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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 6DF48C282CE for ; Tue, 4 Jun 2019 16:11:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5211A20843 for ; Tue, 4 Jun 2019 16:11:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728269AbfFDQLq (ORCPT ); Tue, 4 Jun 2019 12:11:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:32772 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728178AbfFDQLp (ORCPT ); Tue, 4 Jun 2019 12:11:45 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E301D2F8BDD; Tue, 4 Jun 2019 16:11:21 +0000 (UTC) Received: from [10.36.116.67] (ovpn-116-67.ams2.redhat.com [10.36.116.67]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C5C836064C; Tue, 4 Jun 2019 16:11:09 +0000 (UTC) Subject: Re: [PATCH v8 26/29] vfio-pci: Register an iommu fault handler To: Alex Williamson Cc: eric.auger.pro@gmail.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, joro@8bytes.org, jacob.jun.pan@linux.intel.com, yi.l.liu@intel.com, jean-philippe.brucker@arm.com, will.deacon@arm.com, robin.murphy@arm.com, kevin.tian@intel.com, ashok.raj@intel.com, marc.zyngier@arm.com, peter.maydell@linaro.org, vincent.stehle@arm.com References: <20190526161004.25232-1-eric.auger@redhat.com> <20190526161004.25232-27-eric.auger@redhat.com> <20190603163139.70fe8839@x1.home> From: Auger Eric Message-ID: <10dd60d9-4af0-c0eb-08c9-a0db7ee1925e@redhat.com> Date: Tue, 4 Jun 2019 18:11:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190603163139.70fe8839@x1.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 04 Jun 2019 16:11:44 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hi Alex, On 6/4/19 12:31 AM, Alex Williamson wrote: > On Sun, 26 May 2019 18:10:01 +0200 > Eric Auger wrote: > >> This patch registers a fault handler which records faults in >> a circular buffer and then signals an eventfd. This buffer is >> exposed within the fault region. >> >> Signed-off-by: Eric Auger >> >> --- >> >> v3 -> v4: >> - move iommu_unregister_device_fault_handler to vfio_pci_release >> --- >> drivers/vfio/pci/vfio_pci.c | 49 +++++++++++++++++++++++++++++ >> drivers/vfio/pci/vfio_pci_private.h | 1 + >> 2 files changed, 50 insertions(+) >> >> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c >> index f75f61127277..520999994ba8 100644 >> --- a/drivers/vfio/pci/vfio_pci.c >> +++ b/drivers/vfio/pci/vfio_pci.c >> @@ -30,6 +30,7 @@ >> #include >> #include >> #include >> +#include >> >> #include "vfio_pci_private.h" >> >> @@ -296,6 +297,46 @@ static const struct vfio_pci_regops vfio_pci_fault_prod_regops = { >> .add_capability = vfio_pci_fault_prod_add_capability, >> }; >> >> +int vfio_pci_iommu_dev_fault_handler(struct iommu_fault_event *evt, void *data) >> +{ >> + struct vfio_pci_device *vdev = (struct vfio_pci_device *) data; >> + struct vfio_region_fault_prod *prod_region = >> + (struct vfio_region_fault_prod *)vdev->fault_pages; >> + struct vfio_region_fault_cons *cons_region = >> + (struct vfio_region_fault_cons *)(vdev->fault_pages + 2 * PAGE_SIZE); >> + struct iommu_fault *new = >> + (struct iommu_fault *)(vdev->fault_pages + prod_region->offset + >> + prod_region->prod * prod_region->entry_size); >> + int prod, cons, size; >> + >> + mutex_lock(&vdev->fault_queue_lock); >> + >> + if (!vdev->fault_abi) >> + goto unlock; >> + >> + prod = prod_region->prod; >> + cons = cons_region->cons; >> + size = prod_region->nb_entries; >> + >> + if (CIRC_SPACE(prod, cons, size) < 1) >> + goto unlock; >> + >> + *new = evt->fault; >> + prod = (prod + 1) % size; >> + prod_region->prod = prod; >> + mutex_unlock(&vdev->fault_queue_lock); >> + >> + mutex_lock(&vdev->igate); >> + if (vdev->dma_fault_trigger) >> + eventfd_signal(vdev->dma_fault_trigger, 1); >> + mutex_unlock(&vdev->igate); >> + return 0; >> + >> +unlock: >> + mutex_unlock(&vdev->fault_queue_lock); >> + return -EINVAL; >> +} >> + >> static int vfio_pci_init_fault_region(struct vfio_pci_device *vdev) >> { >> struct vfio_region_fault_prod *header; >> @@ -328,6 +369,13 @@ static int vfio_pci_init_fault_region(struct vfio_pci_device *vdev) >> header = (struct vfio_region_fault_prod *)vdev->fault_pages; >> header->version = -1; >> header->offset = PAGE_SIZE; >> + >> + ret = iommu_register_device_fault_handler(&vdev->pdev->dev, >> + vfio_pci_iommu_dev_fault_handler, >> + vdev); >> + if (ret) >> + goto out; >> + >> return 0; >> out: >> kfree(vdev->fault_pages); >> @@ -570,6 +618,7 @@ static void vfio_pci_release(void *device_data) >> if (!(--vdev->refcnt)) { >> vfio_spapr_pci_eeh_release(vdev->pdev); >> vfio_pci_disable(vdev); >> + iommu_unregister_device_fault_handler(&vdev->pdev->dev); > > > But this can fail if there are pending faults which leaves a device > reference and then the system is broken :( This series only features unrecoverable errors and for those the unregistration cannot fail. Now unrecoverable errors were added I admit this is confusing. We need to sort this out or clean the dependencies. Thanks Eric > >> } >> >> mutex_unlock(&vdev->reflck->lock); >> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h >> index 8e0a55682d3f..a9276926f008 100644 >> --- a/drivers/vfio/pci/vfio_pci_private.h >> +++ b/drivers/vfio/pci/vfio_pci_private.h >> @@ -122,6 +122,7 @@ struct vfio_pci_device { >> int ioeventfds_nr; >> struct eventfd_ctx *err_trigger; >> struct eventfd_ctx *req_trigger; >> + struct eventfd_ctx *dma_fault_trigger; >> struct mutex fault_queue_lock; >> int fault_abi; >> struct list_head dummy_resources_list; >