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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 2720EC3A5A1 for ; Mon, 21 Nov 2022 15:26:50 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 96AD610E2FA; Mon, 21 Nov 2022 15:26:28 +0000 (UTC) Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7B3FA10E1AF for ; Sat, 12 Nov 2022 00:43:12 +0000 (UTC) Received: by mail-pg1-x52b.google.com with SMTP id q1so5597619pgl.11 for ; Fri, 11 Nov 2022 16:43:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=W/69SGTblteqzTGqi+tKsPG0LW4tOtiDqnrFyQWptaQ=; b=nkkHJRYG9RSNUubkLNubrJI/d3KOEidZrgmUPThr3GFsr7fra6VsI+pb1qqQQ02WKX zF1WmMPVXJP4zWYv5H2yrK2XmJWXLyIYGleBrctfrNS+0hqbbCZ/iqh9/fdMvnZajEwa S7yTODLsbBcMwXwbemvi9xcCSHrHJ12nb+aTQowsorgnzkj19FB9Krp7KBYJxZyP21EO 7pIoX7pjC6wc+oSETXDUqR/kq2X+LicMr3aKFzkyce/50iVQxoQgCThUjuJ/3KLMl8+B z6LnADkM+0e/zYQoLtoBvelqEGFYq3NJyiIEmKpY5AR6UOQqXPItQJPmeuPg0YF/+hoh Qb/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=W/69SGTblteqzTGqi+tKsPG0LW4tOtiDqnrFyQWptaQ=; b=Z/rtFTRe0HoJ+Kri2OUNvw2jhQArx+oWny1WWGZTTzVd7M8Sdv5tJPF/BcDg/qff2g B/5HRwPMDqAEbtBW6V065vLn6+H9v/2SJX3wkoCQaeoePpjOPKEmp0wi4g5WlJy4End7 nIX5IRWSLcH2NnsUtW8NXlLF18HX8dCRVKdGo3BIy5bGiGzmsxRCw3dwwvBSd2J5Cm7o mMgH4EEkAtTWGcpQsjOYdZYU7OauySNT92ew0Yn0YpOdr6ERPCW1g8w50qZA7yD/cnGp FZk9xzdcDMEaaZJOTsjvZ5QwSedzoXOZ9yxBkiTMxrc3msoVHKF7bcCZCysDplB8hUMb AhLQ== X-Gm-Message-State: ANoB5pkGiROoxAxaz4xTiw+/ImQcija96/oO06/oqQxJgbeqNqPjEepB bQOPdnGQs/3PQDtlBdNX6pWoIA== X-Google-Smtp-Source: AA0mqf4WsOfrQhaQruL4asl5Iu86noh/aH6GkJDdmp/AzA4oKTD7iRzggslPFH8j54SEF3nTst7kQA== X-Received: by 2002:a62:838f:0:b0:56c:8b7:f2dc with SMTP id h137-20020a62838f000000b0056c08b7f2dcmr5095877pfe.16.1668213791697; Fri, 11 Nov 2022 16:43:11 -0800 (PST) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id o127-20020a625a85000000b0056bc9294e1asm2154927pfb.24.2022.11.11.16.43.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Nov 2022 16:43:11 -0800 (PST) Date: Sat, 12 Nov 2022 00:43:07 +0000 From: Sean Christopherson To: Yan Zhao Message-ID: References: <20221111103247.22275-1-yan.y.zhao@intel.com> <20221111103350.22326-1-yan.y.zhao@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Mon, 21 Nov 2022 15:26:24 +0000 Subject: Re: [Intel-gfx] [PATCH v2 1/3] KVM: x86: add a new page track hook track_remove_slot X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, intel-gvt-dev@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Sat, Nov 12, 2022, Yan Zhao wrote: > And I'm also not sure if a slots_arch_lock is required for > kvm_slot_page_track_add_page() and kvm_slot_page_track_remove_page(). It's not required. slots_arch_lock protects interaction between memslot updates mmu_first_shadow_root_alloc(). When CONFIG_KVM_EXTERNAL_WRITE_TRACKING=y, then the mmu_first_shadow_root_alloc() doesn't touch the memslots because everything is pre-allocated: bool kvm_page_track_write_tracking_enabled(struct kvm *kvm) { return IS_ENABLED(CONFIG_KVM_EXTERNAL_WRITE_TRACKING) || !tdp_enabled || kvm_shadow_root_allocated(kvm); } int kvm_page_track_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot, unsigned long npages) { if (!kvm_page_track_write_tracking_enabled(kvm)) <== always true return 0; return __kvm_page_track_write_tracking_alloc(slot, npages); } Though now that you point it out, it's tempting to #ifdef out some of those hooks so that's basically impossible for mmu_first_shadow_root_alloc() to cause problems. Not sure the extra #ideffery would be worth while though. slots_arch_lock also protects shadow_root_allocated, but that's a KVM-internal detail that isn't relevant to the page-tracking machinery when CONFIG_KVM_EXTERNAL_WRITE_TRACKING=y.