hw/pcie: implement power controller functionality

It is needed by hot-unplug in order to get an indication
from the OS when the device can be physically detached.
Signed-off-by: NMarcel Apfelbaum <marcel.a@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/pci-bridge/ioh3420.c

@@ -180,6 +180,12 @@ PCIESlot *ioh3420_init(PCIBus *bus, int devfn, bool multifunction,
     return PCIE_SLOT(d);
 }
 
+static Property ioh3420_props[] = {
+    DEFINE_PROP_BIT(COMPAT_PROP_PCP, PCIDevice, cap_present,
+                    QEMU_PCIE_SLTCAP_PCP_BITNR, true),
+    DEFINE_PROP_END_OF_LIST()
+};
+
 static const VMStateDescription vmstate_ioh3420 = {
     .name = "ioh-3240-express-root-port",
     .version_id = 1,
@@ -210,6 +216,7 @@ static void ioh3420_class_init(ObjectClass *klass, void *data)
     dc->desc = "Intel IOH device id 3420 PCIE Root Port";
     dc->reset = ioh3420_reset;
     dc->vmsd = &vmstate_ioh3420;
+    dc->props = ioh3420_props;
 }
 
 static const TypeInfo ioh3420_info = {

hw/pci-bridge/xio3130_downstream.c

@@ -147,6 +147,12 @@ PCIESlot *xio3130_downstream_init(PCIBus *bus, int devfn, bool multifunction,
     return PCIE_SLOT(d);
 }
 
+static Property xio3130_downstream_props[] = {
+    DEFINE_PROP_BIT(COMPAT_PROP_PCP, PCIDevice, cap_present,
+                    QEMU_PCIE_SLTCAP_PCP_BITNR, true),
+    DEFINE_PROP_END_OF_LIST()
+};
+
 static const VMStateDescription vmstate_xio3130_downstream = {
     .name = "xio3130-express-downstream-port",
     .version_id = 1,
@@ -177,6 +183,7 @@ static void xio3130_downstream_class_init(ObjectClass *klass, void *data)
     dc->desc = "TI X3130 Downstream Port of PCI Express Switch";
     dc->reset = xio3130_downstream_reset;
     dc->vmsd = &vmstate_xio3130_downstream;
+    dc->props = xio3130_downstream_props;
 }
 
 static const TypeInfo xio3130_downstream_info = {

hw/pci/pcie.c

@@ -294,6 +294,15 @@ void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
                                PCI_EXP_SLTCAP_AIP |
                                PCI_EXP_SLTCAP_ABP);
 
+    if (dev->cap_present & QEMU_PCIE_SLTCAP_PCP) {
+        pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
+                                   PCI_EXP_SLTCAP_PCP);
+        pci_word_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCTL,
+                                     PCI_EXP_SLTCTL_PCC);
+        pci_word_test_and_set_mask(dev->wmask + pos + PCI_EXP_SLTCTL,
+                                   PCI_EXP_SLTCTL_PCC);
+    }
+
     pci_word_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCTL,
                                  PCI_EXP_SLTCTL_PIC |
                                  PCI_EXP_SLTCTL_AIC);
@@ -327,6 +336,10 @@ void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
 void pcie_cap_slot_reset(PCIDevice *dev)
 {
     uint8_t *exp_cap = dev->config + dev->exp.exp_cap;
+    uint8_t port_type = pcie_cap_get_type(dev);
+
+    assert(port_type == PCI_EXP_TYPE_DOWNSTREAM ||
+           port_type == PCI_EXP_TYPE_ROOT_PORT);
 
     PCIE_DEV_PRINTF(dev, "reset\n");
 
@@ -339,9 +352,27 @@ void pcie_cap_slot_reset(PCIDevice *dev)
                                  PCI_EXP_SLTCTL_PDCE |
                                  PCI_EXP_SLTCTL_ABPE);
     pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTCTL,
-                               PCI_EXP_SLTCTL_PIC_OFF |
                                PCI_EXP_SLTCTL_AIC_OFF);
 
+    if (dev->cap_present & QEMU_PCIE_SLTCAP_PCP) {
+        bool populated;
+        uint16_t pic;
+
+        /* Downstream ports enforce device number 0. */
+        populated = (pci_bridge_get_sec_bus(PCI_BRIDGE(dev))->devices[0] != NULL);
+
+        if (populated) {
+            pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTCTL,
+                                         PCI_EXP_SLTCTL_PCC);
+        } else {
+            pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTCTL,
+                                       PCI_EXP_SLTCTL_PCC);
+        }
+
+        pic = populated ? PCI_EXP_SLTCTL_PIC_ON : PCI_EXP_SLTCTL_PIC_OFF;
+        pci_word_test_and_set_mask(exp_cap + PCI_EXP_SLTCTL, pic);
+     }
+
     pci_word_test_and_clear_mask(exp_cap + PCI_EXP_SLTSTA,
                                  PCI_EXP_SLTSTA_EIS |/* on reset,
                                                         the lock is released */

include/hw/i386/pc.h

@@ -297,6 +297,14 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
             .driver   = "ICH9-LPC",\
             .property = "memory-hotplug-support",\
             .value    = "off",\
+        },{\
+            .driver   = "xio3130-downstream",\
+            .property = COMPAT_PROP_PCP,\
+            .value    = "off",\
+        },{\
+            .driver   = "ioh3420",\
+            .property = COMPAT_PROP_PCP,\
+            .value    = "off",\
         }
  
 #define PC_Q35_COMPAT_1_7 \

include/hw/pci/pci.h

@@ -158,6 +158,9 @@ enum {
     QEMU_PCI_CAP_SHPC = (1 << QEMU_PCI_SHPC_BITNR),
 #define QEMU_PCI_SLOTID_BITNR 6
     QEMU_PCI_CAP_SLOTID = (1 << QEMU_PCI_SLOTID_BITNR),
+    /* PCI Express capability - Power Controller Present */
+#define QEMU_PCIE_SLTCAP_PCP_BITNR 7
+    QEMU_PCIE_SLTCAP_PCP = (1 << QEMU_PCIE_SLTCAP_PCP_BITNR),
 };
 
 #define TYPE_PCI_DEVICE "pci-device"

include/hw/pci/pcie.h

@@ -76,6 +76,8 @@ struct PCIExpressDevice {
     PCIEAERLog aer_log;
 };
 
+#define COMPAT_PROP_PCP "power_controller_present"
+
 /* PCI express capability helper functions */
 int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port);
 int pcie_endpoint_cap_init(PCIDevice *dev, uint8_t offset);

include/hw/pci/pcie_regs.h

@@ -57,6 +57,8 @@
 #define PCI_EXP_SLTCTL_PIC_SHIFT        (ffs(PCI_EXP_SLTCTL_PIC) - 1)
 #define PCI_EXP_SLTCTL_PIC_OFF                          \
     (PCI_EXP_SLTCTL_IND_OFF << PCI_EXP_SLTCTL_PIC_SHIFT)
+#define PCI_EXP_SLTCTL_PIC_ON                          \
+    (PCI_EXP_SLTCTL_IND_ON << PCI_EXP_SLTCTL_PIC_SHIFT)
 
 #define PCI_EXP_SLTCTL_SUPPORTED        \
             (PCI_EXP_SLTCTL_ABPE |      \