Hi Sinan,
On 03/10/2016 06:13 PM, Sinan Kaya wrote:

On 3/10/2016 5:11 AM, Eric Auger wrote:

quoted

Hi Sinan,
On 03/08/2016 04:33 PM, Sinan Kaya wrote:

quoted

The  code is using the compatible DT string to associate a reset driver with
the actual device itself. The compatible string does not exist on ACPI
based systems. HID is the unique identifier for a device driver instead.
The change allows a driver to register with DT compatible string or ACPI
HID and then match the object with one of these conditions.

Rules for loading the reset driver are as follow:
- ACPI HID needs match for ACPI systems
- DT compat needs to match for OF systems

Tested-by: Eric Auger <redacted> (device tree only)
Tested-by: Shanker Donthineni <redacted> (ACPI only)
Signed-off-by: Sinan Kaya <redacted>
---
 .../vfio/platform/reset/vfio_platform_amdxgbe.c    |   4 +-
 .../platform/reset/vfio_platform_calxedaxgmac.c    |   4 +-
 drivers/vfio/platform/vfio_platform_common.c       | 112 +++++++++++++++++----
 drivers/vfio/platform/vfio_platform_private.h      |  43 ++++----
 4 files changed, 125 insertions(+), 38 deletions(-)

diff --git a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
index d4030d0..170dcf5 100644
--- a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
+++ b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c

@@ -119,7 +119,9 @@ int vfio_platform_amdxgbe_reset(struct vfio_platform_device *vdev)
 	return 0;
 }
 
-module_vfio_reset_handler("amd,xgbe-seattle-v1a", vfio_platform_amdxgbe_reset);
+module_vfio_reset_handler("amd,xgbe-seattle-v1a", NULL,
+			  vfio_platform_amdxgbe_reset);
+VFIO_PLATFORM_MODULE_ALIAS("amd,xgbe-seattle-v1a");

Looks the other overridden MODULE_ALIAS have a naming like
MODULE_ALIAS_something? what about MODULE_ALIAS_VFIO_PLATFORM_RESET?
not very compact but maybe closer to what it stands for.

alright, I'll follow that.

quoted

quoted

 
 MODULE_VERSION("0.1");
 MODULE_LICENSE("GPL v2");

diff --git a/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c b/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
index e3d3d94..635c6e0 100644
--- a/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
+++ b/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c

@@ -77,7 +77,9 @@ int vfio_platform_calxedaxgmac_reset(struct vfio_platform_device *vdev)
 	return 0;
 }
 
-module_vfio_reset_handler("calxeda,hb-xgmac", vfio_platform_calxedaxgmac_reset);
+module_vfio_reset_handler("calxeda,hb-xgmac", NULL,
+			  vfio_platform_calxedaxgmac_reset);
+VFIO_PLATFORM_MODULE_ALIAS("calxeda,hb-xgmac");
 
 MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL v2");

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 418cdd9..c758e72 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c

@@ -13,6 +13,7 @@
  */
 
 #include <linux/device.h>
+#include <linux/acpi.h>
 #include <linux/iommu.h>
 #include <linux/module.h>
 #include <linux/mutex.h>

@@ -31,14 +32,22 @@ static LIST_HEAD(reset_list);
 static DEFINE_MUTEX(driver_lock);
 
 static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
-					struct module **module)
+				  const char *acpihid, struct module **module)
 {
 	struct vfio_platform_reset_node *iter;
 	vfio_platform_reset_fn_t reset_fn = NULL;
 
 	mutex_lock(&driver_lock);
 	list_for_each_entry(iter, &reset_list, link) {
-		if (!strcmp(iter->compat, compat) &&
+		if (acpihid && iter->acpihid &&
+		    !strcmp(iter->acpihid, acpihid) &&
+			try_module_get(iter->owner)) {
+			*module = iter->owner;
+			reset_fn = iter->reset;
+			break;
+		}
+		if (compat && iter->compat &&
+		    !strcmp(iter->compat, compat) &&
 			try_module_get(iter->owner)) {
 			*module = iter->owner;
 			reset_fn = iter->reset;

@@ -49,15 +58,30 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
 	return reset_fn;
 }
 
-static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
+static int vfio_platform_get_reset(struct vfio_platform_device *vdev)

What is the point returning a value here? See my comment at the end.

I was trying to do some error handling here. If a driver does not have a
reset implementation, we are letting it go right now. 

I think we need to make reset driver a requirement. Mark Rutland reminded me 
that I need a reset driver. 

I did not think about it during implementation and I have not seen any 
warnings like you said.

the warning currently is emitted on vfio_platform_open/release:
dev_warn(vdev->device, "no reset function found!\n");

quoted

quoted

 {
-	vdev->reset = vfio_platform_lookup_reset(vdev->compat,
-						&vdev->reset_module);
-	if (!vdev->reset) {
-		request_module("vfio-reset:%s", vdev->compat);
-		vdev->reset = vfio_platform_lookup_reset(vdev->compat,
-							 &vdev->reset_module);
-	}

quoted

quoted

 
-	vfio_platform_get_reset(vdev);
+	ret = vfio_platform_get_reset(vdev);
+	if (ret) {
+		iommu_group_put(group);
+		return ret;
+	}

This change is not related to your commit message. Also here you change
the use model of VFIO platform and forbid any usage if no reset module
is available, right? I don't think this is something we discussed and I
think it removes some flexibility. Currently a warning is emitted in
case we don't have a reset function.

Well, I haven't seen that warning during testing. I was trying to be more 
proactive.

Thank you for that. Personally I agree to proceed with the proposed
change, ie. forbid vfio platform driver to be used if there is no reset
function found but this should be in a separate patch with explicit
commit mesg and you should remove dev_warn & related dead code.

Best Regards

Eric

I'm fine removing these checks but not having a reset driver needs a really
big warning here.

quoted

Best Regards

Eric

quoted