[PATCH v4 1/6] xen/igd: get PCH info from host sysfs

The igd_combo_id_infos[] data is out of date with many
devices missing from igd_combo_id_infos[]. For newer
devices not in igd_combo_id_infos[], get the infos from
the host sysfs. If logging is configured, print log
messages displaying the PCH info used for the guest.

Introduce helper function xen_pt_get_host_pch_info() to
facilitate getting the necessary information from sysfs.
Treat failure to get the host PCH device id as an unrecoverable
error that causes guest creation to fail. If access to the host
PCH device revision id fails, print a warning message and use
a default value of 0x1 in that case.

Also, use errp in xen_igd_passthrough_isa_bridge_create()
to set errors from xen_pt_get_host_pch_info() and cleanup
on error path with xen_host_pci_device_put(&s->real_device)
and object_unparent(OBJECT(&d->rom)) for errors when creating
creating the IGD PCH bridge.

Add cleanup with object_unparent(OBJECT(&d->rom)) for errors
when setting up VGA BIOS for GFX passthrough.

Signed-off-by: Chuck Zmudzinski <[email protected]>
---
Changes in v4:
  - re-wrote xen_pt_get_host_pch_info() using functions from
    xen-host-pci-device.h
  - add more error handling to clean up better after if errors occur
  - don't consider failure to get the PCH device revision id a fatal
    error but instead print a warning message and use a default value
    of 0x1

 hw/xen/xen_pt.c          | 10 +++++++++-
 hw/xen/xen_pt_graphics.c | 39 +++++++++++++++++++++++++++++++++++++--
 include/hw/xen/xen_igd.h |  3 ++-
 3 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index 0fe9c0a..c8f08b5 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -862,12 +862,20 @@ static void xen_pt_realize(PCIDevice *d, Error **errp)
         if (*errp) {
             error_append_hint(errp, "Setup VGA BIOS of passthrough"
                               " GFX failed");
+            object_unparent(OBJECT(&d->rom));
             xen_host_pci_device_put(&s->real_device);
             return;
         }
 
         /* Register ISA bridge for passthrough GFX. */
-        xen_igd_passthrough_isa_bridge_create(s, &s->real_device);
+        xen_igd_passthrough_isa_bridge_create(s, &s->real_device, errp);
+        if (*errp) {
+            error_append_hint(errp, "Failed to create PCH bridge"
+                              " for passthrough GFX");
+            object_unparent(OBJECT(&d->rom));
+            xen_host_pci_device_put(&s->real_device);
+            return;
+        }
     }
 
     /* Handle real device's MMIO/PIO BARs */
diff --git a/hw/xen/xen_pt_graphics.c b/hw/xen/xen_pt_graphics.c
index 7df9344..b37f9b7 100644
--- a/hw/xen/xen_pt_graphics.c
+++ b/hw/xen/xen_pt_graphics.c
@@ -2,6 +2,7 @@
  * graphics passthrough
  */
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "hw/xen/xen_pt.h"
 #include "hw/xen/xen_igd.h"
@@ -376,8 +377,33 @@ static void pt_graphics_register_types(void)
 }
 type_init(pt_graphics_register_types)
 
+static void xen_pt_get_host_pch_info(uint16_t *pch_dev_id, uint8_t *pch_rev_id,
+                                     Error **errp)
+{
+    g_autofree XenHostPCIDevice *pch_dev = g_new(XenHostPCIDevice, 1);
+
+    xen_host_pci_device_get(pch_dev, 0, 0, 0x1f, 0, errp);
+    if (*errp) {
+        goto error;
+    }
+
+    *pch_dev_id = pch_dev->device_id;
+
+    if (xen_host_pci_get_byte(pch_dev, PCI_REVISION_ID, pch_rev_id)) {
+        *pch_rev_id = 0x1;
+        warn_report("failed to get host PCH revision for Intel IGD, setting it to 0x1");
+    }
+
+    xen_host_pci_device_put(pch_dev);
+    return;
+
+error:
+    error_append_hint(errp, "failed to get host PCH device for Intel IGD");
+}
+
 void xen_igd_passthrough_isa_bridge_create(XenPCIPassthroughState *s,
-                                           XenHostPCIDevice *dev)
+                                           XenHostPCIDevice *dev,
+                                           Error **errp)
 {
     PCIBus *bus = pci_get_bus(&s->dev);
     struct PCIDevice *bridge_dev;
@@ -394,7 +420,16 @@ void xen_igd_passthrough_isa_bridge_create(XenPCIPassthroughState *s,
         }
     }
 
+    /* Newer devices get PCH infos from host sysfs */
+    if ((pch_dev_id == 0xffff) || !pch_rev_id) {
+        xen_pt_get_host_pch_info(&pch_dev_id, &pch_rev_id, errp);
+    }
+
+    XEN_PT_LOG(&s->dev, "PCH device id: 0x%x\n", pch_dev_id);
+    XEN_PT_LOG(&s->dev, "PCH revision: 0x%x\n", pch_rev_id);
+
     if (pch_dev_id == 0xffff) {
+        error_setg(errp, "failed to get PCH device id");
         return;
     }
 
@@ -406,7 +441,7 @@ void xen_igd_passthrough_isa_bridge_create(XenPCIPassthroughState *s,
      * Note that vendor id is always PCI_VENDOR_ID_INTEL.
      */
     if (!bridge_dev) {
-        fprintf(stderr, "set igd-passthrough-isa-bridge failed!\n");
+        error_setg(errp, "set igd-passthrough-isa-bridge failed!");
         return;
     }
     pci_config_set_device_id(bridge_dev->config, pch_dev_id);
diff --git a/include/hw/xen/xen_igd.h b/include/hw/xen/xen_igd.h
index 7ffca06..da51f09 100644
--- a/include/hw/xen/xen_igd.h
+++ b/include/hw/xen/xen_igd.h
@@ -22,7 +22,8 @@ uint32_t igd_read_opregion(XenPCIPassthroughState *s);
 void xen_igd_reserve_slot(PCIBus *pci_bus);
 void igd_write_opregion(XenPCIPassthroughState *s, uint32_t val);
 void xen_igd_passthrough_isa_bridge_create(XenPCIPassthroughState *s,
-                                           XenHostPCIDevice *dev);
+                                           XenHostPCIDevice *dev,
+                                           Error **errp);
 
 static inline bool is_igd_vga_passthrough(XenHostPCIDevice *dev)
 {
-- 
2.52.0