pci: acpi hotplug: rename x-native-hotplug to x-do-not-expose-native-hotplug-cap

When ACPI PCI hotplug for Q35 was introduced (6.1), it was implemented
by hiding HPC capability on PCIE slot. That however led to a number of
regressions and to fix it, it was decided to keep HPC cap exposed
in ACPI PCI hotplug case and force guest in ACPI PCI hotplug mode
by other means [1].

That reduced meaning of x-native-hotplug to a compat knob [2] for
broken 6.1 machine type.
Rename property to match its current purpose.

1) 211afe5c69 (hw/i386/acpi-build: Deny control on PCIe Native Hot-plug in _OSC)
2) c318bef762 (hw/acpi/ich9: Add compat prop to keep HPC bit set for 6.1 machine type)

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20230112140312.3096331-10-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 83c57c6eb134820bf8e7ef3bff59c73d9b70a52f..66cd718b708195e924476cbc449570404222d844 100644 (file)
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -257,8 +257,9 @@ static void pc_q35_init(MachineState *machine)
                                                  NULL);
 
     if (!keep_pci_slot_hpc && acpi_pcihp) {
-        object_register_sugar_prop(TYPE_PCIE_SLOT, "x-native-hotplug",
-                                   "false", true);
+        object_register_sugar_prop(TYPE_PCIE_SLOT,
+                                   "x-do-not-expose-native-hotplug-cap",
+                                   "true", true);
     }
 
     /* irq lines */

diff --git a/hw/pci-bridge/gen_pcie_root_port.c b/hw/pci-bridge/gen_pcie_root_port.c
index 20099a8ae31afa3ecf7a4740dfe9d094a448e232..1ce4e7bebae7ef6719d9ec932e132ba04b69fe73 100644 (file)
--- a/hw/pci-bridge/gen_pcie_root_port.c
+++ b/hw/pci-bridge/gen_pcie_root_port.c
@@ -87,7 +87,12 @@ static void gen_rp_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    if (grp->res_reserve.io == -1 && s->hotplug && !s->native_hotplug) {
+    /*
+     * reserving IO space led to worse issues in 6.1, when this hunk was
+     * introduced. (see commit: 211afe5c69b59). Keep this broken for 6.1
+     * machine type ABI compatibility only
+     */
+    if (s->hide_native_hotplug_cap && grp->res_reserve.io == -1 && s->hotplug) {
         grp->res_reserve.io = GEN_PCIE_ROOT_DEFAULT_IO_RANGE;
     }
     int rc = pci_bridge_qemu_reserve_cap_init(d, 0,

diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 68a62da0b5704080495a89f43e3cbcf62e415653..924fdabd157e89c2248bf0151efee5c402178682 100644 (file)
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -611,11 +611,11 @@ void pcie_cap_slot_init(PCIDevice *dev, PCIESlot *s)
                                PCI_EXP_SLTCAP_ABP);
 
     /*
-     * Enable native hot-plug on all hot-plugged bridges unless
-     * hot-plug is disabled on the slot.
+     * Expose native hot-plug on all bridges if hot-plug is enabled on the slot.
+     * (unless broken 6.1 ABI is enforced for compat reasons)
      */
     if (s->hotplug &&
-        (s->native_hotplug || DEVICE(dev)->hotplugged)) {
+        (!s->hide_native_hotplug_cap || DEVICE(dev)->hotplugged)) {
         pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
                                    PCI_EXP_SLTCAP_HPS |
                                    PCI_EXP_SLTCAP_HPC);

diff --git a/hw/pci/pcie_port.c b/hw/pci/pcie_port.c
index 687e4e763a9632e63ff607ea0e9dcf75aa6f7b42..65a397ad23db416be12c6d9d699846aa4648fdd0 100644 (file)
--- a/hw/pci/pcie_port.c
+++ b/hw/pci/pcie_port.c
@@ -173,7 +173,8 @@ 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_BOOL("x-native-hotplug", PCIESlot, native_hotplug, true),
+    DEFINE_PROP_BOOL("x-do-not-expose-native-hotplug-cap", PCIESlot,
+                     hide_native_hotplug_cap, false),
     DEFINE_PROP_END_OF_LIST()
 };
 

diff --git a/include/hw/pci/pcie_port.h b/include/hw/pci/pcie_port.h
index fd484afb30211a6ba323de233f2cd90333c24903..6c40e3733fd391a3de14bedf8ea382a552f6cfc0 100644 (file)
--- a/include/hw/pci/pcie_port.h
+++ b/include/hw/pci/pcie_port.h
@@ -63,7 +63,8 @@ struct PCIESlot {
     /* Indicates whether any type of hot-plug is allowed on the slot */
     bool        hotplug;
 
-    bool        native_hotplug;
+    /* broken ACPI hotplug compat knob to preserve 6.1 ABI intact */
+    bool        hide_native_hotplug_cap;
 
     QLIST_ENTRY(PCIESlot) next;
 };