL8yZie7ULGkl3JOEI 4MvY+EyCWsLtbHe5AkZYkPCcPFnCnP6gOsMYv83Cx1RYgQOJPVeKgi69X20toY/id/Jc0cGF9Jrsr UeYmxEvg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qMygc-00FHeK-1t; Fri, 21 Jul 2023 22:33:22 +0000 Received: from mail-yw1-x114a.google.com ([2607:f8b0:4864:20::114a]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qMygZ-00FHcL-0b for linux-riscv@lists.infradead.org; Fri, 21 Jul 2023 22:33:20 +0000 Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-57320c10635so24254017b3.3 for ; Fri, 21 Jul 2023 15:33:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=N3JmIIRFuucWrTRji2j76NW5FMl4jS4wLA3POQW0VLRrR4sFhmKgj7pRUj3gSs0yqe WZvjiVqpyglaAnq94LWefXiOIlgXr/PrbktD6W+TBAFf6s+alvi+gxgQyH8TNpVAsODx OCRkSmym8Xr89af+taUXT0Vhz6Xh0SqYzK++E+LxDlItaWIfk/xiv3hy/q9bOsyCLBei XOyxBMd+5ThifDUK6/o5f+QTqfW/eyfYM90Y+kU5f1e/gaMgZLzn2OVn9bd0Flf7Aat3 ovp2GWeXuTu2BrzRvrwJog7aZBAUD7Ob8wE6NUPaB8bQmPi6OopUS5w2j6M71SZpRLW7 K0fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=WxFNRisM/COOxcP1QJeVR/dUnZh/YLnvuOPxtifuKrFiZa+BpL0IlSvGVUpW3f/YPB myw5qQh86kJh1esh1mNr8o3WG17c5pkTncSi0rBlCPmhtW5z+O2i+WQ1JpCaBd5URxy+ BGICEaJLFiSukmOzw63UFGuxWn0DtrOCaBz+PL8u76HkKqBixEKHtPq3VIWv0wSqFNt0 j/dAkDOrk7N+9BFNhxFOOUlAs+N2efcve6BHPvGJarOPf7qom+RjtpCLeWdzTzivW7rj ffMi/6RGoVM1SV8xGA1DxWXSEBCnRHMuQ6sPQluHakV5fGnfMB0NMg+bzwtN3JkG+bmS 6cTQ== X-Gm-Message-State: ABy/qLa8Cjuv71MleMCoKl+APpy14HaD512DZ/9lWE6vE12uZ0xz6Alm 8dPxTj0kfXiX+y2n1+lnASti2AXSq0A= X-Google-Smtp-Source: APBJJlHilhePzxpErmYmDQimNKPr2Kn3t6yMJLQXIDH2a2VxS3jSVStiMTfJxkBt/UbXzPR1R9iVHrOiOZs= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:ce82:0:b0:d04:faa6:e62b with SMTP id x124-20020a25ce82000000b00d04faa6e62bmr11683ybe.6.1689978797172; Fri, 21 Jul 2023 15:33:17 -0700 (PDT) Date: Fri, 21 Jul 2023 15:33:15 -0700 In-Reply-To: <20230721222704.GJ25699@ls.amr.corp.intel.com> Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-13-seanjc@google.com> <20230721061314.3ls6stdawz53drv3@yy-desk-7060> <20230721222704.GJ25699@ls.amr.corp.intel.com> Message-ID: Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory From: Sean Christopherson To: Isaku Yamahata Cc: Yuan Yao , Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , "Kirill A . Shutemov" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230721_153319_226077_7059B851 X-CRM114-Status: GOOD ( 14.85 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, Jul 21, 2023, Isaku Yamahata wrote: > On Fri, Jul 21, 2023 at 02:13:14PM +0800, > Yuan Yao wrote: > > > +static int kvm_gmem_error_page(struct address_space *mapping, struct page *page) > > > +{ > > > + struct list_head *gmem_list = &mapping->private_list; > > > + struct kvm_memory_slot *slot; > > > + struct kvm_gmem *gmem; > > > + unsigned long index; > > > + pgoff_t start, end; > > > + gfn_t gfn; > > > + > > > + filemap_invalidate_lock_shared(mapping); > > > + > > > + start = page->index; > > > + end = start + thp_nr_pages(page); > > > + > > > + list_for_each_entry(gmem, gmem_list, entry) { > > > + xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) { > > > + for (gfn = start; gfn < end; gfn++) { > > > > Why the start end range used as gfn here ? Math is hard? I almost always mess up these types of things, and then catch my bugs via tests. But I don't have tests for this particular flow... Which reminds me, we need tests for this :-) Hopefully error injection provides most of what we need? > > the page->index is offset of inode's page cache mapping and > > gmem address space, IIUC, gfn calculation should follow same > > way as kvm_gmem_invalidate_begin(). > > Also instead of sending signal multiple times, we can utilize lsb argument. As Vishal pointed out, this code shouldn't be sending signals in the first place. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BCD5FEB64DD for ; Fri, 21 Jul 2023 22:34:16 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20221208 header.b=N3JmIIRF; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4R749L4lNpz3cYT for ; Sat, 22 Jul 2023 08:34:14 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20221208 header.b=N3JmIIRF; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=flex--seanjc.bounces.google.com (client-ip=2607:f8b0:4864:20::114a; helo=mail-yw1-x114a.google.com; envelope-from=3rqe7zaykdnqi40d926ee6b4.2ecb8dknff2-34lb8iji.epb01i.eh6@flex--seanjc.bounces.google.com; receiver=lists.ozlabs.org) Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4R748K3jPdz3bX5 for ; Sat, 22 Jul 2023 08:33:19 +1000 (AEST) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-573d70da2dcso24458287b3.1 for ; Fri, 21 Jul 2023 15:33:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=N3JmIIRFuucWrTRji2j76NW5FMl4jS4wLA3POQW0VLRrR4sFhmKgj7pRUj3gSs0yqe WZvjiVqpyglaAnq94LWefXiOIlgXr/PrbktD6W+TBAFf6s+alvi+gxgQyH8TNpVAsODx OCRkSmym8Xr89af+taUXT0Vhz6Xh0SqYzK++E+LxDlItaWIfk/xiv3hy/q9bOsyCLBei XOyxBMd+5ThifDUK6/o5f+QTqfW/eyfYM90Y+kU5f1e/gaMgZLzn2OVn9bd0Flf7Aat3 ovp2GWeXuTu2BrzRvrwJog7aZBAUD7Ob8wE6NUPaB8bQmPi6OopUS5w2j6M71SZpRLW7 K0fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=i2UQXA82ifgEOq49Ic+1CXAyanFc4ifxfpUgMxZw2Brz1srloJTJ1KfJA3C4zDdZXG WNeCXv7GX9T5L9kDE5FdRGYoCmHboyE4g20HAUSqBqfPzqRzIeZbExbXTf/G3/lVAvzS s6CWfFi0DwoV0NT5JOxkrSVXoOCVRZctSRqwCdxC46qmu68f61G/ayAHyf1SECBYcNTs NzFFDZP3u+Y0NTJoAJ+0WqOlGybRoeUXVggeauWBGdSAsQTmG1h6rzEuP1ZgTVECD5SP p9rVtk9Hd1RC/YHAOA1NmTQDBubYcJTx0eoORGY06dM6XJMZkxpC3HKVGhSDBaRBcuYU EKbQ== X-Gm-Message-State: ABy/qLYrV3wWPZKO11pLnzTHen2CpPf7hA9r9y3e/rpW116wbstoVBaL otWumMGsb+DYVp5YzWYW0nyPGQ8ohEM= X-Google-Smtp-Source: APBJJlHilhePzxpErmYmDQimNKPr2Kn3t6yMJLQXIDH2a2VxS3jSVStiMTfJxkBt/UbXzPR1R9iVHrOiOZs= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:ce82:0:b0:d04:faa6:e62b with SMTP id x124-20020a25ce82000000b00d04faa6e62bmr11683ybe.6.1689978797172; Fri, 21 Jul 2023 15:33:17 -0700 (PDT) Date: Fri, 21 Jul 2023 15:33:15 -0700 In-Reply-To: <20230721222704.GJ25699@ls.amr.corp.intel.com> Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-13-seanjc@google.com> <20230721061314.3ls6stdawz53drv3@yy-desk-7060> <20230721222704.GJ25699@ls.amr.corp.intel.com> Message-ID: Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory From: Sean Christopherson To: Isaku Yamahata Content-Type: text/plain; charset="us-ascii" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, David Hildenbrand , Yu Zhang , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Chao Peng , linux-riscv@lists.infradead.org, Marc Zyngier , Paul Moore , Huacai Chen , James Morris , "Matthew Wilcox \(Oracle\)" , Wang , Fuad Tabba , Jarkko Sakkinen , "Serge E. Hallyn" , Maciej Szmigiero , Albert Ou , Vlastimil Babka , Michael Roth , Ackerley Tng , Yuan Yao , Paul Walmsley , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Quentin Perret , Liam Merwick , linux-mips@vger.kernel.org, Oliver Upton , linux-security-module@vger.kernel.org, Palmer Dabbelt , kvm-riscv@lists.infradead.org, Anup Patel , linux-fsdevel@vger.kernel.org, Paolo Bonzini , Andrew Morton , Vishal Annapurve , linuxppc-dev@lists.ozlabs.org, "Kirill A . Shutemov" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Jul 21, 2023, Isaku Yamahata wrote: > On Fri, Jul 21, 2023 at 02:13:14PM +0800, > Yuan Yao wrote: > > > +static int kvm_gmem_error_page(struct address_space *mapping, struct page *page) > > > +{ > > > + struct list_head *gmem_list = &mapping->private_list; > > > + struct kvm_memory_slot *slot; > > > + struct kvm_gmem *gmem; > > > + unsigned long index; > > > + pgoff_t start, end; > > > + gfn_t gfn; > > > + > > > + filemap_invalidate_lock_shared(mapping); > > > + > > > + start = page->index; > > > + end = start + thp_nr_pages(page); > > > + > > > + list_for_each_entry(gmem, gmem_list, entry) { > > > + xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) { > > > + for (gfn = start; gfn < end; gfn++) { > > > > Why the start end range used as gfn here ? Math is hard? I almost always mess up these types of things, and then catch my bugs via tests. But I don't have tests for this particular flow... Which reminds me, we need tests for this :-) Hopefully error injection provides most of what we need? > > the page->index is offset of inode's page cache mapping and > > gmem address space, IIUC, gfn calculation should follow same > > way as kvm_gmem_invalidate_begin(). > > Also instead of sending signal multiple times, we can utilize lsb argument. As Vishal pointed out, this code shouldn't be sending signals in the first place. 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4E4C2C001DC for ; Fri, 21 Jul 2023 22:33:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID: References:Mime-Version:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=+hSmXSeZlBCZ0wdB7AjWZooWyJHIimbwfIEYTI5EaVI=; b=4/eZKBuRs3MlceU5whQCVvkfWQ yU2Z7iqL+iBw1/O+75cRY2BMgqbhEgKvxUqC1BT4Zuq2KK0Fs95B0TZLULxmONuLBTxht1Jk8NWe2 X1z7z1xtFT+N1107LNXP6BB+fckvnbrDa0LutReI7zEAnDXsV0CgHRhMOJpkybvkmC6szu7NAzUHD 6zvN4fXRvpw5QY60khHIR00zAeyAAtKTWPFaMfPKbjZ863jbnAp+xs5MOfciSJpRJQ48NJGHRiLb+ IuJo3usoCFW1wCyjr2GZXw6TlYyU2XE7JWozX3zWhQ6tr5WcYxS8b7i2roqsenfc4T+O+nSGuTmM/ 6J5apB+g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qMygd-00FHex-1P; Fri, 21 Jul 2023 22:33:23 +0000 Received: from mail-yw1-x1149.google.com ([2607:f8b0:4864:20::1149]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qMygZ-00FHcM-1I for linux-arm-kernel@lists.infradead.org; Fri, 21 Jul 2023 22:33:21 +0000 Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-57320c10635so24254007b3.3 for ; Fri, 21 Jul 2023 15:33:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=N3JmIIRFuucWrTRji2j76NW5FMl4jS4wLA3POQW0VLRrR4sFhmKgj7pRUj3gSs0yqe WZvjiVqpyglaAnq94LWefXiOIlgXr/PrbktD6W+TBAFf6s+alvi+gxgQyH8TNpVAsODx OCRkSmym8Xr89af+taUXT0Vhz6Xh0SqYzK++E+LxDlItaWIfk/xiv3hy/q9bOsyCLBei XOyxBMd+5ThifDUK6/o5f+QTqfW/eyfYM90Y+kU5f1e/gaMgZLzn2OVn9bd0Flf7Aat3 ovp2GWeXuTu2BrzRvrwJog7aZBAUD7Ob8wE6NUPaB8bQmPi6OopUS5w2j6M71SZpRLW7 K0fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689978797; x=1690583597; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7T9EVRBobAr4a8JPgfiIjIX72kF/VyhERBKOIDOEvTo=; b=Ag8acqbAHOK8zVz2oBM2bAY5fzp33NPFFqjsiUWshG6ZTR10upZerV4wjvFJzQmRk9 BwgZ6HcqQPYKpuyCmsuXR0VkHuyyfZRqTz2Drq1+HTo0xC96A2/f1pDWiQfwg5vyERkv ixDjqLcvuB3NyD+9F3Q4F2sSGxvOaC9jNfHBpUq/xdilbwOWPzD7jD8lMb6vdY2Bv48V pmEbq+6RS1caB2SGhsH1kdWMg4YKOElEvy+ejAg0lNNEvBOJ3ZJD91PWacXcO87FWdxt zo/6KnMzGX7J5h1ciC48PYqAaMVcfZ01E0nki52/2qodg4A2euHvm2ExCxklgGoYKkVB rZKQ== X-Gm-Message-State: ABy/qLaHQrRPI0MTacNCuCm9RGQqB5DF6Vqpt0NjfimF7ck9phzlQ9F3 BAwrx4DJ3DK2iBsQkaGrpwrYlSVKgVM= X-Google-Smtp-Source: APBJJlHilhePzxpErmYmDQimNKPr2Kn3t6yMJLQXIDH2a2VxS3jSVStiMTfJxkBt/UbXzPR1R9iVHrOiOZs= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:ce82:0:b0:d04:faa6:e62b with SMTP id x124-20020a25ce82000000b00d04faa6e62bmr11683ybe.6.1689978797172; Fri, 21 Jul 2023 15:33:17 -0700 (PDT) Date: Fri, 21 Jul 2023 15:33:15 -0700 In-Reply-To: <20230721222704.GJ25699@ls.amr.corp.intel.com> Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-13-seanjc@google.com> <20230721061314.3ls6stdawz53drv3@yy-desk-7060> <20230721222704.GJ25699@ls.amr.corp.intel.com> Message-ID: Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory From: Sean Christopherson To: Isaku Yamahata Cc: Yuan Yao , Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , "Kirill A . Shutemov" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230721_153319_437017_FCCA97C7 X-CRM114-Status: GOOD ( 16.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jul 21, 2023, Isaku Yamahata wrote: > On Fri, Jul 21, 2023 at 02:13:14PM +0800, > Yuan Yao wrote: > > > +static int kvm_gmem_error_page(struct address_space *mapping, struct page *page) > > > +{ > > > + struct list_head *gmem_list = &mapping->private_list; > > > + struct kvm_memory_slot *slot; > > > + struct kvm_gmem *gmem; > > > + unsigned long index; > > > + pgoff_t start, end; > > > + gfn_t gfn; > > > + > > > + filemap_invalidate_lock_shared(mapping); > > > + > > > + start = page->index; > > > + end = start + thp_nr_pages(page); > > > + > > > + list_for_each_entry(gmem, gmem_list, entry) { > > > + xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) { > > > + for (gfn = start; gfn < end; gfn++) { > > > > Why the start end range used as gfn here ? Math is hard? I almost always mess up these types of things, and then catch my bugs via tests. But I don't have tests for this particular flow... Which reminds me, we need tests for this :-) Hopefully error injection provides most of what we need? > > the page->index is offset of inode's page cache mapping and > > gmem address space, IIUC, gfn calculation should follow same > > way as kvm_gmem_invalidate_begin(). > > Also instead of sending signal multiple times, we can utilize lsb argument. As Vishal pointed out, this code shouldn't be sending signals in the first place. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel