[PATCH v2] PCI: vmd: Enable Hotplug based on BIOS setting on VMD rootports

[Nirmal Patel <nirmal.patel@linux.intel.com>]

Currently VMD copies root bridge setting to enable Hotplug on its
rootports. This mechanism works fine for Host OS and no issue has
been observed. However in case of VM, all the HyperVisors don't
pass the Hotplug setting to the guest BIOS which results in
assigning default values and disabling Hotplug capability in the
guest which have been observed by many OEMs.

VMD Hotplug can be enabled or disabled based on the VMD rootports'
Hotplug configuration in BIOS. is_hotplug_bridge is set on each
VMD rootport based on Hotplug capable bit in SltCap in probe.c.
Check is_hotplug_bridge and enable or disable native_pcie_hotplug
based on that value.

This patch will make sure that Hotplug is enabled properly in Host
as well as in VM while honoring _OSC settings as well as VMD hotplug
setting.

Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
---
v1->v2: Updating commit message.
---
 drivers/pci/controller/vmd.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 769eedeb8802..e39eaef5549a 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -720,6 +720,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	resource_size_t membar2_offset = 0x2000;
 	struct pci_bus *child;
 	struct pci_dev *dev;
+	struct pci_host_bridge *vmd_bridge;
 	int ret;
 
 	/*
@@ -886,8 +887,16 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	 * and will fail pcie_bus_configure_settings() early. It can instead be
 	 * run on each of the real root ports.
 	 */
-	list_for_each_entry(child, &vmd->bus->children, node)
+	vmd_bridge = to_pci_host_bridge(vmd->bus->bridge);
+	list_for_each_entry(child, &vmd->bus->children, node) {
 		pcie_bus_configure_settings(child);
+		/*
+		 * When Hotplug is enabled on vmd root-port, enable it on vmd
+		 * bridge.
+		 */
+		if (child->self->is_hotplug_bridge)
+			vmd_bridge->native_pcie_hotplug = 1;
+	}
 
 	pci_bus_add_devices(vmd->bus);
 
-- 
2.31.1