[PATCH v2 1/3] xen/igd: get PCH info from host sysfs

[Chuck Zmudzinski <brchuckz@xxxxxxx>]

The igd_combo_id_infos[] data is more than 10 years
out of date with many Intel IGD devices missing from
igd_combo_id_infos[]. This means that many devices
that could be supported will not work with the
current implementation.

For newer devices not listed in igd_combo_id_infos[],
get infos from the host sysfs to enable support for the
newer devices not listed in igd_combo_id_infos[].

Introduce the helper function xen_pt_get_host_pch_info
to facilitate getting the necessary information from
sysfs.

Also, use errp in xen_igd_passthrough_isa_bridge_create
to set errors from xen_pt_get_host_pch_info.

Signed-off-by: Chuck Zmudzinski <brchuckz@xxxxxxx>
---
Changes in v2:
  - call error_setg* after closing files instead of before closing
    files
  - in last line of commit message change "to propagate errors" to
    "to set errors"
  - add stable to Cc list

 hw/xen/xen_pt.c          |  2 +-
 hw/xen/xen_pt_graphics.c | 82 ++++++++++++++++++++++++++++++++++++++--
 include/hw/xen/xen_igd.h |  3 +-
 3 files changed, 82 insertions(+), 5 deletions(-)

diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index 0fe9c0a..474606e 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -867,7 +867,7 @@ static void xen_pt_realize(PCIDevice *d, Error **errp)
         }
 
         /* 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);
     }
 
     /* 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..2ef941e 100644
--- a/hw/xen/xen_pt_graphics.c
+++ b/hw/xen/xen_pt_graphics.c
@@ -376,8 +376,75 @@ static void pt_graphics_register_types(void)
 }
 type_init(pt_graphics_register_types)
 
+static void xen_pt_get_host_pch_info(PCIDevice *dev, uint16_t *pch_dev_id,
+                                 uint8_t *pch_rev_id, Error **errp)
+{
+    FILE *fp1, *fp2;
+    char *endptr;
+    char device_id[7], rev[5];
+    size_t len;
+    const char *device = "/sys/bus/pci/devices/0000:00:1f.0/device";
+    const char *revision = "/sys/bus/pci/devices/0000:00:1f.0/revision";
+    unsigned long val;
+
+    fp1 = fopen(device, "r");
+    if (fp1 == NULL) {
+        error_setg_errno(errp, errno, "Cannot open %s", device);
+        return;
+    }
+    fp2 = fopen(revision, "r");
+    if (fp2 == NULL) {
+        fclose(fp1);
+        error_setg_errno(errp, errno, "Cannot open %s", revision);
+        return;
+    }
+
+    len = fread(device_id, 1, 7, fp1);
+    if (!len) {
+        fclose(fp1);
+        fclose(fp2);
+        error_setg(errp, "Cannot read %s", device);
+        return;
+    }
+    len = fread(rev, 1, 5, fp2);
+    if (!len) {
+        fclose(fp1);
+        fclose(fp2);
+        error_setg(errp, "Cannot read %s", revision);
+        return;
+    }
+    fclose(fp1);
+    fclose(fp2);
+
+    val = strtoul(device_id, &endptr, 16);
+    if (val > 0xffff) {
+        error_setg(errp, "PCH device id is out of range: 0x%lx", val);
+        return;
+    }
+    if ((endptr > device_id) && (errno != ERANGE) &&
+        (errno != EINVAL)) {
+        *pch_dev_id = (uint16_t)val;
+    } else {
+        error_setg_errno(errp, errno, "device id strtoul "
+                                      "conversion failed");
+        return;
+    }
+    val = strtoul(rev, &endptr, 16);
+    if (val > 0xff) {
+        error_setg(errp, "PCH revision is out of range: 0x%lx", val);
+        return;
+    }
+    if ((endptr > rev) && (errno != ERANGE) && (errno != EINVAL)) {
+        *pch_rev_id = (uint8_t)val;
+    } else {
+        error_setg_errno(errp, errno, "revision strtoul "
+                                      "conversion failed");
+    }
+}
+
 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 +461,16 @@ void 
xen_igd_passthrough_isa_bridge_create(XenPCIPassthroughState *s,
         }
     }
 
-    if (pch_dev_id == 0xffff) {
+    /* Newer devices get PCH infos from host sysfs */
+    if ((pch_dev_id == 0xffff) || !pch_rev_id) {
+        xen_pt_get_host_pch_info(&s->dev, &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) || !pch_rev_id) {
+        error_setg(errp, "failed to get PCH device id or revision");
         return;
     }
 
@@ -406,7 +482,7 @@ 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