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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D9B3C433F5 for ; Wed, 27 Oct 2021 06:25:55 +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 EE58760F38 for ; Wed, 27 Oct 2021 06:25:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EE58760F38 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.216664.376356 (Exim 4.92) (envelope-from ) id 1mfcN0-0005ns-VR; Wed, 27 Oct 2021 06:25:06 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 216664.376356; Wed, 27 Oct 2021 06:25:06 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mfcN0-0005nl-RT; Wed, 27 Oct 2021 06:25:06 +0000 Received: by outflank-mailman (input) for mailman id 216664; Wed, 27 Oct 2021 06:25:04 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mfcMy-0005nf-4L for xen-devel@lists.xenproject.org; Wed, 27 Oct 2021 06:25:04 +0000 Received: from bombadil.infradead.org (unknown [2607:7c80:54:e::133]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 4e021e22-7e4b-441f-b44e-752d004858ba; Wed, 27 Oct 2021 06:25:01 +0000 (UTC) Received: from [2001:8b0:10b:1::3ae] (helo=u3832b3a9db3152.ant.amazon.com) by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfcMm-0041Uh-76; Wed, 27 Oct 2021 06:24:52 +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 Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 4e021e22-7e4b-441f-b44e-752d004858ba DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=s9OIF1LOOIWjOap4Z+0ARv4jSisQpi6HR05O3fSLE9M=; b=OAZT0EUWtkHuAtwBiA+wcSAUyI gGocJo4lme1tgjUuASWjldzYn5n6TVObit2CZuHDfay5r0owhhP9VedNJWe5aggzimy9ZRtp6GW8r NXaY1I3sV4TwyAddfW7gBnCCdHuSwL6VdmFU2Y+TF+iUVR0ZH6K+OlVDf7Z38Vm5yC1GJirpGg1Kx UQiZkyE2Y1DUtEHCdYusJ0i5Rfy4X6k6GM8VCngu56rwARAXzWMM2tTeTeZvTDaI54w/qERPa3uBQ PLHl6FH5wJv+RlQc98v2Mimp/QkCc3vPmwcrZ0F1DZsi6p/fNwSujtfjryz+3KKcyER5meP2S3zuQ 3MjWwayQ==; Message-ID: Subject: Re: [PATCH v2] PCI/MSI: Re-add checks for skip masking MSI-X on Xen PV From: David Woodhouse To: Josef Johansson , Jason Andryuk , Marc Zyngier Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, xen-devel , Thomas Gleixner , Juergen Gross , Boris Ostrovsky Date: Wed, 27 Oct 2021 07:24:49 +0100 In-Reply-To: References: <20211019202906.GA2397931@bhelgaas> <5f050b30-fa1c-8387-0d6b-a667851b34b0@oderland.se> <877de7dfl2.wl-maz@kernel.org> <3434cb2d-4060-7969-d4c4-089c68190527@oderland.se> <90277228-cf14-0cfa-c95e-d42e7d533353@oderland.se> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-N2uIjvIfDePtsDUY+x3E" User-Agent: Evolution 3.36.5-0ubuntu1 MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html --=-N2uIjvIfDePtsDUY+x3E Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2021-10-25 at 21:21 +0200, Josef Johansson wrote: > + if (!(pci_msi_ignore_mask || entry->msi_attrib.is_virtual)) Is it just me, or is that a lot easier to read if you write it as the tautologically-identical (!pci_msi_ignore_mask && !entry->=E2=80=A6is_virtu= al)? > @@ -546,7 +548,8 @@ static int msi_capability_init(struct pci_dev *dev, i= nt nvec, > return -ENOMEM; > /* All MSIs are unmasked by default; mask them all * > - pci_msi_mask(entry, msi_multi_mask(entry)) > + if (!pci_msi_ignore_mask) > + pci_msi_mask(entry, msi_multi_mask(entry)); > > list_add_tail(&entry->list, dev_to_msi_list(&dev->dev)); Hm, I thought that older kernels *did* do this part (or at least the later ones in pci_msi*_hutdown). I was watching it when I did the Xen hosting implementation I mentioned before; even a hack to unmask them all when the VM was started, wasn't working because the guest would *mask* all MSI-X, just never unmask them again. I wonder if we should rename 'pci_msi_ignore_mask' to something with Xen in its name because Xen is the only user of this abomination (which fundamentally seems to require that the virtual hardware use MSI entries even while they're masked, so hopefully nobody else would *ever* do such a thing), and the required behaviour is very Xen- specific. --=-N2uIjvIfDePtsDUY+x3E Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B 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