Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752597AbbFQWbm (ORCPT ); Wed, 17 Jun 2015 18:31:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46765 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752258AbbFQWbg (ORCPT ); Wed, 17 Jun 2015 18:31:36 -0400 Message-ID: <1434580294.5628.135.camel@redhat.com> Subject: Re: [PATCH v4 0/4] VFIO platform reset From: Alex Williamson To: Eric Auger Cc: eric.auger@st.com, linux-arm-kernel@lists.infradead.org, b.reynal@virtualopensystems.com, linux-kernel@vger.kernel.org, patches@linaro.org, christoffer.dall@linaro.org Date: Wed, 17 Jun 2015 16:31:34 -0600 In-Reply-To: <1434359385-19916-1-git-send-email-eric.auger@linaro.org> References: <1434359385-19916-1-git-send-email-eric.auger@linaro.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4518 Lines: 114 On Mon, 2015-06-15 at 11:09 +0200, Eric Auger wrote: > In situations where the userspace driver is stopped abnormally and the > VFIO platform device is released, the assigned HW device currently is > left running. As a consequence the HW device might continue issuing IRQs > and performing DMA accesses. > > On release, no physical IRQ handler is setup anymore. Also the DMA buffers > are unmapped leading to IOMMU aborts. So there is no serious consequence. > > However when assigning that HW device again to another userspace driver, > this latter might face some unexpected IRQs and DMA accesses, which are > the result of the previous assignment. > > In virtualization use-case, a VM newly granted with that HW device may be > impacted by the assignment of that device to a previous VM: > - IRQs may be injected very early when booting the new guest, even before > the guest driver has initialized leading to possible driver state > inconsistency. > - DMA accesses may hit the newly mapped VM address space at addresses that > may jeopardize the integrity of the newly installed VM. > > Obviously the criticity depends on the assigned HW device. > > As opposed to PCI, there is no standard mechanism to reset the platform > device. > > This series proposes to implement device specific reset functions in > separate in-kernel vfio reset modules. The vfio-platform driver holds > a whitelist of implemented triplets (compat string, module name, > reset function name). When the vfio-platform driver is probed it identifies > the fellow reset module/function matching the compat string of the > device, if any, and forces the load of this reset module. > > A first reset module is provided: the vfio-platform-calxedaxgmac > module which implements a basic reset for the Calxeda xgmac. > > The series can be found at > https://git.linaro.org/people/eric.auger/linux.git/shortlog/refs/heads/v4.1-rc8-reset-v4 > > History: > v3 -> v4: > - fix the commit message of "VFIO: platform: add reset struct and lookup table" Baptiste, Any comments? Should we also add something like this to MAINTAINERS before we go much further? diff --git a/MAINTAINERS b/MAINTAINERS index d8afd29..c6bf7f6 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -10545,6 +10545,12 @@ F: drivers/vfio/ F: include/linux/vfio.h F: include/uapi/linux/vfio.h +VFIO PLATFORM DRIVER +M: Baptiste Reynal +L: kvm@vger.kernel.org +S: Maintained +F: drivers/vfio/platform/ + VIDEOBUF2 FRAMEWORK M: Pawel Osciak M: Marek Szyprowski I'm not sure what you want to be the primary list, maybe it's time to ask for a vfio list. Thanks, Alex > > v2 -> v3: > - remove void module_init/exit functions in calxeda reset module > - remove enum vfio_platform_reset_type > - for reset lookup, use ARRAY_SIZE > - in reset put use symbol_put_addr > > v1 -> v2: > - much simplified compared to v1 although principle of external modules is > kept: removed mechanism of dynamic registration of reset functions > - list is replaced by whitelist lookup table > - name of the reset function also stored in the lookup table > - autoload of reset modules > > RFC -> PATCH v1: > - solution now based on a lookup list instead of specialized driver > > > Eric Auger (4): > VFIO: platform: add reset struct and lookup table > VFIO: platform: add reset callback > VFIO: platform: populate the reset function on probe > VFIO: platform: Calxeda xgmac reset module > > drivers/vfio/platform/Kconfig | 2 + > drivers/vfio/platform/Makefile | 2 + > drivers/vfio/platform/reset/Kconfig | 7 ++ > drivers/vfio/platform/reset/Makefile | 5 ++ > .../platform/reset/vfio_platform_calxedaxgmac.c | 86 ++++++++++++++++++++++ > drivers/vfio/platform/vfio_platform_common.c | 60 ++++++++++++++- > drivers/vfio/platform/vfio_platform_private.h | 7 ++ > 7 files changed, 166 insertions(+), 3 deletions(-) > create mode 100644 drivers/vfio/platform/reset/Kconfig > create mode 100644 drivers/vfio/platform/reset/Makefile > create mode 100644 drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/