From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: [PATCH v2] device-assignment: Reset device on system reset Date: Thu, 17 Mar 2011 15:24:31 -0600 Message-ID: <20110317212413.14852.67041.stgit@s20.home> References: <20110317192923.24889.79288.stgit@s20.home> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: alex.williamson@redhat.com, ddutile@redhat.com, chrisw@redhat.com, bernhard.kohl@nsn.com To: kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37977 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755613Ab1CQVYe (ORCPT ); Thu, 17 Mar 2011 17:24:34 -0400 In-Reply-To: <20110317192923.24889.79288.stgit@s20.home> Sender: kvm-owner@vger.kernel.org List-ID: On system reset, we currently try to quiesce DMA by clearing the command register. This assumes that nothing re-enables bus master support without first de-programming the device. Use a bigger hammer to help the guest not shoot itself by issuing a function reset via sysfs on each system reset. Signed-off-by: Alex Williamson --- v2: Fix segment support hw/device-assignment.c | 24 ++++++++++++++++++++++-- 1 files changed, 22 insertions(+), 2 deletions(-) diff --git a/hw/device-assignment.c b/hw/device-assignment.c index db82e73..4997b6e 100644 --- a/hw/device-assignment.c +++ b/hw/device-assignment.c @@ -1693,13 +1693,33 @@ static const VMStateDescription vmstate_assigned_device = { static void reset_assigned_device(DeviceState *dev) { - PCIDevice *d = DO_UPCAST(PCIDevice, qdev, dev); + PCIDevice *pci_dev = DO_UPCAST(PCIDevice, qdev, dev); + AssignedDevice *adev = DO_UPCAST(AssignedDevice, dev, pci_dev); + char reset_file[64]; + const char reset[] = "1"; + int fd, ret; + + snprintf(reset_file, sizeof(reset_file), + "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/reset", + adev->host.seg, adev->host.bus, adev->host.dev, adev->host.func); + + /* + * Issue a device reset via pci-sysfs. Note that we use write(2) here + * and ignore the return value because some kernels have a bug that + * returns 0 rather than bytes written on success, sending us into an + * infinite retry loop using other write mechanisms. + */ + fd = open(reset_file, O_WRONLY); + if (fd != -1) { + ret = write(fd, reset, strlen(reset)); + close(fd); + } /* * When a 0 is written to the command register, the device is logically * disconnected from the PCI bus. This avoids further DMA transfers. */ - assigned_dev_pci_write_config(d, PCI_COMMAND, 0, 2); + assigned_dev_pci_write_config(pci_dev, PCI_COMMAND, 0, 2); } static int assigned_initfn(struct PCIDevice *pci_dev)