[Qemu-devel] [Resend RFC PATCH 1/4] VFIO: Set eventfd for IOMMU fault event via new vfio cmd

[Lan Tianyu]

This patch is to assign an event fd to VFIO IOMMU type1 driver
in order to get notification when IOMMU driver reports fault event.

Signed-off-by: Lan Tianyu <tianyu....@intel.com>
---
 hw/vfio/common.c              | 37 +++++++++++++++++++++++++++++++++++++
 include/hw/vfio/vfio-common.h |  3 +++
 linux-headers/linux/vfio.h    | 13 +++++++++++++
 3 files changed, 53 insertions(+)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 6b33b9f..628b424 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -33,6 +33,7 @@
 #include "qemu/error-report.h"
 #include "qemu/range.h"
 #include "sysemu/kvm.h"
+#include "sysemu/sysemu.h"
 #include "trace.h"
 #include "qapi/error.h"
 
@@ -294,6 +295,34 @@ static bool 
vfio_listener_skipped_section(MemoryRegionSection *section)
            section->offset_within_address_space & (1ULL << 63);
 }
 
+static void vfio_iommu_fault(void *opaque)
+{
+}
+
+static int vfio_set_iommu_fault_notifier(struct VFIOContainer *container)
+{
+    struct vfio_iommu_type1_set_fault_eventfd eventfd;
+    int ret;
+
+    ret = event_notifier_init(&container->fault_notifier, 0);
+    if (ret < 0) {
+        error_report("vfio: Failed to init notifier for IOMMU fault event");
+        return ret;
+    }
+
+    eventfd.fd = event_notifier_get_fd(&container->fault_notifier);
+    eventfd.argsz = sizeof(eventfd);
+
+    ret = ioctl(container->fd, VFIO_IOMMU_SET_FAULT_EVENTFD, &eventfd);
+    if (ret < 0) {
+        error_report("vfio: Failed to set notifier for IOMMU fault event");
+        return ret;
+    }
+
+    qemu_set_fd_handler(eventfd.fd, vfio_iommu_fault, NULL, container);
+    return 0;
+}
+
 /* Called with rcu_read_lock held.  */
 static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, void **vaddr,
                            bool *read_only)
@@ -1103,6 +1132,14 @@ static int vfio_connect_container(VFIOGroup *group, 
AddressSpace *as,
         goto listener_release_exit;
     }
 
+    if (memory_region_is_iommu(container->space->as->root)) {
+        if (vfio_set_iommu_fault_notifier(container)) {
+            error_setg_errno(errp, -ret,
+                "Fail to set IOMMU fault notifier");
+            goto listener_release_exit;
+        }
+    }
+
     container->initialized = true;
 
     QLIST_INIT(&container->group_list);
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index c582de1..1b594c6 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -26,6 +26,7 @@
 #include "exec/memory.h"
 #include "qemu/queue.h"
 #include "qemu/notify.h"
+#include "qemu/event_notifier.h"
 #ifdef CONFIG_LINUX
 #include <linux/vfio.h>
 #endif
@@ -81,6 +82,8 @@ typedef struct VFIOContainer {
     unsigned iommu_type;
     int error;
     bool initialized;
+    EventNotifier fault_notifier;
+
     /*
      * This assumes the host IOMMU can support only a single
      * contiguous IOVA window.  We may need to generalize that in
diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
index 759b850..ca890ee 100644
--- a/linux-headers/linux/vfio.h
+++ b/linux-headers/linux/vfio.h
@@ -537,6 +537,19 @@ struct vfio_iommu_type1_dma_unmap {
 #define VFIO_IOMMU_ENABLE      _IO(VFIO_TYPE, VFIO_BASE + 15)
 #define VFIO_IOMMU_DISABLE     _IO(VFIO_TYPE, VFIO_BASE + 16)
 
+/*
+ * VFIO_IOMMU_SET_FAULT_EVENT_FD       _IO(VFIO_TYPE, VFIO_BASE + 17)
+ * 
+ * Receive eventfd from userspace to notify fault event from IOMMU.
+ */
+struct vfio_iommu_type1_set_fault_eventfd {
+       __u32   argsz;
+       __u32   flags;
+       __u32   fd;
+};
+
+#define VFIO_IOMMU_SET_FAULT_EVENTFD   _IO(VFIO_TYPE, VFIO_BASE + 17)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
1.8.3.1