[Qemu-devel] [RFC v8.1 06/13] vfio: add check host bus reset is support or not

[Chen Fan]

we introduce a has_bus_reset capability to sign the vfio
devices if support host bus reset.

Signed-off-by: Chen Fan <address@hidden>
---
 hw/vfio/pci.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index f4e7855..5934fd7 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -33,6 +33,7 @@
 #include "hw/pci/msix.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_bridge.h"
+#include "hw/pci/pci_bus.h"
 #include "qemu-common.h"
 #include "qemu/error-report.h"
 #include "qemu/event_notifier.h"
@@ -170,6 +171,7 @@ typedef struct VFIOPCIDevice {
     bool req_enabled;
     bool has_flr;
     bool has_pm_reset;
+    bool has_bus_reset;
     bool rom_read_failed;
 } VFIOPCIDevice;
 
@@ -203,6 +205,7 @@ static uint32_t vfio_pci_read_config(PCIDevice *pdev, 
uint32_t addr, int len);
 static void vfio_pci_write_config(PCIDevice *pdev, uint32_t addr,
                                   uint32_t val, int len);
 static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled);
+static void vfio_check_host_bus_reset(VFIOPCIDevice *vdev);
 
 /*
  * Disabling BAR mmaping can be slow, but toggling it around INTx can
@@ -2853,6 +2856,20 @@ static int vfio_setup_aer(VFIOPCIDevice *vdev, int pos, 
uint16_t size)
         dev_iter = pci_bridge_get_device(dev_iter->bus);
     }
 
+    /*
+     * Don't check bus reset capability when device is enabled during
+     * qemu machine creation, which is done by machine init function.
+     */
+    if (DEVICE(vdev)->hotplugged) {
+        vfio_check_host_bus_reset(vdev);
+        if (!vdev->has_bus_reset) {
+            error_report("vfio: Cannot enable AER for device %s, "
+                         "which is not support host bus reset.",
+                         vdev->vbasedev.name);
+            goto error;
+        }
+    }
+
     errcap = vfio_pci_read_config(pdev, pdev->exp.aer_cap + PCI_ERR_CAP, 4);
     /*
      * The ability to record multiple headers is depending on
@@ -3678,6 +3695,112 @@ static void vfio_setup_resetfn(VFIOPCIDevice *vdev)
     }
 }
 
+struct VfioDeviceFind {
+    PCIBus *pbus;
+    PCIDevice *pdev;
+    bool found;
+};
+
+static void find_devices(PCIBus *bus, void *opaque)
+{
+    struct VfioDeviceFind *find = opaque;
+    int i;
+
+    if (find->found == true) {
+        return;
+    }
+
+    for (i = 0; i < ARRAY_SIZE(bus->devices); i++) {
+        if (!bus->devices[i]) {
+            continue;
+        }
+
+        if (bus->devices[i] == find->pdev) {
+            find->pbus = bus;
+            find->found = true;
+            break;
+        }
+    }
+}
+
+static void vfio_check_host_bus_reset(VFIOPCIDevice *vdev)
+{
+    PCIBus *bus = vdev->pdev.bus;
+    struct vfio_pci_hot_reset_info *info = NULL;
+    struct vfio_pci_dependent_device *devices;
+    VFIOGroup *group;
+    int ret, i;
+    bool has_bus_reset = false;
+
+    ret = vfio_get_hot_reset_info(vdev, &info);
+    if (ret < 0) {
+        goto out;
+    }
+
+    /* List all affected devices by bus reset */
+    devices = &info->devices[0];
+
+    /* Verify that we have all the groups required */
+    for (i = 0; i < info->count; i++) {
+        PCIHostDeviceAddress host;
+        VFIOPCIDevice *tmp;
+        VFIODevice *vbasedev_iter;
+
+        host.domain = devices[i].segment;
+        host.bus = devices[i].bus;
+        host.slot = PCI_SLOT(devices[i].devfn);
+        host.function = PCI_FUNC(devices[i].devfn);
+
+        /* Skip the current device */
+        if (vfio_pci_host_match(&host, &vdev->host)) {
+            continue;
+        }
+
+        /* Ensure we own the group of the affected device */
+        QLIST_FOREACH(group, &vfio_group_list, next) {
+            if (group->groupid == devices[i].group_id) {
+                break;
+            }
+        }
+
+        if (!group) {
+            goto out;
+        }
+
+        /* Ensure affected devices for reset under the same bus */
+        QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
+            if (vbasedev_iter->type != VFIO_DEVICE_TYPE_PCI) {
+                continue;
+            }
+            tmp = container_of(vbasedev_iter, VFIOPCIDevice, vbasedev);
+            if (vfio_pci_host_match(&host, &tmp->host)) {
+                struct VfioDeviceFind find = { .pdev = &tmp->pdev, .found = 
false };
+
+                pci_for_each_bus(bus, find_devices, &find);
+                if (!find.found) {
+                    goto out;
+                }
+                /*
+                 * When the check device is hotplugged to a higher bus again,
+                 * which would influence the affected device which enable aer
+                 * below the bus.
+                 */
+                if (tmp->features & VFIO_FEATURE_ENABLE_AER &&
+                    find.pbus != bus) {
+                    goto out;
+                }
+                break;
+            }
+        }
+    }
+
+    has_bus_reset = true;
+
+out:
+    vdev->has_bus_reset = has_bus_reset;
+    g_free(info);
+}
+
 static int vfio_initfn(PCIDevice *pdev)
 {
     VFIOPCIDevice *vdev = DO_UPCAST(VFIOPCIDevice, pdev, pdev);
-- 
1.9.3