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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 7CAB2C433ED for ; Thu, 22 Apr 2021 15:12:15 +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 2244B6143B for ; Thu, 22 Apr 2021 15:12:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2244B6143B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.115622.220647 (Exim 4.92) (envelope-from ) id 1lZazq-0000wq-8c; Thu, 22 Apr 2021 15:12:02 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 115622.220647; Thu, 22 Apr 2021 15:12:02 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZazq-0000wi-4y; Thu, 22 Apr 2021 15:12:02 +0000 Received: by outflank-mailman (input) for mailman id 115622; Thu, 22 Apr 2021 15:12:01 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lZazp-0000wV-2D for xen-devel@lists.xenproject.org; Thu, 22 Apr 2021 15:12:01 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id b6371d87-7a72-4d0b-a089-2107ba09d254; Thu, 22 Apr 2021 15:12:00 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4CF3FAF9E; Thu, 22 Apr 2021 15:11:59 +0000 (UTC) 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 Precedence: list Sender: "Xen-devel" X-Inumbo-ID: b6371d87-7a72-4d0b-a089-2107ba09d254 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1619104319; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KeHtsNUnNrQOFdXTPcryvONBYcXGdC+xExUWV7QRyJ4=; b=vNjbqCwWsbKXFW3OcrYkbDa0G6AGp7z4DRW2Dp8WDXPbc3WJVY+1GeIXDBzwjAjS+Tq2Ri 6ir5saZxZ5bGZvXfxYgivLav75sZCMr4d0veCl7tFQnzPmbU8jrJXOIm0ylo6q3eG/tN4V m0NzOBKxssnTEMZh0wwaqU8n8w7AglQ= Subject: Re: [PATCH v3 19/22] x86emul: support TILELOADD{,T1} and TILESTORE From: Jan Beulich To: Paul Durrant Cc: Andrew Cooper , George Dunlap , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , "xen-devel@lists.xenproject.org" References: <322de6db-e01f-0b57-5777-5d94a13c441a@suse.com> <6b604011-a618-871a-2a3e-9118dd1b702b@suse.com> Message-ID: Date: Thu, 22 Apr 2021 17:11:59 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <6b604011-a618-871a-2a3e-9118dd1b702b@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 22.04.2021 17:06, Jan Beulich wrote: > On 22.04.2021 16:55, Jan Beulich wrote: >> + do { >> + /* Limit rows to just as many to cover the next one to access. */ >> + cfg->start_row = i; >> + cfg->rows[modrm_reg] = i + 1; >> + write_tilecfg(cfg); >> + >> + if ( vex.pfx != vex_f3 ) >> + rc = ops->read(ea.mem.seg, >> + truncate_ea(ea.mem.off + i * ea.val), >> + row, cfg->colsb[modrm_reg], ctxt); >> + >> + invoke_stub("", "", "=m" (dummy) : "a" (row)); >> + >> + if ( vex.pfx == vex_f3 ) >> + rc = ops->write(ea.mem.seg, >> + truncate_ea(ea.mem.off + i * ea.val), >> + row, cfg->colsb[modrm_reg], ctxt); >> + } while ( rc == X86EMUL_OKAY && ++i < n ); > > in principle tiles could have rows larger than 64 bytes without any > separate CPUID feature flag qualifying this. struct hvm_mmio_cache, > otoh, is having a fixed-size 64-byte buffer right now. Therefore I'm > wondering whether we'd want to switch to dynamically allocating that > to the minimum of 64 bytes and the size of a tile row, just as a > precautionary measure. Actually, as it occurred to me only after sending, enlarging tile size would under almost all circumstances require a new XSTATE component, which we'd need to enable first. I consider it less likely that they'd permit a wider range of layouts without increasing tile size. But we might still want to play safe. Jan