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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 87EA7C4320A for ; Thu, 26 Aug 2021 16:56:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74B4B60F6F for ; Thu, 26 Aug 2021 16:56:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243154AbhHZQ52 (ORCPT ); Thu, 26 Aug 2021 12:57:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:53092 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229986AbhHZQ51 (ORCPT ); Thu, 26 Aug 2021 12:57:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B280260F42; Thu, 26 Aug 2021 16:56:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629997000; bh=Sdch8X0otKtSPDpNPDcyA2dbJPDXupeY4yKkLojSNgM=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=PLpHEoTX8XMr7eS8sKDfSN7Wk21t5UKFAtp72cb2VF8bPUtYS3Te3k2zc69ABLQHF LEUWCG9EdTEoJS3PaRxPY045Fm1iRpbSehFQP+7TC8hlyMcRErMgAgFO/V/fsmH0QR KCDXJqQMf+YvkCH/FS95duDi82JSMmr0nHqYgSzsrtMPU3VQld/xBUf3tEfALHco8v /8fb4PB3ps5MmsOS60KQ1eEAW+RJ8rz3lYKdRAmlpIxh6rCzKOpISemkcF9pRnnxjC Tfwh3GuxflCERNdOFpY/1PWMCakkDhhUxorzIrQu4Js/bqAlA9Y6fcm5i4E70ucWLW wYJX9y1kW54tg== Date: Thu, 26 Aug 2021 11:56:38 -0500 From: Bjorn Helgaas To: Marek =?iso-8859-1?Q?Marczykowski-G=F3recki?= Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, xen-devel@lists.xenproject.org, Bjorn Helgaas , Marc Zyngier , Thomas Gleixner , "open list:PCI SUBSYSTEM" Subject: Re: [PATCH] PCI/MSI: skip masking MSI on Xen PV Message-ID: <20210826165638.GA3686936@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 26, 2021 at 06:36:49PM +0200, Marek Marczykowski-Górecki wrote: > On Thu, Aug 26, 2021 at 09:55:32AM -0500, Bjorn Helgaas wrote: > > If/when you repost this, please run "git log --oneline > > drivers/pci/msi.c" and follow the convention of capitalizing the > > subject line. > > > > Also, I think this patch refers specifically to MSI-X, not MSI, so > > please update the subject line and the "masking MSI" below to reflect > > that. > > Sure, thanks for pointing this out. Is the patch otherwise ok? Should I > post v2 with just updated commit message? Wouldn't hurt to post a v2. I don't have any objections to the patch, but ultimately up to Thomas. > > On Thu, Aug 26, 2021 at 03:43:37PM +0200, Marek Marczykowski-Górecki wrote: > > > When running as Xen PV guest, masking MSI is a responsibility of the > > > hypervisor. Guest has no write access to relevant BAR at all - when it > > > tries to, it results in a crash like this: > > > > > > BUG: unable to handle page fault for address: ffffc9004069100c > > > #PF: supervisor write access in kernel mode > > > #PF: error_code(0x0003) - permissions violation > > > PGD 18f1c067 P4D 18f1c067 PUD 4dbd067 PMD 4fba067 PTE 80100000febd4075 > > > Oops: 0003 [#1] SMP NOPTI > > > CPU: 0 PID: 234 Comm: kworker/0:2 Tainted: G W 5.14.0-rc7-1.fc32.qubes.x86_64 #15 > > > Workqueue: events work_for_cpu_fn > > > RIP: e030:__pci_enable_msix_range.part.0+0x26b/0x5f0 > > > Code: 2f 96 ff 48 89 44 24 28 48 89 c7 48 85 c0 0f 84 f6 01 00 00 45 0f b7 f6 48 8d 40 0c ba 01 00 00 00 49 c1 e6 04 4a 8d 4c 37 1c <89> 10 48 83 c0 10 48 39 c1 75 f5 41 0f b6 44 24 6a 84 c0 0f 84 48 > > > RSP: e02b:ffffc9004018bd50 EFLAGS: 00010212 > > > RAX: ffffc9004069100c RBX: ffff88800ed412f8 RCX: ffffc9004069105c > > > RDX: 0000000000000001 RSI: 00000000000febd4 RDI: ffffc90040691000 > > > RBP: 0000000000000003 R08: 0000000000000000 R09: 00000000febd404f > > > R10: 0000000000007ff0 R11: ffff88800ee8ae40 R12: ffff88800ed41000 > > > R13: 0000000000000000 R14: 0000000000000040 R15: 00000000feba0000 > > > FS: 0000000000000000(0000) GS:ffff888018400000(0000) knlGS:0000000000000000 > > > CS: e030 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: ffff8000007f5ea0 CR3: 0000000012f6a000 CR4: 0000000000000660 > > > Call Trace: > > > e1000e_set_interrupt_capability+0xbf/0xd0 [e1000e] > > > e1000_probe+0x41f/0xdb0 [e1000e] > > > local_pci_probe+0x42/0x80 > > > (...) > > > > > > There is pci_msi_ignore_mask variable for bypassing MSI masking on Xen > > > PV, but msix_mask_all() missed checking it. Add the check there too. > > > > > > Fixes: 7d5ec3d36123 ("PCI/MSI: Mask all unused MSI-X entries") > > > Cc: stable@vger.kernel.org > > > > 7d5ec3d36123 appeared in v5.14-rc6, so if this fix is merged before > > v5.14, the stable tag will be unnecessary. But we are running out of > > time there. > > 7d5ec3d36123 was already backported to stable branches (at least 5.10 > and 5.4), and in fact this is how I discovered the issue... Oh, right, of course. Sorry :) > > > Signed-off-by: Marek Marczykowski-Górecki > > > --- > > > Cc: xen-devel@lists.xenproject.org > > > --- > > > drivers/pci/msi.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > > > index e5e75331b415..3a9f4f8ad8f9 100644 > > > --- a/drivers/pci/msi.c > > > +++ b/drivers/pci/msi.c > > > @@ -776,6 +776,9 @@ static void msix_mask_all(void __iomem *base, int tsize) > > > u32 ctrl = PCI_MSIX_ENTRY_CTRL_MASKBIT; > > > int i; > > > > > > + if (pci_msi_ignore_mask) > > > + return; > > > + > > > for (i = 0; i < tsize; i++, base += PCI_MSIX_ENTRY_SIZE) > > > writel(ctrl, base + PCI_MSIX_ENTRY_VECTOR_CTRL); > > > } > > > -- > > > 2.31.1 > > > > > -- > Best Regards, > Marek Marczykowski-Górecki > Invisible Things Lab