From 064b752454fa2d672c72c34e1b300b854dd27bba Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Fri, 18 Mar 2011 19:35:33 -0300 Subject: [PATCH 2/2] device-assignment: Reset device on system reset RH-Author: Alex Williamson Message-id: <20110318193532.12086.39418.stgit@s20.home> Patchwork-id: 20277 O-Subject: [RHEL6.1 qemu-kvm PATCH 2/2] device-assignment: Reset device on system reset Bugzilla: 685147 RH-Acked-by: Michael S. Tsirkin RH-Acked-by: Don Dutile RH-Acked-by: Chris Wright Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=685147 Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=3188279 Upstream commit: posted (modified for lack of seg support in rhel) 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 Acked-by: Chris Wright --- hw/device-assignment.c | 24 ++++++++++++++++++++++-- 1 files changed, 22 insertions(+), 2 deletions(-) Signed-off-by: Luiz Capitulino --- 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 ad8826e..8a70f66 100644 --- a/hw/device-assignment.c +++ b/hw/device-assignment.c @@ -1651,13 +1651,33 @@ 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/0000:%02x:%02x.%01x/reset", + 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) -- 1.7.4.1.230.gae447