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 8F6C9C433B4 for ; Thu, 29 Apr 2021 09:40:19 +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 2281461445 for ; Thu, 29 Apr 2021 09:40:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2281461445 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.119854.226599 (Exim 4.92) (envelope-from ) id 1lc39T-0006OJ-7B; Thu, 29 Apr 2021 09:40:07 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 119854.226599; Thu, 29 Apr 2021 09:40:07 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lc39T-0006OC-2D; Thu, 29 Apr 2021 09:40:07 +0000 Received: by outflank-mailman (input) for mailman id 119854; Thu, 29 Apr 2021 09:40:05 +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 1lc39R-0006BD-JS for xen-devel@lists.xenproject.org; Thu, 29 Apr 2021 09:40:05 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 93005f52-26b4-41a4-a676-e4cd29567c9d; Thu, 29 Apr 2021 09:40:04 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9FD95B018; Thu, 29 Apr 2021 09:40:03 +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: 93005f52-26b4-41a4-a676-e4cd29567c9d 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=1619689203; 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=vahH0cyhzgCAdu5nMA3Vm4iCr2LnlAjH9wZJn6cLx9I=; b=SOfrPhyqXARHNLVeopc75SXTUMHVwUkpF/MLEXKOgLncsFODqnBkBhfmGMqcPGMGuuc6Gq wg9AzlNVTBFjYRtVJXc+l7B8H5EFXA28XXiWQ50wTZ9r5RRR5mk1hOjNF6ZRs9yHn45EUH a8FOD8zuK9fZ1jseCE+TZugmEBLzmok= Subject: Re: [PATCH v3 19/22] x86emul: support TILELOADD{,T1} and TILESTORE To: paul@xen.org References: <322de6db-e01f-0b57-5777-5d94a13c441a@suse.com> <6b604011-a618-871a-2a3e-9118dd1b702b@suse.com> <3c1d6f14-b091-6244-0ef0-3925601c770d@xen.org> Cc: xen-devel@lists.xenproject.org From: Jan Beulich Message-ID: <4f129a52-06ce-ab14-3e70-a7c78b64d344@suse.com> Date: Thu, 29 Apr 2021 11:40:02 +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: <3c1d6f14-b091-6244-0ef0-3925601c770d@xen.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 26.04.2021 09:12, Paul Durrant wrote: > On 22/04/2021 16:11, Jan Beulich wrote: >> 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. >> > > I guess on-demand reallocation to a larger size would be fine. Certainly > we want to be sure we don't overflow. Okay, I've added a patch doing not just this, but (perhaps even more important) also increase struct hvmemul_cache's capacity on such hardware. Jan