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Subject[PATCH v3 3/3] QEMU-AER: Qemu changes to support AER for VFIO-PCI devices
Date

- Create eventfd per vfio device assigned to a guest and register an
event handler

- This fd is passed to the vfio_pci driver through the SET_IRQ ioctl

- When the device encounters an error, the eventfd is signalled
and the qemu eventfd handler gets invoked.

- In the handler decide what action to take. Current action taken
is to terminate the guest.

Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
---
hw/vfio_pci.c | 105 +++++++++++++++++++++++++++++++++++++++++++++
linux-headers/linux/vfio.h | 1 +
2 files changed, 106 insertions(+)

diff --git a/hw/vfio_pci.c b/hw/vfio_pci.c
index c51ae67..4e2f768 100644
--- a/hw/vfio_pci.c
+++ b/hw/vfio_pci.c
@@ -130,6 +130,8 @@ typedef struct VFIODevice {
QLIST_ENTRY(VFIODevice) next;
struct VFIOGroup *group;
bool reset_works;
+ EventNotifier err_notifier;
+ bool pci_aer;
} VFIODevice;

typedef struct VFIOGroup {
@@ -1922,6 +1924,106 @@ static void vfio_put_device(VFIODevice *vdev)
}
}

+static void vfio_err_notifier_handler(void *opaque)
+{
+ VFIODevice *vdev = opaque;
+
+ if (!event_notifier_test_and_clear(&vdev->err_notifier)) {
+ return;
+ }
+
+ /*
+ * TBD. Retrieve the error details and decide what action
+ * needs to be taken. One of the actions could be to pass
+ * the error to the guest and have the guest driver recover
+ * from the error. This requires that PCIe capabilities be
+ * exposed to the guest. At present, we just terminate the
+ * guest to contain the error.
+ */
+
+ error_report("%s (%04x:%02x:%02x.%x)"
+ "Unrecoverable error detected... Terminating guest\n",
+ __func__, vdev->host.domain, vdev->host.bus,
+ vdev->host.slot, vdev->host.function);
+
+ hw_error("(%04x:%02x:%02x.%x) Unrecoverable device error\n",
+ vdev->host.domain, vdev->host.bus,
+ vdev->host.slot, vdev->host.function);
+
+ return;
+}
+
+static void vfio_register_err_notifier(VFIODevice *vdev)
+{
+ int ret;
+ int argsz;
+ struct vfio_irq_set *irq_set;
+ int32_t *pfd;
+
+ if (event_notifier_init(&vdev->err_notifier, 0)) {
+ error_report("vfio: Warning: Unable to init event notifier for error detection\n");
+ return;
+ }
+
+ argsz = sizeof(*irq_set) + sizeof(*pfd);
+
+ irq_set = g_malloc0(argsz);
+ irq_set->argsz = argsz;
+ irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
+ VFIO_IRQ_SET_ACTION_TRIGGER;
+ irq_set->index = VFIO_PCI_ERR_IRQ_INDEX;
+ irq_set->start = 0;
+ irq_set->count = 1;
+ pfd = (int32_t *)&irq_set->data;
+
+ *pfd = event_notifier_get_fd(&vdev->err_notifier);
+ qemu_set_fd_handler(*pfd, vfio_err_notifier_handler, NULL, vdev);
+
+ ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
+ if (ret) {
+ DPRINTF("vfio: Error notification not supported for the device\n");
+ qemu_set_fd_handler(*pfd, NULL, NULL, vdev);
+ event_notifier_cleanup(&vdev->err_notifier);
+ g_free(irq_set);
+ return;
+ }
+ g_free(irq_set);
+ vdev->pci_aer = 1;
+ return;
+}
+static void vfio_unregister_err_notifier(VFIODevice *vdev)
+{
+ int argsz;
+ struct vfio_irq_set *irq_set;
+ int32_t *pfd;
+ int ret;
+
+ if (!vdev->pci_aer) {
+ return;
+ }
+
+ argsz = sizeof(*irq_set) + sizeof(*pfd);
+
+ irq_set = g_malloc0(argsz);
+ irq_set->argsz = argsz;
+ irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
+ VFIO_IRQ_SET_ACTION_TRIGGER;
+ irq_set->index = VFIO_PCI_ERR_IRQ_INDEX;
+ irq_set->start = 0;
+ irq_set->count = 1;
+ pfd = (int32_t *)&irq_set->data;
+ *pfd = -1;
+
+ ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
+ if (ret) {
+ DPRINTF("vfio: Failed to de-assign error fd: %d\n", ret);
+ }
+ g_free(irq_set);
+ qemu_set_fd_handler(event_notifier_get_fd(&vdev->err_notifier),
+ NULL, NULL, vdev);
+ event_notifier_cleanup(&vdev->err_notifier);
+ return;
+}
static int vfio_initfn(PCIDevice *pdev)
{
VFIODevice *pvdev, *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
@@ -2032,6 +2134,8 @@ static int vfio_initfn(PCIDevice *pdev)
}
}

+ vfio_register_err_notifier(vdev);
+
return 0;

out_teardown:
@@ -2049,6 +2153,7 @@ static void vfio_exitfn(PCIDevice *pdev)
VFIODevice *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
VFIOGroup *group = vdev->group;

+ vfio_unregister_err_notifier(vdev);
pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
vfio_disable_interrupts(vdev);
if (vdev->intx.mmap_timer) {
diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
index f787b72..6b20849 100644
--- a/linux-headers/linux/vfio.h
+++ b/linux-headers/linux/vfio.h
@@ -310,6 +310,7 @@ enum {
VFIO_PCI_INTX_IRQ_INDEX,
VFIO_PCI_MSI_IRQ_INDEX,
VFIO_PCI_MSIX_IRQ_INDEX,
+ VFIO_PCI_ERR_IRQ_INDEX,
VFIO_PCI_NUM_IRQS
};

--
1.7.11.3


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