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 E1088C433F5 for ; Thu, 31 Mar 2022 19:57:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241109AbiCaT7j (ORCPT ); Thu, 31 Mar 2022 15:59:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234812AbiCaT7i (ORCPT ); Thu, 31 Mar 2022 15:59:38 -0400 Received: from mail-lj1-x22f.google.com (mail-lj1-x22f.google.com [IPv6:2a00:1450:4864:20::22f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01B88216FB1 for ; Thu, 31 Mar 2022 12:57:51 -0700 (PDT) Received: by mail-lj1-x22f.google.com with SMTP id v12so1213945ljd.3 for ; Thu, 31 Mar 2022 12:57:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=pTe27Qc9aU9mrh9Xska5d8/rYGqxPk37jFPTpeO0UrM=; b=cM+XYBWkQOvd6IpcK95d5PqkmE8Zj/rsE4HM7KyzFR+6DlwGlrOGTFvjtZpdC9Aguj ESLCoJHA6QKBbqz7zUq2+E4v6HH/ZVXTMUYngj6O/43jTiLxBhJi3bfgeUXDEUrKXO08 jlLXoMJrlDu0ntHa4lYeB+e2z1Fh9359EEd57bYrB062nhgLtDMXJSITG9Z6Kf3Ed3Fi mthSWhv5B5HSBNA0vYd6c5UqJ/fLBKbFciLMVvj0n4okgDzj36jXxbYKZr9X1J8Auxr+ KBfDAEbrqLEltDXdCTGVk7I9BVY+6Ofz+qmkKRTQ2zs3SMS+MOlVbg/b0NYQ27XQppJ0 WsuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=pTe27Qc9aU9mrh9Xska5d8/rYGqxPk37jFPTpeO0UrM=; b=UmpGVzNE771vfN7+JvTBKp5RlO2x5DbREoe1EYnULWFB6SBGi9d4wzmrMYUDNpYH6n dVPNStvCIG2Fgigv1GYKBvj3YMVuyrMmSf2npArtkvwT0pvtrWtzUlZcsCf7bhNBC08X 6YoO1o3YHENBUQ1LPtQYElTuWOID74VhHiUsJaY3q7kcXzDM3b/K74k1U87THjSaPDwC sC9SgxFMcBX1fk473B3a/bez4xWp4bklduSyHg9UMDR4+WAGuoKU85ztXCvrI91WMhj8 VVXL2CeZjO1XJ/HBU2EYm69lgMilHTtURx9lLp3AzMbkraNKScv4gezNqw4e9jGNiTgw U1Mw== X-Gm-Message-State: AOAM532DBB+CU/4jzNPM7aZI5GaM5/hRoLL1xTY+XobDQcaznOWaHLw+ rO8wz2aqcv6AWwWGMKxcQmAd7xmJKhhxvlExiFSHaQ== X-Google-Smtp-Source: ABdhPJw9+gcr6sgJpKfiIcWS6ZH8RxhxtcabitgSKfJZiaZHQP81kNDhjMCQEcxa3zOxAKVi/mFm6Pv92XT19v/VvHs= X-Received: by 2002:a2e:390c:0:b0:248:1b88:d6c4 with SMTP id g12-20020a2e390c000000b002481b88d6c4mr11250384lja.49.1648756669056; Thu, 31 Mar 2022 12:57:49 -0700 (PDT) MIME-Version: 1.0 References: <20220311002528.2230172-1-dmatlack@google.com> <20220311002528.2230172-21-dmatlack@google.com> In-Reply-To: From: David Matlack Date: Thu, 31 Mar 2022 12:57:22 -0700 Message-ID: Subject: Re: [PATCH v2 20/26] KVM: x86/mmu: Extend Eager Page Splitting to the shadow MMU To: Peter Xu Cc: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Andrew Jones , Ben Gardon , "Maciej S. Szmigiero" , "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" , "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" , "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" , "open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)" , Peter Feiner Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Wed, Mar 30, 2022 at 11:34 AM Peter Xu wrote: > > On Tue, Mar 22, 2022 at 04:58:08PM -0700, David Matlack wrote: > > > > +static int prepare_to_split_huge_page(struct kvm *kvm, > > > > + const struct kvm_memory_slot *slot, > > > > + u64 *huge_sptep, > > > > + struct kvm_mmu_page **spp, > > > > + bool *flush, > > > > + bool *dropped_lock) > > > > +{ > > > > + int r = 0; > > > > + > > > > + *dropped_lock = false; > > > > + > > > > + if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) > > > > + return -ENOSPC; > > > > + > > > > + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) > > > > + goto drop_lock; > > > > + > > > > > > Not immediately clear on whether there'll be case that *spp is set within > > > the current function. Some sanity check might be nice? > > > > Sorry I'm not sure what you mean here. What kind of sanity check did > > you have in mind? > > Something like "WARN_ON_ONCE(*spp);"? Ah I see. I was confused because the previous version of this code checked if *spp is already set and, if so, skipped the allocation. But I accidentally introduced a memory leak here when I implemented Ben' suggestion to defer alloc_memory_for_split() to a subsequent commit. I'll fix this in v3. > > > > > > > > > > + *spp = kvm_mmu_alloc_direct_sp_for_split(true); > > > > + if (r) > > > > + goto drop_lock; > > > > + > > > > + return 0; > > Thanks, > > -- > Peter Xu > 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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 515B8C433F5 for ; Fri, 1 Apr 2022 16:24:14 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B0FF749E2C; Fri, 1 Apr 2022 12:24:13 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6HdUxxXgbhK1; Fri, 1 Apr 2022 12:24:12 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9303049E36; Fri, 1 Apr 2022 12:24:12 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 98E5C4B1A3 for ; Thu, 31 Mar 2022 15:57:51 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 17PaXb9kKAfc for ; Thu, 31 Mar 2022 15:57:50 -0400 (EDT) Received: from mail-lj1-f175.google.com (mail-lj1-f175.google.com [209.85.208.175]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 7CBBE4B1AB for ; Thu, 31 Mar 2022 15:57:50 -0400 (EDT) Received: by mail-lj1-f175.google.com with SMTP id s13so1201231ljd.5 for ; Thu, 31 Mar 2022 12:57:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=pTe27Qc9aU9mrh9Xska5d8/rYGqxPk37jFPTpeO0UrM=; b=cM+XYBWkQOvd6IpcK95d5PqkmE8Zj/rsE4HM7KyzFR+6DlwGlrOGTFvjtZpdC9Aguj ESLCoJHA6QKBbqz7zUq2+E4v6HH/ZVXTMUYngj6O/43jTiLxBhJi3bfgeUXDEUrKXO08 jlLXoMJrlDu0ntHa4lYeB+e2z1Fh9359EEd57bYrB062nhgLtDMXJSITG9Z6Kf3Ed3Fi mthSWhv5B5HSBNA0vYd6c5UqJ/fLBKbFciLMVvj0n4okgDzj36jXxbYKZr9X1J8Auxr+ KBfDAEbrqLEltDXdCTGVk7I9BVY+6Ofz+qmkKRTQ2zs3SMS+MOlVbg/b0NYQ27XQppJ0 WsuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=pTe27Qc9aU9mrh9Xska5d8/rYGqxPk37jFPTpeO0UrM=; b=IU8L2XR0bvzXHZvuFPiEYzTQ5afMe2QXIFMDcMN4nEFNxY8wCKSNgCrY9+TmLJL9kw NntOUH1M9wFinSlJXNVRmJhzx9sDqNY4cB37MZcxzxN8HoVIilY82LntQAWu4ysO7xZq BVBSnT+F0YAiVLXhc9es5+5/+m0VEJTUTic+T2N5tJacbq3zRv7RFBe9ZnTGDOBouu5V DF7qyuxxlI7cBsi4qiGPi+gDY5NwX9pkYATXUSyps5KJFTzWUzayM/P1tMr+XinEO47Z HOHKWikF598DHRiz3BuQqAYovxbaAtng76Fr6pY7J+USadq2Hvn9dXIaWEmP+4pZ/plI qpxw== X-Gm-Message-State: AOAM530n+0lq8/KBwqPlVT0RPbZ37SXuW3qixQzg7zuWYX6p0plhUacd YAKk3VB/IxEXRjBrbI5Uy+qD3mEZEiZTTQfp+KhkkA== X-Google-Smtp-Source: ABdhPJw9+gcr6sgJpKfiIcWS6ZH8RxhxtcabitgSKfJZiaZHQP81kNDhjMCQEcxa3zOxAKVi/mFm6Pv92XT19v/VvHs= X-Received: by 2002:a2e:390c:0:b0:248:1b88:d6c4 with SMTP id g12-20020a2e390c000000b002481b88d6c4mr11250384lja.49.1648756669056; Thu, 31 Mar 2022 12:57:49 -0700 (PDT) MIME-Version: 1.0 References: <20220311002528.2230172-1-dmatlack@google.com> <20220311002528.2230172-21-dmatlack@google.com> In-Reply-To: From: David Matlack Date: Thu, 31 Mar 2022 12:57:22 -0700 Message-ID: Subject: Re: [PATCH v2 20/26] KVM: x86/mmu: Extend Eager Page Splitting to the shadow MMU To: Peter Xu X-Mailman-Approved-At: Fri, 01 Apr 2022 12:24:11 -0400 Cc: Marc Zyngier , Albert Ou , "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" , Huacai Chen , "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" , Aleksandar Markovic , Palmer Dabbelt , "open list:KERNEL VIRTUAL MACHINE FOR RISC-V \(KVM/riscv\)" , Paul Walmsley , Ben Gardon , Paolo Bonzini , "Maciej S. Szmigiero" , "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 \(KVM/arm64\)" , Peter Feiner X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Wed, Mar 30, 2022 at 11:34 AM Peter Xu wrote: > > On Tue, Mar 22, 2022 at 04:58:08PM -0700, David Matlack wrote: > > > > +static int prepare_to_split_huge_page(struct kvm *kvm, > > > > + const struct kvm_memory_slot *slot, > > > > + u64 *huge_sptep, > > > > + struct kvm_mmu_page **spp, > > > > + bool *flush, > > > > + bool *dropped_lock) > > > > +{ > > > > + int r = 0; > > > > + > > > > + *dropped_lock = false; > > > > + > > > > + if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) > > > > + return -ENOSPC; > > > > + > > > > + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) > > > > + goto drop_lock; > > > > + > > > > > > Not immediately clear on whether there'll be case that *spp is set within > > > the current function. Some sanity check might be nice? > > > > Sorry I'm not sure what you mean here. What kind of sanity check did > > you have in mind? > > Something like "WARN_ON_ONCE(*spp);"? Ah I see. I was confused because the previous version of this code checked if *spp is already set and, if so, skipped the allocation. But I accidentally introduced a memory leak here when I implemented Ben' suggestion to defer alloc_memory_for_split() to a subsequent commit. I'll fix this in v3. > > > > > > > > > > + *spp = kvm_mmu_alloc_direct_sp_for_split(true); > > > > + if (r) > > > > + goto drop_lock; > > > > + > > > > + return 0; > > Thanks, > > -- > Peter Xu > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm