From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S939499AbeE1O5I (ORCPT ); Mon, 28 May 2018 10:57:08 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:43570 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S937078AbeE1OzA (ORCPT ); Mon, 28 May 2018 10:55:00 -0400 Subject: Re: [PATCH v2] vfio: platform: Fix using devices in PM Domains To: Geert Uytterhoeven , Alex Williamson References: <1526640912-894-1-git-send-email-geert+renesas@glider.be> Cc: kvm@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org From: Auger Eric Message-ID: <10a503da-d431-f2c9-3ddc-91b065563a0d@redhat.com> Date: Mon, 28 May 2018 16:54:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1526640912-894-1-git-send-email-geert+renesas@glider.be> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Geert, On 05/18/2018 12:55 PM, Geert Uytterhoeven wrote: > If a device is part of a PM Domain (e.g. power and/or clock domain), its > power state is managed using Runtime PM. Without Runtime PM, the device > may not be powered up or clocked, causing subtle failures, crashes, or > system lock-ups when the device is accessed by the guest. > > Fix this by adding Runtime PM support, powering the device when the VFIO > device is opened by the guest. I fail to apply this on master branch? > > Note that while more fine-grained power management could be implemented > on the guest side, if exported by the host, this would be inherently > unsafe, as abusing it may take down the whole system. I think I would prefer we get rid of the above paragraph. Thanks Eric > > Signed-off-by: Geert Uytterhoeven > Reviewed-by: Simon Horman > --- > v2: > - Improve wording, > - Add Reviewed-by. > --- > drivers/vfio/platform/vfio_platform_common.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c > index b60bb5326668498c..41f862f055054543 100644 > --- a/drivers/vfio/platform/vfio_platform_common.c > +++ b/drivers/vfio/platform/vfio_platform_common.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -233,6 +234,8 @@ static void vfio_platform_release(void *device_data) > const char *extra_dbg = NULL; > int ret; > > + pm_runtime_put(vdev->device); > + > ret = vfio_platform_call_reset(vdev, &extra_dbg); > if (ret && vdev->reset_required) { > dev_warn(vdev->device, "reset driver is required and reset call failed in release (%d) %s\n", > @@ -275,6 +278,10 @@ static int vfio_platform_open(void *device_data) > ret, extra_dbg ? extra_dbg : ""); > goto err_rst; > } > + > + ret = pm_runtime_get_sync(vdev->device); > + if (ret < 0) > + goto err_rst; > } > > vdev->refcnt++; > @@ -690,6 +697,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev, > > mutex_init(&vdev->igate); > > + pm_runtime_enable(vdev->device); > return 0; > > put_iommu: > @@ -707,6 +715,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev) > vdev = vfio_del_group_dev(dev); > > if (vdev) { > + pm_runtime_disable(vdev->device); > vfio_platform_put_reset(vdev); > vfio_iommu_group_put(dev->iommu_group, dev); > } >