pcie_root_port: Add hotplug disabling option

Make hot-plug/hot-unplug on PCIe Root Ports optional to allow libvirt
manage it and restrict unplug for the whole machine. This is going to
prevent user-initiated unplug in guests (Windows mostly).
Hotplug is enabled by default.
Usage:
    -device pcie-root-port,hotplug=off,...

If you want to disable hot-unplug on some downstream ports of one
switch, disable hot-unplug on PCIe Root Port connected to the upstream
port as well as on the selected downstream ports.

Discussion related:
    https://lists.gnu.org/archive/html/qemu-devel/2020-02/msg00530.html

Signed-off-by: Julia Suvorova <jusual@redhat.com>
Message-Id: <20200226174607.205941-1-jusual@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

2 files changed, 8 insertions, 4 deletions

diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 08718188bb..0eb3a2a5d2 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -495,7 +495,7 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
 
 /* pci express slot for pci express root/downstream port
    PCI express capability slot registers */
-void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
+void pcie_cap_slot_init(PCIDevice *dev, PCIESlot *s)
 {
     uint32_t pos = dev->exp.exp_cap;
 
@@ -505,13 +505,16 @@ void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
     pci_long_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCAP,
                                  ~PCI_EXP_SLTCAP_PSN);
     pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
-                               (slot << PCI_EXP_SLTCAP_PSN_SHIFT) |
+                               (s->slot << PCI_EXP_SLTCAP_PSN_SHIFT) |
                                PCI_EXP_SLTCAP_EIP |
-                               PCI_EXP_SLTCAP_HPS |
-                               PCI_EXP_SLTCAP_HPC |
                                PCI_EXP_SLTCAP_PIP |
                                PCI_EXP_SLTCAP_AIP |
                                PCI_EXP_SLTCAP_ABP);
+    if (s->hotplug) {
+        pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
+                                   PCI_EXP_SLTCAP_HPS |
+                                   PCI_EXP_SLTCAP_HPC);
+    }
 
     if (dev->cap_present & QEMU_PCIE_SLTCAP_PCP) {
         pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
diff --git a/hw/pci/pcie_port.c b/hw/pci/pcie_port.c
index f8263cb306..eb563ad435 100644
--- a/hw/pci/pcie_port.c
+++ b/hw/pci/pcie_port.c
@@ -147,6 +147,7 @@ static const TypeInfo pcie_port_type_info = {
 static Property pcie_slot_props[] = {
     DEFINE_PROP_UINT8("chassis", PCIESlot, chassis, 0),
     DEFINE_PROP_UINT16("slot", PCIESlot, slot, 0),
+    DEFINE_PROP_BOOL("hotplug", PCIESlot, hotplug, true),
     DEFINE_PROP_END_OF_LIST()
 };