From 1ab09b4a1a35f60a0c0efa5b04b0949336815e34 Mon Sep 17 00:00:00 2001
From: Alex Williamson <alex.williamson@redhat.com>
Date: Wed, 23 Mar 2011 22:25:38 -0300
Subject: [PATCH 2/2] device-assignment: Reset device on system reset

RH-Author: Alex Williamson <alex.williamson@redhat.com>
Message-id: <20110323222538.3292.28939.stgit@s20.home>
Patchwork-id: 20532
O-Subject: [RHEL5.7 qemu-kvm PATCH v2 2/2] device-assignment: Reset device on
	system reset
Bugzilla: 657149
RH-Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>
RH-Acked-by: Don Dutile <ddutile@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=657149
Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=3199413
Upstream status: posted (removed segment support and modified for backport)

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 <alex.williamson@redhat.com>
---

 qemu/hw/device-assignment.c |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 qemu/hw/device-assignment.c |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/qemu/hw/device-assignment.c b/qemu/hw/device-assignment.c
index 81076c6..560887b 100644
--- a/qemu/hw/device-assignment.c
+++ b/qemu/hw/device-assignment.c
@@ -1177,6 +1177,25 @@ out:
 static void reset_assigned_device(void *opaque)
 {
     AssignedDevInfo *adev = opaque;
+    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->bus, adev->dev, adev->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
-- 
1.7.4.1.230.gae447