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=-8.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable 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 07242C4363D for ; Wed, 7 Oct 2020 12:31:39 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 0CCA72075A for ; Wed, 7 Oct 2020 12:31:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dTTMBDcW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0CCA72075A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55870 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kQ8bY-00070X-IR for qemu-devel@archiver.kernel.org; Wed, 07 Oct 2020 08:31:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41634) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kQ8V4-0003e7-8J for qemu-devel@nongnu.org; Wed, 07 Oct 2020 08:24:54 -0400 Received: from merlin.infradead.org ([2001:8b0:10b:1231::1]:54970) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kQ8Uz-0004md-Lv for qemu-devel@nongnu.org; Wed, 07 Oct 2020 08:24:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Mime-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=U8VmA2Keu5/rG5KZ3bHjiFADTpvcpSFILV2OPuuYX7A=; b=dTTMBDcWCXOVNn9VnEHlIrndp3 utrrEjMvYXjyAO4s1L5oKBnV7juSKkIEcF2MAMefy/6F3TB+wfTC693pHfdGyW7//qQwKBrt2x67W J0HiIQ+FT6KrAnX70vA9Zcyox9/6dHZoyVeOzJMC4bVyqaWAwg/L25hGdgYR7g2IkEIUdGtzxAJt9 i3FJSkvpt6pCse99DKZQFwydfXPRwVfltMpK5UqCR7yVN97/l/JyAtHluGB73a3jz4v69ckODZe4k xLBpiEOulXLbvdk5ww6oIsbW2Uo7u6Vre6KSqIRx2tfAz/Lt450PminlTX9I3qp+xQfnoO+srw8AE 82/+DGEA==; Received: from [54.239.6.188] (helo=freeip.amazon.com) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQ8Us-0008IN-0B; Wed, 07 Oct 2020 12:24:42 +0000 Message-ID: Subject: Re: [PATCH] target/i386: Support up to 32768 CPUs without IRQ remapping From: David Woodhouse To: qemu-devel Date: Wed, 07 Oct 2020 13:24:40 +0100 In-Reply-To: <78097f9218300e63e751e077a0a5ca029b56ba46.camel@infradead.org> References: <78097f9218300e63e751e077a0a5ca029b56ba46.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-IHtKFbVdnuRF0cbADVcN" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Received-SPF: none client-ip=2001:8b0:10b:1231::1; envelope-from=BATV+b14ff27a642ffd52eab2+6254+infradead.org+dwmw2@merlin.srs.infradead.org; helo=merlin.infradead.org X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , x86 , kvm Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --=-IHtKFbVdnuRF0cbADVcN Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2020-10-05 at 15:18 +0100, David Woodhouse wrote: > The IOAPIC has an 'Extended Destination ID' field in its RTE, which maps > to bits 11-4 of the MSI address. Since those address bits fall within a > given 4KiB page they were historically non-trivial to use on real hardwar= e. >=20 > The Intel IOMMU uses the lowest bit to indicate a remappable format MSI, > and then the remaining 7 bits are part of the index. >=20 > Where the remappable format bit isn't set, we can actually use the other > seven to allow external (IOAPIC and MSI) interrupts to reach up to 32768 > CPUs instead of just the 255 permitted on bare metal. >=20 > Signed-off-by: David Woodhouse Corresponding kernel patch at=20 https://patchwork.kernel.org/patch/11820535/ --=-IHtKFbVdnuRF0cbADVcN Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG 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