From: Viktor Prutyanov <viktor@daynix.com>

According to PCIe Address Translation Services specification 5.1.3.,
ATS Control Register has Enable bit to enable/disable ATS. Guest may
enable/disable PCI ATS and, accordingly, Device-TLB for the VirtIO PCI
device. So, raise/lower a flag and call a trigger function to pass this
event to a device implementation.

Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Message-Id: <20230512135122.70403-2-viktor@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/hw/virtio/virtio.h |  2 ++
 hw/virtio/virtio-pci.c     | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index f6b38f7e9c..af86ed7249 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -155,6 +155,7 @@ struct VirtIODevice
     QLIST_HEAD(, VirtQueue) *vector_queues;
     QTAILQ_ENTRY(VirtIODevice) next;
     EventNotifier config_notifier;
+    bool device_iotlb_enabled;
 };
 
 struct VirtioDeviceClass {
@@ -212,6 +213,7 @@ struct VirtioDeviceClass {
     const VMStateDescription *vmsd;
     bool (*primary_unplug_pending)(void *opaque);
     struct vhost_dev *(*get_vhost)(VirtIODevice *vdev);
+    void (*toggle_device_iotlb)(VirtIODevice *vdev);
 };
 
 void virtio_instance_init_common(Object *proxy_obj, void *data,
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 02fb84a8fa..edbc0daa18 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -716,6 +716,38 @@ virtio_address_space_read(VirtIOPCIProxy *proxy, hwaddr addr,
     }
 }
 
+static void virtio_pci_ats_ctrl_trigger(PCIDevice *pci_dev, bool enable)
+{
+    VirtIOPCIProxy *proxy = VIRTIO_PCI(pci_dev);
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
+
+    vdev->device_iotlb_enabled = enable;
+
+    if (k->toggle_device_iotlb) {
+        k->toggle_device_iotlb(vdev);
+    }
+}
+
+static void pcie_ats_config_write(PCIDevice *dev, uint32_t address,
+                                  uint32_t val, int len)
+{
+    uint32_t off;
+    uint16_t ats_cap = dev->exp.ats_cap;
+
+    if (!ats_cap || address < ats_cap) {
+        return;
+    }
+    off = address - ats_cap;
+    if (off >= PCI_EXT_CAP_ATS_SIZEOF) {
+        return;
+    }
+
+    if (range_covers_byte(off, len, PCI_ATS_CTRL + 1)) {
+        virtio_pci_ats_ctrl_trigger(dev, !!(val & PCI_ATS_CTRL_ENABLE));
+    }
+}
+
 static void virtio_write_config(PCIDevice *pci_dev, uint32_t address,
                                 uint32_t val, int len)
 {
@@ -729,6 +761,10 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address,
         pcie_cap_flr_write_config(pci_dev, address, val, len);
     }
 
+    if (proxy->flags & VIRTIO_PCI_FLAG_ATS) {
+        pcie_ats_config_write(pci_dev, address, val, len);
+    }
+
     if (range_covers_byte(address, len, PCI_COMMAND)) {
         if (!(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER)) {
             virtio_set_disabled(vdev, true);
-- 
MST