On 2019/10/24 上午5:42, Alex Williamson wrote:

On Wed, 23 Oct 2019 21:07:48 +0800
Jason Wang [off-list ref] wrote:

quoted

Add support to parse mdev class id table.

Reviewed-by: Parav Pandit <redacted>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
  drivers/vfio/mdev/vfio_mdev.c     |  2 ++
  scripts/mod/devicetable-offsets.c |  3 +++
  scripts/mod/file2alias.c          | 10 ++++++++++
  3 files changed, 15 insertions(+)

diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index 7b24ee9cb8dd..cb701cd646f0 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c

@@ -125,6 +125,8 @@ static const struct mdev_class_id id_table[] = {
  	{ 0 },
  };
  
+MODULE_DEVICE_TABLE(mdev, id_table);
+

Two questions, first we have:

#define MODULE_DEVICE_TABLE(type, name)                                 \
extern typeof(name) __mod_##type##__##name##_device_table               \
   __attribute__ ((unused, alias(__stringify(name))))

Therefore we're defining __mod_mdev__id_table_device_table with alias
id_table.  When the virtio mdev bus driver is added in 5/6 it uses the
same name value.  I see virtio types all register this way (virtio,
id_table), so I assume there's no conflict, but pci types mostly (not
entirely) seem to use unique names.  Is there a preference to one way
or the other or it simply doesn't matter?

It looks to me that those symbol were local, so it doesn't matter. But 
if you wish I can switch to use unique name.

quoted

  static struct mdev_driver vfio_mdev_driver = {
  	.name	= "vfio_mdev",
  	.probe	= vfio_mdev_probe,

diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index 054405b90ba4..6cbb1062488a 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c

@@ -231,5 +231,8 @@ int main(void)
  	DEVID(wmi_device_id);
  	DEVID_FIELD(wmi_device_id, guid_string);
  
+	DEVID(mdev_class_id);
+	DEVID_FIELD(mdev_class_id, id);
+
  	return 0;
  }

diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index c91eba751804..d365dfe7c718 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c

@@ -1335,6 +1335,15 @@ static int do_wmi_entry(const char *filename, void *symval, char *alias)
  	return 1;
  }
  
+/* looks like: "mdev:cN" */
+static int do_mdev_entry(const char *filename, void *symval, char *alias)
+{
+	DEF_FIELD(symval, mdev_class_id, id);
+
+	sprintf(alias, "mdev:c%02X", id);

A lot of entries call add_wildcard() here, should we?  Sorry for the
basic questions, I haven't played in this code.  Thanks,

It's really good question. My understanding is we won't have a module 
that can deal with all kinds of classes like CLASS_ID_ANY. So there's 
probably no need for the wildcard.

Thanks

Alex

quoted

+	return 1;
+}
+
  /* Does namelen bytes of name exactly match the symbol? */
  static bool sym_is(const char *name, unsigned namelen, const char *symbol)
  {

@@ -1407,6 +1416,7 @@ static const struct devtable devtable[] = {
  	{"typec", SIZE_typec_device_id, do_typec_entry},
  	{"tee", SIZE_tee_client_device_id, do_tee_entry},
  	{"wmi", SIZE_wmi_device_id, do_wmi_entry},
+	{"mdev", SIZE_mdev_class_id, do_mdev_entry},
  };
  
  /* Create MODULE_ALIAS() statements.