[PATCH] hw/pci/pcie: Forbid hot-plug via QMP if it's disabled on the slot

[Julia Suvorova <jusual@redhat.com>]

Raise an error when trying to hot-plug/unplug a device through QMP to a device
with disabled hot-plug capability. This makes the device behaviour more
consistent and provides an explanation of the failure in the case of
asynchronous unplug.

Signed-off-by: Julia Suvorova <jusual@redhat.com>
---
 hw/pci/pcie.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 0eb3a2a5d2..e9798caa8a 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -415,6 +415,7 @@ void pcie_cap_slot_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
 {
     PCIDevice *hotplug_pdev = PCI_DEVICE(hotplug_dev);
     uint8_t *exp_cap = hotplug_pdev->config + hotplug_pdev->exp.exp_cap;
+    uint32_t sltcap = pci_get_word(exp_cap + PCI_EXP_SLTCAP);
     PCIDevice *pci_dev = PCI_DEVICE(dev);
 
     /* Don't send event when device is enabled during qemu machine creation:
@@ -430,6 +431,13 @@ void pcie_cap_slot_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
         return;
     }
 
+    /* Hot-plug is disabled on the slot */
+    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
+        error_setg(errp, "Device '%s' does not support hot-plug",
+                         DEVICE(hotplug_dev)->id);
+        return;
+    }
+
     /* To enable multifunction hot-plug, we just ensure the function
      * 0 added last. When function 0 is added, we set the sltsta and
      * inform OS via event notification.
@@ -464,14 +472,24 @@ static void pcie_unplug_device(PCIBus *bus, PCIDevice *dev, void *opaque)
     object_unparent(OBJECT(dev));
 }
 
-void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
+void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_handler,
                                      DeviceState *dev, Error **errp)
 {
     Error *local_err = NULL;
     PCIDevice *pci_dev = PCI_DEVICE(dev);
     PCIBus *bus = pci_get_bus(pci_dev);
+    PCIDevice *hotplug_dev = PCI_DEVICE(hotplug_handler);
+    uint8_t *exp_cap = hotplug_dev->config + hotplug_dev->exp.exp_cap;
+    uint32_t sltcap = pci_get_word(exp_cap + PCI_EXP_SLTCAP);
+
+    /* Hot-unplug is disabled on the slot */
+    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
+        error_setg(errp, "Device '%s' does not support hot-unplug",
+                         DEVICE(hotplug_dev)->id);
+        return;
+    }
 
-    pcie_cap_slot_plug_common(PCI_DEVICE(hotplug_dev), dev, &local_err);
+    pcie_cap_slot_plug_common(hotplug_dev, dev, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -490,7 +508,7 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
         return;
     }
 
-    pcie_cap_slot_push_attention_button(PCI_DEVICE(hotplug_dev));
+    pcie_cap_slot_push_attention_button(hotplug_dev);
 }
 
 /* pci express slot for pci express root/downstream port
-- 
2.24.1