[Qemu-devel] [PATCH 2/2] QEMU-AER: Qemu changes to support AER for VFIO-PCI devices

[Pandarathil, Vijaymohan R]

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

        - This fd is passed to the vfio_pci driver through a new ioctl

        - When the device encounters an error, the eventfd is signaled
          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 <address@hidden>
---
 hw/vfio_pci.c              | 56 ++++++++++++++++++++++++++++++++++++++++++++++
 linux-headers/linux/vfio.h |  9 ++++++++
 2 files changed, 65 insertions(+)

diff --git a/hw/vfio_pci.c b/hw/vfio_pci.c
index 28c8303..9c3c28b 100644
--- a/hw/vfio_pci.c
+++ b/hw/vfio_pci.c
@@ -38,6 +38,7 @@
 #include "qemu/error-report.h"
 #include "qemu/queue.h"
 #include "qemu/range.h"
+#include "sysemu/sysemu.h"
 
 /* #define DEBUG_VFIO */
 #ifdef DEBUG_VFIO
@@ -130,6 +131,8 @@ typedef struct VFIODevice {
     QLIST_ENTRY(VFIODevice) next;
     struct VFIOGroup *group;
     bool reset_works;
+    EventNotifier errfd;
+    __u32 dev_info_flags;
 } VFIODevice;
 
 typedef struct VFIOGroup {
@@ -1805,6 +1808,8 @@ static int vfio_get_device(VFIOGroup *group, const char 
*name, VFIODevice *vdev)
     DPRINTF("Device %s flags: %u, regions: %u, irgs: %u\n", name,
             dev_info.flags, dev_info.num_regions, dev_info.num_irqs);
 
+    vdev->dev_info_flags = dev_info.flags;
+
     if (!(dev_info.flags & VFIO_DEVICE_FLAGS_PCI)) {
         error_report("vfio: Um, this isn't a PCI device\n");
         goto error;
@@ -1900,6 +1905,55 @@ static void vfio_put_device(VFIODevice *vdev)
     }
 }
 
+static void vfio_errfd_handler(void *opaque)
+{
+    VFIODevice *vdev = opaque;
+
+    if (!event_notifier_test_and_clear(&vdev->errfd)) {
+        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
+     * 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);
+
+    qemu_system_shutdown_request();
+    return;
+}
+
+static void vfio_register_errfd(VFIODevice *vdev)
+{
+    int32_t pfd;
+    int ret;
+
+    if (!(vdev->dev_info_flags & VFIO_DEVICE_FLAGS_AER_NOTIFY)) {
+        error_report("vfio: Warning: Error notification not supported for the 
device\n");
+        return;
+    }
+    if (event_notifier_init(&vdev->errfd, 0)) {
+        error_report("vfio: Warning: Unable to init event notifier for error 
detection\n");
+        return;
+    }
+    pfd = event_notifier_get_fd(&vdev->errfd);
+    qemu_set_fd_handler(pfd, vfio_errfd_handler, NULL, vdev);
+
+    ret = ioctl(vdev->fd, VFIO_DEVICE_SET_ERRFD, pfd);
+    if (ret) {
+        error_report("vfio: Warning: Failed to setup error fd: %d\n", ret);
+        qemu_set_fd_handler(pfd, NULL, NULL, vdev);
+        event_notifier_cleanup(&vdev->errfd);
+    }
+    return;
+}
 static int vfio_initfn(PCIDevice *pdev)
 {
     VFIODevice *pvdev, *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
@@ -2010,6 +2064,8 @@ static int vfio_initfn(PCIDevice *pdev)
         }
     }
 
+    vfio_register_errfd(vdev);
+
     return 0;
 
 out_teardown:
diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
index 4758d1b..0ca4eeb 100644
--- a/linux-headers/linux/vfio.h
+++ b/linux-headers/linux/vfio.h
@@ -147,6 +147,7 @@ struct vfio_device_info {
        __u32   flags;
 #define VFIO_DEVICE_FLAGS_RESET        (1 << 0)        /* Device supports 
reset */
 #define VFIO_DEVICE_FLAGS_PCI  (1 << 1)        /* vfio-pci device */
+#define VFIO_DEVICE_FLAGS_AER_NOTIFY (1 << 2)   /* Supports aer notification */
        __u32   num_regions;    /* Max region index + 1 */
        __u32   num_irqs;       /* Max IRQ index + 1 */
 };
@@ -288,6 +289,14 @@ struct vfio_irq_set {
  */
 #define VFIO_DEVICE_RESET              _IO(VFIO_TYPE, VFIO_BASE + 11)
 
+/**
+ * VFIO_DEVICE_SET_ERRFD - _IO(VFIO_TYPE, VFIO_BASE + 12)
+ *
+ * Pass the eventfd to the vfio-pci driver for signalling any device
+ * error notifications
+ */
+#define VFIO_DEVICE_SET_ERRFD           _IO(VFIO_TYPE, VFIO_BASE + 12)
+
 /*
  * The VFIO-PCI bus driver makes use of the following fixed region and
  * IRQ index mapping.  Unimplemented regions return a size of zero.
-- 
1.7.11.3