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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E456C54FCB for ; Thu, 23 Apr 2020 16:34:30 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 06E0320728 for ; Thu, 23 Apr 2020 16:34:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06E0320728 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jRenX-0001oR-1v; Thu, 23 Apr 2020 16:33:59 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jRenV-0001oM-4Z for xen-devel@lists.xenproject.org; Thu, 23 Apr 2020 16:33:57 +0000 X-Inumbo-ID: 39c495b6-8580-11ea-b4f4-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 39c495b6-8580-11ea-b4f4-bc764e2007e4; Thu, 23 Apr 2020 16:33:56 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 9C1B7ABCF; Thu, 23 Apr 2020 16:33:54 +0000 (UTC) Subject: Re: [PATCH v11 1/3] x86/tlb: introduce a flush HVM ASIDs flag To: Roger Pau Monne References: <20200423145611.55378-1-roger.pau@citrix.com> <20200423145611.55378-2-roger.pau@citrix.com> From: Jan Beulich Message-ID: <59e48d80-8ce1-3f3d-c07e-5117adea272a@suse.com> Date: Thu, 23 Apr 2020 18:33:49 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200423145611.55378-2-roger.pau@citrix.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: xen-devel@lists.xenproject.org, Tim Deegan , George Dunlap , Wei Liu , Andrew Cooper Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 23.04.2020 16:56, Roger Pau Monne wrote: > Introduce a specific flag to request a HVM guest linear TLB flush, > which is an ASID/VPID tickle that forces a guest linear to guest > physical TLB flush for all HVM guests. > > This was previously unconditionally done in each pre_flush call, but > that's not required: HVM guests not using shadow don't require linear > TLB flushes as Xen doesn't modify the pages tables the guest runs on > in that case (ie: when using HAP). Note that shadow paging code > already takes care of issuing the necessary flushes when the shadow > page tables are modified. > > In order to keep the previous behavior modify all shadow code TLB > flushes to also flush the guest linear to physical TLB if the guest is > HVM. I haven't looked at each specific shadow code TLB flush in order > to figure out whether it actually requires a guest TLB flush or not, > so there might be room for improvement in that regard. > > Also perform ASID/VPID flushes when modifying the p2m tables as it's a > requirement for AMD hardware. Finally keep the flush in > switch_cr3_cr4, as it's not clear whether code could rely on > switch_cr3_cr4 also performing a guest linear TLB flush. A following > patch can remove the ASID/VPID tickle from switch_cr3_cr4 if found to > not be necessary. > > Signed-off-by: Roger Pau Monné Reviewed-by: Jan Beulich