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>
---
v2:
    * Change error text [Igor, Michael]
    * Move cleanup to a separate patch [Marcel]

 hw/pci/pcie.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 0eb3a2a5d2..6b48d04d2c 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;
     }
 
+    /* Check if hot-plug is disabled on the slot */
+    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
+        error_setg(errp, "Hot-plug failed: unsupported by the port device '%s'",
+                         DEVICE(hotplug_pdev)->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.
@@ -470,6 +478,17 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
     Error *local_err = NULL;
     PCIDevice *pci_dev = PCI_DEVICE(dev);
     PCIBus *bus = pci_get_bus(pci_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);
+
+    /* Check if hot-unplug is disabled on the slot */
+    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
+        error_setg(errp, "Hot-unplug failed: "
+                         "unsupported by the port device '%s'",
+                         DEVICE(hotplug_pdev)->id);
+        return;
+    }
 
     pcie_cap_slot_plug_common(PCI_DEVICE(hotplug_dev), dev, &local_err);
     if (local_err) {
-- 
2.25.3

On 4/27/20 9:24 PM, Julia Suvorova wrote:
> 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>
> ---
> v2:
>      * Change error text [Igor, Michael]
>      * Move cleanup to a separate patch [Marcel]
>
>   hw/pci/pcie.c | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
>
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index 0eb3a2a5d2..6b48d04d2c 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;
>       }
>   
> +    /* Check if hot-plug is disabled on the slot */
> +    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
> +        error_setg(errp, "Hot-plug failed: unsupported by the port device '%s'",
> +                         DEVICE(hotplug_pdev)->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.
> @@ -470,6 +478,17 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
>       Error *local_err = NULL;
>       PCIDevice *pci_dev = PCI_DEVICE(dev);
>       PCIBus *bus = pci_get_bus(pci_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);
> +
> +    /* Check if hot-unplug is disabled on the slot */
> +    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
> +        error_setg(errp, "Hot-unplug failed: "
> +                         "unsupported by the port device '%s'",
> +                         DEVICE(hotplug_pdev)->id);
> +        return;
> +    }
>   
>       pcie_cap_slot_plug_common(PCI_DEVICE(hotplug_dev), dev, &local_err);
>       if (local_err) {

Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>

Thanks,
Marcel