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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 C897FC433ED for ; Wed, 14 Apr 2021 21:04:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB49C61132 for ; Wed, 14 Apr 2021 21:04:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230254AbhDNVEX (ORCPT ); Wed, 14 Apr 2021 17:04:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:55566 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230350AbhDNVEO (ORCPT ); Wed, 14 Apr 2021 17:04:14 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1C30060240; Wed, 14 Apr 2021 21:03:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618434232; bh=cgcS4OT2OQ9yztrLDGKDqC6WZcpOr+I4kBHjkeeifHI=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=RyyQi/TmEIUBU+HOZ21LdL23oaLp2hBjZuOmAPFhhbi8qfzcfRIBmL6v1bCTQArTY coseRP6wrzY78lz0d9FYncNFhxNPVvXo+7KuJWIGGJsJt2e4lMfvKuHXJ0CY/OIBz5 afSssNEzxZjBR0nEBGWAzZ0OhZRrCypnVzy6z3AH0nQROcwvILiTdGgEm/5e/RGFWs hdAKI+cBjORjkgsJ3MM05L6PWYIo+mjU0tzfFU0/QWGKVZm3AFj+iZo7PhyKOjy+lH SEUZ4clOsj/5gZGs3oPzTOqzfhvL1rJl8KJpjm4kc7BYYEC6iU1el7OKYSLshEMRvk 64bdHZhw9OMJA== Date: Wed, 14 Apr 2021 16:03:50 -0500 From: Bjorn Helgaas To: Ingmar Klein Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Alex Williamson Subject: Re: QCA6174 pcie wifi: Add pci quirks Message-ID: <20210414210350.GA2537653@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <08982e05-b6e8-5a8d-24ab-da1488ee50a8@web.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [+cc Alex] On Fri, Apr 09, 2021 at 11:26:33AM +0200, Ingmar Klein wrote: > Edit: Retry, as I did not consider, that my mail-client would make this > party html. > > Dear maintainers, > I recently encountered an issue on my Proxmox server system, that > includes a Qualcomm QCA6174 m.2 PCIe wifi module. > https://deviwiki.com/wiki/AIRETOS_AFX-QCA6174-NX > > On system boot and subsequent virtual machine start (with passed-through > QCA6174), the VM would just freeze/hang, at the point where the ath10k > driver loads. > Quick search in the proxmox related topics, brought me to the following > discussion, which suggested a PCI quirk entry for the QCA6174 in the kernel: > https://forum.proxmox.com/threads/pcie-passthrough-freezes-proxmox.27513/ > > I then went ahead, got the Proxmox kernel source (v5.4.106) and applied > the attached patch. > Effect was as hoped, that the VM hangs are now gone. System boots and > runs as intended. > > Judging by the existing quirk entries for Atheros, I would think, that > my proposed "fix" could be included in the vanilla kernel. > As far as I saw, there is no entry yet, even in the latest kernel sources. This would need a signed-off-by; see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?id=v5.11#n361 This is an old issue, and likely we'll end up just applying this as yet another quirk. But looking at c3e59ee4e766 ("PCI: Mark Atheros AR93xx to avoid bus reset"), where it started, it seems to be connected to 425c1b223dac ("PCI: Add Virtual Channel to save/restore support"). I'd like to dig into that a bit more to see if there are any clues. AFAIK Linux itself still doesn't use VC at all, and 425c1b223dac added a fair bit of code. I wonder if we're restoring something out of order or making some simple mistake in the way to restore VC config. > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > index 706f27a86a8e..ecfe80ec5b9c 100644 > --- a/drivers/pci/quirks.c > +++ b/drivers/pci/quirks.c > @@ -3584,6 +3584,7 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0032, quirk_no_bus_reset); > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003c, quirk_no_bus_reset); > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0033, quirk_no_bus_reset); > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0034, quirk_no_bus_reset); > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003e, quirk_no_bus_reset); > > /* > * Root port on some Cavium CN8xxx chips do not successfully complete a bus