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From 742bae4cea60c8601bbb6e5ec643167d8ca664d7 Mon Sep 17 00:00:00 2001
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From: Nigel Croxon <ncroxon@redhat.com>
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Date: Tue, 6 Aug 2013 19:52:04 +0200
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Subject: vfio: QEMU-AER: Qemu changes to support AER for VFIO-PCI devices
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RH-Author: Nigel Croxon <ncroxon@redhat.com>
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Message-id: <1375818724-41239-3-git-send-email-ncroxon@redhat.com>
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Patchwork-id: 53017
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O-Subject: [RHEL7.0 qemu-kvm PATCH v2 2/2] vfio: QEMU-AER: Qemu changes to support AER for VFIO-PCI devices
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Bugzilla: 984604
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Alex Williamson <alex.williamson@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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From: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
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Add support for error containment when a VFIO device assigned to a KVM
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guest encounters an error. This is for PCIe devices/drivers that support AER
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functionality. When the host OS is notified of an error in a device either
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through the firmware first approach or through an interrupt handled by the AER
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root port driver, the error handler registered by the vfio-pci driver gets
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invoked. The qemu process is signaled through an eventfd registered per
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VFIO device by the qemu process. In the eventfd handler, qemu decides on
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what action to take. In this implementation, guest is brought down to
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contain the error.
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The kernel patches for the above functionality has been already accepted.
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This is a refresh of the QEMU patch which was reviewed earlier.
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http://marc.info/?l=linux-kernel&m=136281557608087&w=2
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This patch has the same contents and has been built after refreshing
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to latest upstream and after the linux headers have been updated in qemu.
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	- Create eventfd per vfio device assigned to a guest and register an
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          event handler
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	- This fd is passed to the vfio_pci driver through the SET_IRQ ioctl
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	- When the device encounters an error, the eventfd is signalled
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          and the qemu eventfd handler gets invoked.
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	- In the handler decide what action to take. Current action taken
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          is to stop the guest.
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Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
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Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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(cherry picked from commit 7b4b0e9eda51902b53bc1a2318df53cdb8b72eed)
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diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
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index 693a9ff..f8fef8c 100644
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--- a/hw/misc/vfio.c
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+++ b/hw/misc/vfio.c
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@@ -158,6 +158,7 @@ typedef struct VFIODevice {
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     PCIHostDeviceAddress host;
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     QLIST_ENTRY(VFIODevice) next;
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     struct VFIOGroup *group;
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+    EventNotifier err_notifier;
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     uint32_t features;
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 #define VFIO_FEATURE_ENABLE_VGA_BIT 0
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 #define VFIO_FEATURE_ENABLE_VGA (1 << VFIO_FEATURE_ENABLE_VGA_BIT)
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@@ -165,6 +166,7 @@ typedef struct VFIODevice {
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     uint8_t pm_cap;
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     bool reset_works;
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     bool has_vga;
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+    bool pci_aer;
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 } VFIODevice;
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 typedef struct VFIOGroup {
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@@ -2776,6 +2778,7 @@ static int vfio_get_device(VFIOGroup *group, const char *name, VFIODevice *vdev)
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 {
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     struct vfio_device_info dev_info = { .argsz = sizeof(dev_info) };
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     struct vfio_region_info reg_info = { .argsz = sizeof(reg_info) };
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+    struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info) };
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     int ret, i;
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     ret = ioctl(group->fd, VFIO_GROUP_GET_DEVICE_FD, name);
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@@ -2919,6 +2922,19 @@ static int vfio_get_device(VFIOGroup *group, const char *name, VFIODevice *vdev)
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         vdev->has_vga = true;
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     }
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+    irq_info.index = VFIO_PCI_ERR_IRQ_INDEX;
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+
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+    ret = ioctl(vdev->fd, VFIO_DEVICE_GET_IRQ_INFO, &irq_info);
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+    if (ret) {
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+        /* This can fail for an old kernel or legacy PCI dev */
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+        DPRINTF("VFIO_DEVICE_GET_IRQ_INFO failure ret=%d\n", ret);
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+        ret = 0;
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+    } else if (irq_info.count == 1) {
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+        vdev->pci_aer = true;
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+    } else {
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+        error_report("vfio: Warning: "
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+                     "Could not enable error recovery for the device\n");
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+    }
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 error:
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     if (ret) {
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@@ -2941,6 +2957,113 @@ static void vfio_put_device(VFIODevice *vdev)
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     }
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 }
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+static void vfio_err_notifier_handler(void *opaque)
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+{
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+    VFIODevice *vdev = opaque;
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+
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+    if (!event_notifier_test_and_clear(&vdev->err_notifier)) {
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+        return;
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+    }
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+
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+    /*
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+     * TBD. Retrieve the error details and decide what action
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+     * needs to be taken. One of the actions could be to pass
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+     * the error to the guest and have the guest driver recover
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+     * from the error. This requires that PCIe capabilities be
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+     * exposed to the guest. For now, we just terminate the
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+     * guest to contain the error.
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+     */
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+
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+    error_report("%s (%04x:%02x:%02x.%x)"
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+        "Unrecoverable error detected...\n"
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+        "Please collect any data possible and then kill the guest",
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+        __func__, vdev->host.domain, vdev->host.bus,
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+        vdev->host.slot, vdev->host.function);
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+
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+    vm_stop(RUN_STATE_IO_ERROR);
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+}
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+
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+/*
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+ * Registers error notifier for devices supporting error recovery.
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+ * If we encounter a failure in this function, we report an error
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+ * and continue after disabling error recovery support for the
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+ * device.
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+ */
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+static void vfio_register_err_notifier(VFIODevice *vdev)
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+{
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+    int ret;
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+    int argsz;
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+    struct vfio_irq_set *irq_set;
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+    int32_t *pfd;
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+
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+    if (!vdev->pci_aer) {
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+        return;
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+    }
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+
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+    if (event_notifier_init(&vdev->err_notifier, 0)) {
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+        error_report("vfio: Warning: "
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+                     "Unable to init event notifier for error detection\n");
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+        vdev->pci_aer = false;
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+        return;
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+    }
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+
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+    argsz = sizeof(*irq_set) + sizeof(*pfd);
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+
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+    irq_set = g_malloc0(argsz);
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+    irq_set->argsz = argsz;
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+    irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
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+                     VFIO_IRQ_SET_ACTION_TRIGGER;
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+    irq_set->index = VFIO_PCI_ERR_IRQ_INDEX;
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+    irq_set->start = 0;
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+    irq_set->count = 1;
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+    pfd = (int32_t *)&irq_set->data;
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+
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+    *pfd = event_notifier_get_fd(&vdev->err_notifier);
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+    qemu_set_fd_handler(*pfd, vfio_err_notifier_handler, NULL, vdev);
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+
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+    ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
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+    if (ret) {
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+        error_report("vfio: Failed to set up error notification\n");
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+        qemu_set_fd_handler(*pfd, NULL, NULL, vdev);
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+        event_notifier_cleanup(&vdev->err_notifier);
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+        vdev->pci_aer = false;
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+    }
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+    g_free(irq_set);
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+}
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+
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+static void vfio_unregister_err_notifier(VFIODevice *vdev)
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+{
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+    int argsz;
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+    struct vfio_irq_set *irq_set;
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+    int32_t *pfd;
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+    int ret;
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+
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+    if (!vdev->pci_aer) {
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+        return;
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+    }
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+
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+    argsz = sizeof(*irq_set) + sizeof(*pfd);
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+
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+    irq_set = g_malloc0(argsz);
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+    irq_set->argsz = argsz;
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+    irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
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+                     VFIO_IRQ_SET_ACTION_TRIGGER;
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+    irq_set->index = VFIO_PCI_ERR_IRQ_INDEX;
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+    irq_set->start = 0;
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+    irq_set->count = 1;
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+    pfd = (int32_t *)&irq_set->data;
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+    *pfd = -1;
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+
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+    ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
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+    if (ret) {
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+        error_report("vfio: Failed to de-assign error fd: %d\n", ret);
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+    }
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+    g_free(irq_set);
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+    qemu_set_fd_handler(event_notifier_get_fd(&vdev->err_notifier),
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+                        NULL, NULL, vdev);
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+    event_notifier_cleanup(&vdev->err_notifier);
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+}
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+
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 static int vfio_initfn(PCIDevice *pdev)
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 {
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     VFIODevice *pvdev, *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
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@@ -3073,6 +3196,7 @@ static int vfio_initfn(PCIDevice *pdev)
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     }
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     add_boot_device_path(vdev->bootindex, &pdev->qdev, NULL);
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+    vfio_register_err_notifier(vdev);
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     return 0;
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@@ -3092,6 +3216,7 @@ static void vfio_exitfn(PCIDevice *pdev)
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     VFIODevice *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
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     VFIOGroup *group = vdev->group;
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+    vfio_unregister_err_notifier(vdev);
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     pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
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     vfio_disable_interrupts(vdev);
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     if (vdev->intx.mmap_timer) {