[PATCH 68/77] virtio-pci: Changed vdev to proxy for VirtIO PCI BAR callbacks.

[Michael Roth]

From: Andrew Melnychenko <andrew@daynix.com>

There is an issue when callback may be called with invalid vdev.
It happens on unplug when vdev already deleted and VirtIOPciProxy is not.
So now, callbacks accept proxy device, and vdev retrieved from it.
Technically memio callbacks should be removed during the flatview update,
but memoryregions remain til PCI device(and it's address space) completely 
deleted.
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1716352

Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
Message-Id: <20200706112123.971087-1-andrew@daynix.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit ccec7e9603f446fe75c6c563ba335c00cfda6a06)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hw/virtio/virtio-pci.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 2ca266e1cb..ef11c66a21 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1317,11 +1317,12 @@ static uint64_t virtio_pci_notify_read(void *opaque, 
hwaddr addr,
 static void virtio_pci_notify_write(void *opaque, hwaddr addr,
                                     uint64_t val, unsigned size)
 {
-    VirtIODevice *vdev = opaque;
-    VirtIOPCIProxy *proxy = VIRTIO_PCI(DEVICE(vdev)->parent_bus->parent);
+    VirtIOPCIProxy *proxy = opaque;
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+
     unsigned queue = addr / virtio_pci_queue_mem_mult(proxy);
 
-    if (queue < VIRTIO_QUEUE_MAX) {
+    if (vdev != NULL && queue < VIRTIO_QUEUE_MAX) {
         virtio_queue_notify(vdev, queue);
     }
 }
@@ -1329,10 +1330,12 @@ static void virtio_pci_notify_write(void *opaque, 
hwaddr addr,
 static void virtio_pci_notify_write_pio(void *opaque, hwaddr addr,
                                         uint64_t val, unsigned size)
 {
-    VirtIODevice *vdev = opaque;
+    VirtIOPCIProxy *proxy = opaque;
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+
     unsigned queue = val;
 
-    if (queue < VIRTIO_QUEUE_MAX) {
+    if (vdev != NULL && queue < VIRTIO_QUEUE_MAX) {
         virtio_queue_notify(vdev, queue);
     }
 }
@@ -1356,9 +1359,14 @@ static void virtio_pci_isr_write(void *opaque, hwaddr 
addr,
 static uint64_t virtio_pci_device_read(void *opaque, hwaddr addr,
                                        unsigned size)
 {
-    VirtIODevice *vdev = opaque;
+    VirtIOPCIProxy *proxy = opaque;
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
     uint64_t val = 0;
 
+    if (vdev == NULL) {
+        return val;
+    }
+
     switch (size) {
     case 1:
         val = virtio_config_modern_readb(vdev, addr);
@@ -1376,7 +1384,13 @@ static uint64_t virtio_pci_device_read(void *opaque, 
hwaddr addr,
 static void virtio_pci_device_write(void *opaque, hwaddr addr,
                                     uint64_t val, unsigned size)
 {
-    VirtIODevice *vdev = opaque;
+    VirtIOPCIProxy *proxy = opaque;
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+
+    if (vdev == NULL) {
+        return;
+    }
+
     switch (size) {
     case 1:
         virtio_config_modern_writeb(vdev, addr, val);
@@ -1453,19 +1467,19 @@ static void 
virtio_pci_modern_regions_init(VirtIOPCIProxy *proxy)
 
     memory_region_init_io(&proxy->device.mr, OBJECT(proxy),
                           &device_ops,
-                          virtio_bus_get_device(&proxy->bus),
+                          proxy,
                           "virtio-pci-device",
                           proxy->device.size);
 
     memory_region_init_io(&proxy->notify.mr, OBJECT(proxy),
                           &notify_ops,
-                          virtio_bus_get_device(&proxy->bus),
+                          proxy,
                           "virtio-pci-notify",
                           proxy->notify.size);
 
     memory_region_init_io(&proxy->notify_pio.mr, OBJECT(proxy),
                           &notify_pio_ops,
-                          virtio_bus_get_device(&proxy->bus),
+                          proxy,
                           "virtio-pci-notify-pio",
                           proxy->notify_pio.size);
 }
-- 
2.17.1