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.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 22A42C47077 for ; Thu, 11 Jan 2024 14:23:31 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.666309.1036842 (Exim 4.92) (envelope-from ) id 1rNvxh-0001oh-7B; Thu, 11 Jan 2024 14:23:13 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 666309.1036842; Thu, 11 Jan 2024 14:23:13 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rNvxh-0001oa-4c; Thu, 11 Jan 2024 14:23:13 +0000 Received: by outflank-mailman (input) for mailman id 666309; Thu, 11 Jan 2024 14:23:11 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rNvxf-0001oP-Pd for xen-devel@lists.xenproject.org; Thu, 11 Jan 2024 14:23:11 +0000 Received: from smtp-fw-9102.amazon.com (smtp-fw-9102.amazon.com [207.171.184.29]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id f0ce3b57-b08c-11ee-9b0f-b553b5be7939; Thu, 11 Jan 2024 15:23:09 +0100 (CET) Received: from pdx4-co-svc-p1-lb2-vlan3.amazon.com (HELO email-inbound-relay-iad-1d-m6i4x-25ac6bd5.us-east-1.amazon.com) ([10.25.36.214]) by smtp-border-fw-9102.sea19.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2024 14:22:58 +0000 Received: from smtpout.prod.us-east-1.prod.farcaster.email.amazon.dev (iad7-ws-svc-p70-lb3-vlan2.iad.amazon.com [10.32.235.34]) by email-inbound-relay-iad-1d-m6i4x-25ac6bd5.us-east-1.amazon.com (Postfix) with ESMTPS id B12BD49E36; Thu, 11 Jan 2024 14:22:56 +0000 (UTC) Received: from EX19MTAEUB001.ant.amazon.com [10.0.17.79:19433] by smtpin.naws.eu-west-1.prod.farcaster.email.amazon.dev [10.0.8.110:2525] with esmtp (Farcaster) id 632d1ee3-a123-4d46-9a96-0de918162ce9; Thu, 11 Jan 2024 14:22:55 +0000 (UTC) Received: from EX19D018EUA002.ant.amazon.com (10.252.50.146) by EX19MTAEUB001.ant.amazon.com (10.252.51.28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Thu, 11 Jan 2024 14:22:55 +0000 Received: from [10.95.99.82] (10.95.99.82) by EX19D018EUA002.ant.amazon.com (10.252.50.146) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Thu, 11 Jan 2024 14:22:52 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Inumbo-ID: f0ce3b57-b08c-11ee-9b0f-b553b5be7939 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1704982989; x=1736518989; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=UxX0msj9qVYm6nkqZ3EN4+ZCgnzvJVmxqtKw5NxCdY0=; b=u/w+V5AcN1toP0g7ULMdh6nHPCwE+Ay9ec/h/hxyoB2bWOPNn+RPojls 6XD3JqkbPW/17PP6dEZudPRwXXyPm5zMnBjqhAx0A+D7tP2irzmZnrrIR mb9rmbXpvmfpYpNXVzf8vdYW7f1conzTXGTOcQtGemb07VHZBxErPgo77 o=; X-IronPort-AV: E=Sophos;i="6.04,186,1695686400"; d="scan'208";a="389156229" X-Farcaster-Flow-ID: 632d1ee3-a123-4d46-9a96-0de918162ce9 Message-ID: <686fa772-486b-4878-a605-85b021e06058@amazon.com> Date: Thu, 11 Jan 2024 14:22:48 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 14/22] x86/domain_page: remove the fast paths when mfn is not in the directmap Content-Language: en-US To: Jan Beulich , Julien Grall CC: Hongyan Xia , Andrew Cooper , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Wei Liu , Julien Grall , References: <20221216114853.8227-1-julien@xen.org> <20221216114853.8227-15-julien@xen.org> <52429554-1559-6bae-f3d9-d32152e763b4@suse.com> From: Elias El Yandouzi In-Reply-To: <52429554-1559-6bae-f3d9-d32152e763b4@suse.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.95.99.82] X-ClientProxiedBy: EX19D046UWB004.ant.amazon.com (10.13.139.164) To EX19D018EUA002.ant.amazon.com (10.252.50.146) Precedence: Bulk Hi Jan, On 11/01/2023 14:11, Jan Beulich wrote: > As to using pmap - assuming you've done an audit and the number of > simultaneous mappings that can be in use can be proven to not exceed > the number of slots available, can you please say so in the description? I don't know if any audit has been made but a similar code has been internally used for a few years now without any problem. Quickly looking at the slots usage, I found that at most only 4 slots out of 8 would be used during boot time. > I have to admit though that I'm wary - this isn't a per-CPU number of > slots aiui, but a global one. But then you also have a BUG_ON() there > restricting the use to early boot. The reasoning for this is also > missing (and might address my concern). Indeed, this isn't presented as a per-CPU number of slots, but the slots can be only used before we reach the state SYS_STATE_smp_boot. So effectively, only the BSP would use the PMAP slots. The PMAP slots are meant to map at most the number of level page-tables. See the comment on top of NUM_FIX_PMAP definition. -- Elias