[PULL 04/21] vfio/igd: Move LPC bridge initialization to a separate function

["Cédric Le Goater" <clg@redhat.com>]

From: Tomita Moeko <tomitamoeko@gmail.com>

A new option will soon be introduced to decouple the LPC bridge/Host
bridge ID quirk from legacy mode. To prepare for this, move the LPC
bridge initialization into a separate function.

Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Corvin Köhne <c.koehne@beckhoff.com>
Link: https://lore.kernel.org/qemu-devel/20250306180131.32970-5-tomitamoeko@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/igd.c | 122 +++++++++++++++++++++++++++++---------------------
 1 file changed, 70 insertions(+), 52 deletions(-)

diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index 113ad56ad4206e29198717d944ffe944e1c2e27c..7feed7dfa920725d1d550b9225c7075453bf7b88 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -351,6 +351,72 @@ static int vfio_pci_igd_lpc_init(VFIOPCIDevice *vdev,
     return ret;
 }
 
+static bool vfio_pci_igd_setup_lpc_bridge(VFIOPCIDevice *vdev, Error **errp)
+{
+    g_autofree struct vfio_region_info *host = NULL;
+    g_autofree struct vfio_region_info *lpc = NULL;
+    PCIDevice *lpc_bridge;
+    int ret;
+
+    /*
+     * Copying IDs or creating new devices are not supported on hotplug
+     */
+    if (vdev->pdev.qdev.hotplugged) {
+        error_setg(errp, "IGD LPC is not supported on hotplugged device");
+        return false;
+    }
+
+    /*
+     * We need to create an LPC/ISA bridge at PCI bus address 00:1f.0 that we
+     * can stuff host values into, so if there's already one there and it's not
+     * one we can hack on, this quirk is no-go.  Sorry Q35.
+     */
+    lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
+                                 0, PCI_DEVFN(0x1f, 0));
+    if (lpc_bridge && !object_dynamic_cast(OBJECT(lpc_bridge),
+                                           "vfio-pci-igd-lpc-bridge")) {
+        error_setg(errp,
+                   "Cannot create LPC bridge due to existing device at 1f.0");
+        return false;
+    }
+
+    /*
+     * Check whether we have all the vfio device specific regions to
+     * support LPC quirk (added in Linux v4.6).
+     */
+    ret = vfio_get_dev_region_info(&vdev->vbasedev,
+                        VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
+                        VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG, &lpc);
+    if (ret) {
+        error_setg(errp, "IGD LPC bridge access is not supported by kernel");
+        return false;
+    }
+
+    ret = vfio_get_dev_region_info(&vdev->vbasedev,
+                        VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
+                        VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG, &host);
+    if (ret) {
+        error_setg(errp, "IGD host bridge access is not supported by kernel");
+        return false;
+    }
+
+    /* Create/modify LPC bridge */
+    ret = vfio_pci_igd_lpc_init(vdev, lpc);
+    if (ret) {
+        error_setg(errp, "Failed to create/modify LPC bridge for IGD");
+        return false;
+    }
+
+    /* Stuff some host values into the VM PCI host bridge */
+    ret = vfio_pci_igd_host_init(vdev, host);
+    if (ret) {
+        error_setg(errp, "Failed to modify host bridge for IGD");
+        return false;
+    }
+
+    return true;
+}
+
 #define IGD_GGC_MMIO_OFFSET     0x108040
 #define IGD_BDSM_MMIO_OFFSET    0x1080C0
 
@@ -419,9 +485,6 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
 void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
 {
     g_autofree struct vfio_region_info *rom = NULL;
-    g_autofree struct vfio_region_info *host = NULL;
-    g_autofree struct vfio_region_info *lpc = NULL;
-    PCIDevice *lpc_bridge;
     int ret, gen;
     uint64_t gms_size;
     uint64_t *bdsm_size;
@@ -440,20 +503,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         return;
     }
 
-    /*
-     * We need to create an LPC/ISA bridge at PCI bus address 00:1f.0 that we
-     * can stuff host values into, so if there's already one there and it's not
-     * one we can hack on, legacy mode is no-go.  Sorry Q35.
-     */
-    lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
-                                 0, PCI_DEVFN(0x1f, 0));
-    if (lpc_bridge && !object_dynamic_cast(OBJECT(lpc_bridge),
-                                           "vfio-pci-igd-lpc-bridge")) {
-        error_report("IGD device %s cannot support legacy mode due to existing "
-                     "devices at address 1f.0", vdev->vbasedev.name);
-        return;
-    }
-
     /*
      * IGD is not a standard, they like to change their specs often.  We
      * only attempt to support back to SandBridge and we hope that newer
@@ -490,28 +539,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         return;
     }
 
-    /*
-     * Check whether we have all the vfio device specific regions to
-     * support legacy mode (added in Linux v4.6).  If not, bail.
-     */
-    ret = vfio_get_dev_region_info(&vdev->vbasedev,
-                        VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
-                        VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG, &host);
-    if (ret) {
-        error_report("IGD device %s does not support host bridge access,"
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
-    }
-
-    ret = vfio_get_dev_region_info(&vdev->vbasedev,
-                        VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
-                        VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG, &lpc);
-    if (ret) {
-        error_report("IGD device %s does not support LPC bridge access,"
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
-    }
-
     gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
 
     /*
@@ -533,19 +560,10 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         return;
     }
 
-    /* Create our LPC/ISA bridge */
-    ret = vfio_pci_igd_lpc_init(vdev, lpc);
-    if (ret) {
-        error_report("IGD device %s failed to create LPC bridge, "
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
-    }
-
-    /* Stuff some host values into the VM PCI host bridge */
-    ret = vfio_pci_igd_host_init(vdev, host);
-    if (ret) {
-        error_report("IGD device %s failed to modify host bridge, "
-                     "legacy mode disabled", vdev->vbasedev.name);
+    /* Setup LPC bridge / Host bridge PCI IDs */
+    if (!vfio_pci_igd_setup_lpc_bridge(vdev, &err)) {
+        error_append_hint(&err, "IGD legacy mode disabled\n");
+        error_report_err(err);
         return;
     }
 
-- 
2.48.1