[qemu,v5,2/3] hw/arm/sysbus-fdt: Allow device matching with DT compatible value

Commit Message

Geert Uytterhoeven Sept. 27, 2018, 11:54 a.m. UTC

From: Auger Eric <[e-mail]>

Up to now we have relied on the device type to identify a device tree
node creation function.  Since we would like the vfio-platform device to
be instantiable with different compatible strings we introduce the
capability to specialize the node creation depending on actual
compatible value.

NodeCreationPair is renamed into BindingEntry. The struct is enhanced
with compat and match_fn() fields.  We introduce a new matching function
adapted to the vfio-platform generic device.

Soon, the AMD XGBE can be instantiated with either manner, i.e.:

    -device vfio-amd-xgbe,host=e0900000.xgmac

or using the new option line:

    -device vfio-platform,host=e0900000.xgmac

Signed-off-by: Eric Auger <[e-mail]>
[geert: Match using compatible values in sysfs instead of user-supplied
	manufacturer/model options, reword]
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Eric Auger <[e-mail]>
Tested-by: Eric Auger <[e-mail]>
---
v5:
  - s/instantiatable/instantiable/,
  - Add Reviewed-by,

v4:
  - Add Tested-by (with amd-xgbe),
  - s/From now on/Soon/ in patch description,

v3:
  - Match using the compatible values from sysfs instead of using
    user-supplied manufacturer and model options,
  - Reword patch description,
  - Drop RFC state,

v2:
  - No changes,

v1:
  - No changes,

v0:
  - Original version from Eric.
---
 hw/arm/sysbus-fdt.c | 61 ++++++++++++++++++++++++++++++++++-----------
 1 file changed, 47 insertions(+), 14 deletions(-)

Comments

Thomas Huth Nov. 5, 2018, 9:17 a.m. UTC | #1

On 2018-09-27 13:54, Geert Uytterhoeven wrote:
> From: Auger Eric <[e-mail]>
> 
> Up to now we have relied on the device type to identify a device tree
> node creation function.  Since we would like the vfio-platform device to
> be instantiable with different compatible strings we introduce the
> capability to specialize the node creation depending on actual
> compatible value.
> 
> NodeCreationPair is renamed into BindingEntry. The struct is enhanced
> with compat and match_fn() fields.  We introduce a new matching function
> adapted to the vfio-platform generic device.
> 
> Soon, the AMD XGBE can be instantiated with either manner, i.e.:
> 
>     -device vfio-amd-xgbe,host=e0900000.xgmac
> 
> or using the new option line:
> 
>     -device vfio-platform,host=e0900000.xgmac
> 
> Signed-off-by: Eric Auger <[e-mail]>
> [geert: Match using compatible values in sysfs instead of user-supplied
> 	manufacturer/model options, reword]
> Signed-off-by: Geert Uytterhoeven <[e-mail]>
> Reviewed-by: Eric Auger <[e-mail]>
> Tested-by: Eric Auger <[e-mail]>

scripts/device-crash-test reports a new "crash" with current QEMU master
branch, where QEMU aborts like this:

aarch64-softmmu/qemu-system-aarch64 -S -machine virt-2.9,accel=tcg
-device ramfb
hw/arm/sysbus-fdt.c:422:vfio_platform_match: Object 0x564cf9ae8f80 is
not an instance of type vfio-platform
Aborted (core dumped)

I think it is likely due to this patch here ... any chance that you
could make this a little bit more user friendly instead of aborting the
hard way here?

 Thanks,
  Thomas

Eric Auger Nov. 5, 2018, 9:39 a.m. UTC | #2

Hi Thomas,

On 11/5/18 10:17 AM, Thomas Huth wrote:
> On 2018-09-27 13:54, Geert Uytterhoeven wrote:
>> From: Auger Eric <[e-mail]>
>>
>> Up to now we have relied on the device type to identify a device tree
>> node creation function.  Since we would like the vfio-platform device to
>> be instantiable with different compatible strings we introduce the
>> capability to specialize the node creation depending on actual
>> compatible value.
>>
>> NodeCreationPair is renamed into BindingEntry. The struct is enhanced
>> with compat and match_fn() fields.  We introduce a new matching function
>> adapted to the vfio-platform generic device.
>>
>> Soon, the AMD XGBE can be instantiated with either manner, i.e.:
>>
>>     -device vfio-amd-xgbe,host=e0900000.xgmac
>>
>> or using the new option line:
>>
>>     -device vfio-platform,host=e0900000.xgmac
>>
>> Signed-off-by: Eric Auger <[e-mail]>
>> [geert: Match using compatible values in sysfs instead of user-supplied
>> 	manufacturer/model options, reword]
>> Signed-off-by: Geert Uytterhoeven <[e-mail]>
>> Reviewed-by: Eric Auger <[e-mail]>
>> Tested-by: Eric Auger <[e-mail]>
> 
> scripts/device-crash-test reports a new "crash" with current QEMU master
> branch, where QEMU aborts like this:
> 
> aarch64-softmmu/qemu-system-aarch64 -S -machine virt-2.9,accel=tcg
> -device ramfb
> hw/arm/sysbus-fdt.c:422:vfio_platform_match: Object 0x564cf9ae8f80 is
> not an instance of type vfio-platform
> Aborted (core dumped)
> 
> I think it is likely due to this patch here ... any chance that you
> could make this a little bit more user friendly instead of aborting the
> hard way here?

thank you for spotting the bug. We should use object_dynamic_cast() to
test if the device is a VFIO_PLATFORM one.

I will prepare a patch.

Thanks

Eric
> 
>  Thanks,
>   Thomas
>

Patch

diff --git a/hw/arm/sysbus-fdt.c b/hw/arm/sysbus-fdt.c
index 43d6a7bb48ddc351..0e24c803a1c2c734 100644
--- a/hw/arm/sysbus-fdt.c
+++ b/hw/arm/sysbus-fdt.c
@@ -50,11 +50,13 @@  typedef struct PlatformBusFDTData {
     PlatformBusDevice *pbus;
 } PlatformBusFDTData;
 
-/* struct that associates a device type name and a node creation function */
-typedef struct NodeCreationPair {
+/* struct that allows to match a device and create its FDT node */
+typedef struct BindingEntry {
     const char *typename;
-    int (*add_fdt_node_fn)(SysBusDevice *sbdev, void *opaque);
-} NodeCreationPair;
+    const char *compat;
+    int  (*add_fn)(SysBusDevice *sbdev, void *opaque);
+    bool (*match_fn)(SysBusDevice *sbdev, const struct BindingEntry *combo);
+} BindingEntry;
 
 /* helpers */
 
@@ -413,6 +415,27 @@  static int add_amd_xgbe_fdt_node(SysBusDevice *sbdev, void *opaque)
     return 0;
 }
 
+/* DT compatible matching */
+static bool vfio_platform_match(SysBusDevice *sbdev,
+                                const BindingEntry *entry)
+{
+    VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(sbdev);
+    const char *compat;
+    unsigned int n;
+
+    for (n = vdev->num_compat, compat = vdev->compat; n > 0;
+         n--, compat += strlen(compat) + 1) {
+        if (!strcmp(entry->compat, compat)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+#define VFIO_PLATFORM_BINDING(compat, add_fn) \
+    {TYPE_VFIO_PLATFORM, (compat), (add_fn), vfio_platform_match}
+
 #endif /* CONFIG_LINUX */
 
 static int no_fdt_node(SysBusDevice *sbdev, void *opaque)
@@ -420,14 +443,23 @@  static int no_fdt_node(SysBusDevice *sbdev, void *opaque)
     return 0;
 }
 
-/* list of supported dynamic sysbus devices */
-static const NodeCreationPair add_fdt_node_functions[] = {
+/* Device type based matching */
+static bool type_match(SysBusDevice *sbdev, const BindingEntry *entry)
+{
+    return !strcmp(object_get_typename(OBJECT(sbdev)), entry->typename);
+}
+
+#define TYPE_BINDING(type, add_fn) {(type), NULL, (add_fn), type_match}
+
+/* list of supported dynamic sysbus bindings */
+static const BindingEntry bindings[] = {
 #ifdef CONFIG_LINUX
-    {TYPE_VFIO_CALXEDA_XGMAC, add_calxeda_midway_xgmac_fdt_node},
-    {TYPE_VFIO_AMD_XGBE, add_amd_xgbe_fdt_node},
+    TYPE_BINDING(TYPE_VFIO_CALXEDA_XGMAC, add_calxeda_midway_xgmac_fdt_node),
+    TYPE_BINDING(TYPE_VFIO_AMD_XGBE, add_amd_xgbe_fdt_node),
+    VFIO_PLATFORM_BINDING("amd,xgbe-seattle-v1a", add_amd_xgbe_fdt_node),
 #endif
-    {TYPE_RAMFB_DEVICE, no_fdt_node},
-    {"", NULL}, /* last element */
+    TYPE_BINDING(TYPE_RAMFB_DEVICE, no_fdt_node),
+    TYPE_BINDING("", NULL), /* last element */
 };
 
 /* Generic Code */
@@ -446,10 +478,11 @@  static void add_fdt_node(SysBusDevice *sbdev, void *opaque)
 {
     int i, ret;
 
-    for (i = 0; i < ARRAY_SIZE(add_fdt_node_functions); i++) {
-        if (!strcmp(object_get_typename(OBJECT(sbdev)),
-                    add_fdt_node_functions[i].typename)) {
-            ret = add_fdt_node_functions[i].add_fdt_node_fn(sbdev, opaque);
+    for (i = 0; i < ARRAY_SIZE(bindings); i++) {
+        const BindingEntry *iter = &bindings[i];
+
+        if (iter->match_fn(sbdev, iter)) {
+            ret = iter->add_fn(sbdev, opaque);
             assert(!ret);
             return;
         }