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=-5.1 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLACK autolearn=ham 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 3422AC04EBD for ; Tue, 16 Oct 2018 07:34:09 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 6E7FF20881 for ; Tue, 16 Oct 2018 07:34:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6E7FF20881 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=popple.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42Z6WK30kVzF3Vm for ; Tue, 16 Oct 2018 18:34:05 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=popple.id.au Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=popple.id.au (client-ip=150.101.137.145; helo=ipmail06.adl6.internode.on.net; envelope-from=alistair@popple.id.au; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=popple.id.au Received: from ipmail06.adl6.internode.on.net (ipmail06.adl6.internode.on.net [150.101.137.145]) by lists.ozlabs.org (Postfix) with ESMTP id 42Z6TB602jzF3PJ for ; Tue, 16 Oct 2018 18:32:14 +1100 (AEDT) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: A2BpBQCh299Z/3oKyHleGwEBAQMBAQEJAQEBgy8uZG4nhVmJNI4+AYF1LwGWDYIELYRJSQQCAoQ+WAECAQEBAQECayiFHgEFJxMcIxALDgoJFRAPASkeBhOKHRGtTjqLPAEBAQEBBQEBAQEfBYMthUKDKoQ/KgWGCwWhRIdejX6SHpckV4EOHBYYCQgZGYVjHBmBYiw2iSKCNQEBAQ Received: from 121-200-10-122.nbn.syd.aussiebb.net (HELO new-mexico.localnet) ([121.200.10.122]) by ipmail06.adl6.internode.on.net with ESMTP; 16 Oct 2018 18:02:14 +1030 From: Alistair Popple To: Alexey Kardashevskiy Subject: Re: [PATCH kernel v2] powerpc/ioda/npu: Call skiboot's hot reset hook when disabling NPU2 Date: Tue, 16 Oct 2018 18:32:10 +1100 Message-ID: <2086775.d8i5QI7OoB@new-mexico> User-Agent: KMail/5.2.3 (Linux/4.17.0-0.bpo.1-amd64; KDE/5.28.0; x86_64; ; ) In-Reply-To: <374a32c1-8787-2b82-af5d-163d9a496a25@ozlabs.ru> References: <20181002032021.7126-1-aik@ozlabs.ru> <2184134.UzzIe8q8zq@new-mexico> <374a32c1-8787-2b82-af5d-163d9a496a25@ozlabs.ru> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Reza Arbab , linuxppc-dev@lists.ozlabs.org, David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tuesday, 16 October 2018 1:22:53 PM AEDT Alexey Kardashevskiy wrote: > > On 16/10/2018 13:19, Alistair Popple wrote: > >> reset_ntl() does what npu2_dev_procedure_reset() does plus more stuff, > >> there nothing really in npu2_dev_procedure_reset() which reset_ntl() > >> does not do already from the hardware standpoint. And it did stop HMIs > >> for me though. > >> > >> but ok, what will be sufficient then if not reset_ntl()? > > > > Argh, yes you are correct. Specifically both npu2_dev_procedure_reset() and > > reset_ntl() contain: > > > > /* NTL Reset */ > > val = npu2_read(ndev->npu, NPU2_NTL_MISC_CFG1(ndev)); > > val |= PPC_BIT(8) | PPC_BIT(9); > > npu2_write(ndev->npu, NPU2_NTL_MISC_CFG1(ndev), val); > > > > Which should fence the brick. However from what I recall there was more to > > reliably preventing HMIs than merely fencing the brick. It invovled a sequence > > of fencing and flushing the cache with dcbf instructions at the right time which > > is why we also have the FLR. Unfortunately I don't know the precise details, > > perhaps if we send enough coffee Balbir's way he might be able remind us? > > > He suggested and ack'ed that skiboot patch, I can repeat beers^wcoffee > but it won't change much ;) Ha. Couldn't hurt ;) I was pretty sure flushing the caches was an important part of the sequence to avoid HMI's. I believe you are trying to deal with unexpected guest terminations which means the driver won't have a chance to flush the caches prior to termination so wouldn't you also need to do that somewhere? Unless the driver does it at startup? - Alistair > > > > - Alistair > > > >> > >> > >>> > >>> - Alistair > >>> > >>>> > >>>> > >>>> > >>>>> > >>>>> - Alistair > >>>>> > >>>>> On Monday, 15 October 2018 6:17:51 PM AEDT Alexey Kardashevskiy wrote: > >>>>>> Ping? > >>>>>> > >>>>>> > >>>>>> On 02/10/2018 13:20, Alexey Kardashevskiy wrote: > >>>>>>> The skiboot firmware has a hot reset handler which fences the NVIDIA V100 > >>>>>>> GPU RAM on Witherspoons and makes accesses no-op instead of throwing HMIs: > >>>>>>> https://github.com/open-power/skiboot/commit/fca2b2b839a67 > >>>>>>> > >>>>>>> Now we are going to pass V100 via VFIO which most certainly involves > >>>>>>> KVM guests which are often terminated without getting a chance to offline > >>>>>>> GPU RAM so we end up with a running machine with misconfigured memory. > >>>>>>> Accessing this memory produces hardware management interrupts (HMI) > >>>>>>> which bring the host down. > >>>>>>> > >>>>>>> To suppress HMIs, this wires up this hot reset hook to vfio_pci_disable() > >>>>>>> via pci_disable_device() which switches NPU2 to a safe mode and prevents > >>>>>>> HMIs. > >>>>>>> > >>>>>>> Signed-off-by: Alexey Kardashevskiy > >>>>>>> --- > >>>>>>> Changes: > >>>>>>> v2: > >>>>>>> * updated the commit log > >>>>>>> --- > >>>>>>> arch/powerpc/platforms/powernv/pci-ioda.c | 10 ++++++++++ > >>>>>>> 1 file changed, 10 insertions(+) > >>>>>>> > >>>>>>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c > >>>>>>> index cde7102..e37b9cc 100644 > >>>>>>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c > >>>>>>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c > >>>>>>> @@ -3688,6 +3688,15 @@ static void pnv_pci_release_device(struct pci_dev *pdev) > >>>>>>> pnv_ioda_release_pe(pe); > >>>>>>> } > >>>>>>> > >>>>>>> +static void pnv_npu_disable_device(struct pci_dev *pdev) > >>>>>>> +{ > >>>>>>> + struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev); > >>>>>>> + struct eeh_pe *eehpe = edev ? edev->pe : NULL; > >>>>>>> + > >>>>>>> + if (eehpe && eeh_ops && eeh_ops->reset) > >>>>>>> + eeh_ops->reset(eehpe, EEH_RESET_HOT); > >>>>>>> +} > >>>>>>> + > >>>>>>> static void pnv_pci_ioda_shutdown(struct pci_controller *hose) > >>>>>>> { > >>>>>>> struct pnv_phb *phb = hose->private_data; > >>>>>>> @@ -3732,6 +3741,7 @@ static const struct pci_controller_ops pnv_npu_ioda_controller_ops = { > >>>>>>> .reset_secondary_bus = pnv_pci_reset_secondary_bus, > >>>>>>> .dma_set_mask = pnv_npu_dma_set_mask, > >>>>>>> .shutdown = pnv_pci_ioda_shutdown, > >>>>>>> + .disable_device = pnv_npu_disable_device, > >>>>>>> }; > >>>>>>> > >>>>>>> static const struct pci_controller_ops pnv_npu_ocapi_ioda_controller_ops = { > >>>>>>> > >>>>>> > >>>>>> > >>>>> > >>>>> > >>>> > >>>> > >>> > >>> > >> > >> > > > > > >