[Qemu-devel] [PATCH 08/10] vfio: introduce last reset sequence id

[Cao jin]

From: Chen Fan <chen.fan.f...@cn.fujitsu.com>

avoid multi-reset host bus, we introduce sequence id to specify which
bus is resetting. and if one of the dependent devices has done a reset.
the others should skip.

Signed-off-by: Chen Fan <chen.fan.f...@cn.fujitsu.com>
---
 hw/vfio/pci.c | 14 ++++++++++++++
 hw/vfio/pci.h |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index b900f70..5b885e7 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -1951,6 +1951,8 @@ static int vfio_check_host_bus_reset(VFIOPCIDevice *vdev)
     /* List all affected devices by bus reset */
     devices = &info->devices[0];
 
+    vdev->single_depend_dev = (info->count == 1);
+
     /* Verify that we have all the groups required */
     for (i = 0; i < info->count; i++) {
         PCIHostDeviceAddress host;
@@ -2283,6 +2285,7 @@ static int vfio_pci_hot_reset(VFIOPCIDevice *vdev, bool 
single)
 
     vfio_pci_pre_reset(vdev);
     vdev->vbasedev.needs_reset = false;
+    vdev->last_bus_reset_seqid = vdev->pdev.bus->reset_seqid;
 
     ret = vfio_get_hot_reset_info(vdev, &info);
     if (ret) {
@@ -2344,6 +2347,7 @@ static int vfio_pci_hot_reset(VFIOPCIDevice *vdev, bool 
single)
                 }
                 vfio_pci_pre_reset(tmp);
                 tmp->vbasedev.needs_reset = false;
+                tmp->last_bus_reset_seqid = vdev->pdev.bus->reset_seqid;
                 multi = true;
                 break;
             }
@@ -3040,6 +3044,16 @@ static void vfio_pci_reset(DeviceState *dev)
 
     trace_vfio_pci_reset(vdev->vbasedev.name);
 
+    /* if need to do a hot reset */
+    if (pdev->bus->bus_in_reset) {
+        if (vdev->last_bus_reset_seqid == pdev->bus->reset_seqid) {
+            return;
+        } else if ((vdev->features & VFIO_FEATURE_ENABLE_AER)) {
+            vfio_pci_hot_reset(vdev, vdev->single_depend_dev);
+            return;
+        }
+    }
+
     vfio_pci_pre_reset(vdev);
 
     if (vdev->resetfn && !vdev->resetfn(vdev)) {
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index bf9e93c..684931d 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -144,6 +144,9 @@ typedef struct VFIOPCIDevice {
     bool no_kvm_msi;
     bool no_kvm_msix;
 
+    bool single_depend_dev;
+    uint32_t last_bus_reset_seqid;
+
     NotifierWithReturn hotplug_notifier;
 } VFIOPCIDevice;
 
-- 
1.9.3