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[99.241.198.116]) by smtp.gmail.com with ESMTPSA id m14-20020a05622a054e00b002e2072cffe6sm17042300qtx.5.2022.03.30.11.34.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 11:34:23 -0700 (PDT) Date: Wed, 30 Mar 2022 14:34:21 -0400 From: Peter Xu To: David Matlack Subject: Re: [PATCH v2 20/26] KVM: x86/mmu: Extend Eager Page Splitting to the shadow MMU Message-ID: References: <20220311002528.2230172-1-dmatlack@google.com> <20220311002528.2230172-21-dmatlack@google.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline 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 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);"? > > > > > > + *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 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 ADBC6C4332F for ; Wed, 30 Mar 2022 18:36:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350445AbiC3SiT (ORCPT ); Wed, 30 Mar 2022 14:38:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46140 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352834AbiC3SgN (ORCPT ); Wed, 30 Mar 2022 14:36:13 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 99DDC546BF for ; Wed, 30 Mar 2022 11:34:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1648665265; 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: in-reply-to:in-reply-to:references:references; bh=BO423QJpHjYuJkP0ZfVrkV5p4JcZ6+8e4Hhk2wmOLQ4=; b=irXBaQGlWjn8xxvUtHFR1Nx1ZqBp5AO3u9OgTUkkmW7UeQgaMNZvhYdHcAve+QWmVTpugk VLgpjhD1JgBNdSAK+Qc35RNbnZIVQaKO/CUa5P4MAKYXu2fZQvqA+qbr8fQfKE8yhyRW6j sk6YS/Yx0A7PNpOmsmU262X30YSsuuw= Received: from mail-qt1-f199.google.com (mail-qt1-f199.google.com [209.85.160.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-591-8D0b8JwbPMGSHveZUR0DqA-1; Wed, 30 Mar 2022 14:34:24 -0400 X-MC-Unique: 8D0b8JwbPMGSHveZUR0DqA-1 Received: by mail-qt1-f199.google.com with SMTP id t26-20020ac8739a000000b002e06aa03d4cso18052820qtp.13 for ; Wed, 30 Mar 2022 11:34:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=BO423QJpHjYuJkP0ZfVrkV5p4JcZ6+8e4Hhk2wmOLQ4=; b=IxHo3ZnZ8bOphu7ku9I+xi8TgsXe3PIjm8xkqyfNL+FhahS+mxBLlaPbQDDOa+VSXJ xYCJo9AdQVHYGi7cMrfOHDHwSXIQYOX9NSc8GMmwtlMFyd9RUT4VTbrBVZ9h3DPUasmo ww3aUfuC01buzn8fWwKV4wWfnpV+YvRIGPvHgQbKe9eV22mFjpuNPMnbxdICzrOlUK4s sgUwXBS3Fte5a2sRh5PxzZphY1eb+ud+xL+VjTIPisQyvb2DNCKpUcPviiVl8810RMcX GJjvXa+SuYc88KGv5ZMvVtPjz/k8CUQl01Ku5tAMVeren408NdYH3o1Jen+8mHrZllcv iiHw== X-Gm-Message-State: AOAM532vUiAgzyKQq9j1M6b32qmGmISrDtxwG00f8ZsuIPexSvW/EHDi uzxkHsCzaIIxfmbpsidBBAANS6g2ex9+v6zz4HRcmAE15RitHhJR1zSCOMXLkRKoa+s9NCFdx8z XfMP4OBih273u8jNqvhZtfQ== X-Received: by 2002:a05:6214:52:b0:440:f824:a7f3 with SMTP id c18-20020a056214005200b00440f824a7f3mr680784qvr.125.1648665263568; Wed, 30 Mar 2022 11:34:23 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwpEYagEUKrFreUNZJWPbgOd2iyA4mWjJAcuNj/S06/ZmWXmhH8bpHqRFw8Cg5TxB9Aa+BVhQ== X-Received: by 2002:a05:6214:52:b0:440:f824:a7f3 with SMTP id c18-20020a056214005200b00440f824a7f3mr680755qvr.125.1648665263302; Wed, 30 Mar 2022 11:34:23 -0700 (PDT) Received: from xz-m1.local (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id m14-20020a05622a054e00b002e2072cffe6sm17042300qtx.5.2022.03.30.11.34.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 11:34:23 -0700 (PDT) Date: Wed, 30 Mar 2022 14:34:21 -0400 From: Peter Xu To: David Matlack 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 Subject: Re: [PATCH v2 20/26] KVM: x86/mmu: Extend Eager Page Splitting to the shadow MMU Message-ID: References: <20220311002528.2230172-1-dmatlack@google.com> <20220311002528.2230172-21-dmatlack@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org 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);"? > > > > > > + *spp = kvm_mmu_alloc_direct_sp_for_split(true); > > > + if (r) > > > + goto drop_lock; > > > + > > > + return 0; Thanks, -- Peter Xu