diff mbox series

iommu/ipmmu-vmsa: Do not replace bus IOMMU ops on driver init.

Message ID 20170918100444.21878-1-Liviu.Dudau@arm.com
State Superseded
Headers show
Series iommu/ipmmu-vmsa: Do not replace bus IOMMU ops on driver init. | expand

Commit Message

Liviu Dudau Sept. 18, 2017, 10:04 a.m. UTC 
If the IPMMU driver is compiled in the kernel it will replace the
platform bus IOMMU ops on running the ipmmu_init() function, regardless
if there is any IPMMU hardware present or not. This screws up systems
that just want to build a generic kernel that runs on multiple platforms
and use a different IOMMU implementation.

Move the bus_set_iommu() call at the end of the ipmmu_probe() function
when we know that hardware is present. With current IOMMU framework it
should be safe (at least for OF case).

Now that the ipmmu_init() and ipmmu_exit() functions are simple calls to
platform_driver_register() and platform_driver_unregister(), replace
them with the module_platform_driver() macro call.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
 drivers/iommu/ipmmu-vmsa.c | 29 +++++------------------------
 1 file changed, 5 insertions(+), 24 deletions(-)

-- 
2.14.1

Comments

Laurent Pinchart Sept. 19, 2017, 7:07 a.m. UTC | #1 
Hi Liviu,

Thank you for the patch.

On Monday, 18 September 2017 13:04:44 EEST Liviu Dudau wrote:
> If the IPMMU driver is compiled in the kernel it will replace the

> platform bus IOMMU ops on running the ipmmu_init() function, regardless

> if there is any IPMMU hardware present or not. This screws up systems

> that just want to build a generic kernel that runs on multiple platforms

> and use a different IOMMU implementation.

> 

> Move the bus_set_iommu() call at the end of the ipmmu_probe() function

> when we know that hardware is present. With current IOMMU framework it

> should be safe (at least for OF case).


If I recall correctly the issue is that the IPMMU might be probed after bus 
master devices when using the legacy IOMMU DT integration, which the ipmmu-
vmsa driver does on ARM32. Calling bus_set_iommu() from the probe function 
will then result in some devices losing IOMMU support.

> Now that the ipmmu_init() and ipmmu_exit() functions are simple calls to

> platform_driver_register() and platform_driver_unregister(), replace

> them with the module_platform_driver() macro call.

> 

> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

> Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

> ---

>  drivers/iommu/ipmmu-vmsa.c | 29 +++++------------------------

>  1 file changed, 5 insertions(+), 24 deletions(-)

> 

> diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c

> index 2a38aa15be17d..c60569c74678d 100644

> --- a/drivers/iommu/ipmmu-vmsa.c

> +++ b/drivers/iommu/ipmmu-vmsa.c

> @@ -1055,10 +1055,11 @@ static int ipmmu_probe(struct platform_device *pdev)

> ipmmu_device_reset(mmu);

> 

>  	/*

> -	 * We can't create the ARM mapping here as it requires the bus to have

> -	 * an IOMMU, which only happens when bus_set_iommu() is called in

> -	 * ipmmu_init() after the probe function returns.

> +	 * Now that we have validated the presence of the hardware, set

> +	 * the bus IOMMU ops to enable future domain and device setup.

>  	 */

> +	if (!iommu_present(&platform_bus_type))

> +		bus_set_iommu(&platform_bus_type, &ipmmu_ops);

> 

>  	spin_lock(&ipmmu_devices_lock);

>  	list_add(&mmu->list, &ipmmu_devices);


What branch is this patch based on ? ipmmu_devices_lock isn't in mainline.

> @@ -1100,27 +1101,7 @@ static struct platform_driver ipmmu_driver = {

>  	.remove	= ipmmu_remove,

>  };

> 

> -static int __init ipmmu_init(void)

> -{

> -	int ret;

> -

> -	ret = platform_driver_register(&ipmmu_driver);

> -	if (ret < 0)

> -		return ret;

> -

> -	if (!iommu_present(&platform_bus_type))

> -		bus_set_iommu(&platform_bus_type, &ipmmu_ops);

> -

> -	return 0;

> -}

> -

> -static void __exit ipmmu_exit(void)

> -{

> -	return platform_driver_unregister(&ipmmu_driver);

> -}

> -

> -subsys_initcall(ipmmu_init);

> -module_exit(ipmmu_exit);

> +module_platform_driver(ipmmu_driver);

> 

>  MODULE_DESCRIPTION("IOMMU API for Renesas VMSA-compatible IPMMU");

>  MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");


-- 
Regards,

Laurent Pinchart
Liviu Dudau Sept. 19, 2017, 9:45 a.m. UTC | #2 
On Tue, Sep 19, 2017 at 10:07:58AM +0300, Laurent Pinchart wrote:
> Hi Liviu,

> 

> Thank you for the patch.

> 

> On Monday, 18 September 2017 13:04:44 EEST Liviu Dudau wrote:

> > If the IPMMU driver is compiled in the kernel it will replace the

> > platform bus IOMMU ops on running the ipmmu_init() function, regardless

> > if there is any IPMMU hardware present or not. This screws up systems

> > that just want to build a generic kernel that runs on multiple platforms

> > and use a different IOMMU implementation.

> > 

> > Move the bus_set_iommu() call at the end of the ipmmu_probe() function

> > when we know that hardware is present. With current IOMMU framework it

> > should be safe (at least for OF case).

> 

> If I recall correctly the issue is that the IPMMU might be probed after bus 

> master devices when using the legacy IOMMU DT integration, which the ipmmu-

> vmsa driver does on ARM32. Calling bus_set_iommu() from the probe function 

> will then result in some devices losing IOMMU support.


This is on arm64, on the Arm Juno board.

> 

> > Now that the ipmmu_init() and ipmmu_exit() functions are simple calls to

> > platform_driver_register() and platform_driver_unregister(), replace

> > them with the module_platform_driver() macro call.

> > 

> > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

> > Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

> > ---

> >  drivers/iommu/ipmmu-vmsa.c | 29 +++++------------------------

> >  1 file changed, 5 insertions(+), 24 deletions(-)

> > 

> > diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c

> > index 2a38aa15be17d..c60569c74678d 100644

> > --- a/drivers/iommu/ipmmu-vmsa.c

> > +++ b/drivers/iommu/ipmmu-vmsa.c

> > @@ -1055,10 +1055,11 @@ static int ipmmu_probe(struct platform_device *pdev)

> > ipmmu_device_reset(mmu);

> > 

> >  	/*

> > -	 * We can't create the ARM mapping here as it requires the bus to have

> > -	 * an IOMMU, which only happens when bus_set_iommu() is called in

> > -	 * ipmmu_init() after the probe function returns.

> > +	 * Now that we have validated the presence of the hardware, set

> > +	 * the bus IOMMU ops to enable future domain and device setup.

> >  	 */

> > +	if (!iommu_present(&platform_bus_type))

> > +		bus_set_iommu(&platform_bus_type, &ipmmu_ops);

> > 

> >  	spin_lock(&ipmmu_devices_lock);

> >  	list_add(&mmu->list, &ipmmu_devices);

> 

> What branch is this patch based on ? ipmmu_devices_lock isn't in mainline.


drm-next. :)
Looks like things have move forward since I've made the patch before
LPC, will update and resend.

Best regards,
Liviu

> 

> > @@ -1100,27 +1101,7 @@ static struct platform_driver ipmmu_driver = {

> >  	.remove	= ipmmu_remove,

> >  };

> > 

> > -static int __init ipmmu_init(void)

> > -{

> > -	int ret;

> > -

> > -	ret = platform_driver_register(&ipmmu_driver);

> > -	if (ret < 0)

> > -		return ret;

> > -

> > -	if (!iommu_present(&platform_bus_type))

> > -		bus_set_iommu(&platform_bus_type, &ipmmu_ops);

> > -

> > -	return 0;

> > -}

> > -

> > -static void __exit ipmmu_exit(void)

> > -{

> > -	return platform_driver_unregister(&ipmmu_driver);

> > -}

> > -

> > -subsys_initcall(ipmmu_init);

> > -module_exit(ipmmu_exit);

> > +module_platform_driver(ipmmu_driver);

> > 

> >  MODULE_DESCRIPTION("IOMMU API for Renesas VMSA-compatible IPMMU");

> >  MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");

> 

> -- 

> Regards,

> 

> Laurent Pinchart

> 


-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯
Robin Murphy Sept. 19, 2017, 10:47 a.m. UTC | #3 
Hi Laurent,

On 19/09/17 08:07, Laurent Pinchart wrote:
> Hi Liviu,

> 

> Thank you for the patch.

> 

> On Monday, 18 September 2017 13:04:44 EEST Liviu Dudau wrote:

>> If the IPMMU driver is compiled in the kernel it will replace the

>> platform bus IOMMU ops on running the ipmmu_init() function, regardless

>> if there is any IPMMU hardware present or not. This screws up systems

>> that just want to build a generic kernel that runs on multiple platforms

>> and use a different IOMMU implementation.

>>

>> Move the bus_set_iommu() call at the end of the ipmmu_probe() function

>> when we know that hardware is present. With current IOMMU framework it

>> should be safe (at least for OF case).

> 

> If I recall correctly the issue is that the IPMMU might be probed after bus 

> master devices when using the legacy IOMMU DT integration, which the ipmmu-

> vmsa driver does on ARM32. Calling bus_set_iommu() from the probe function 

> will then result in some devices losing IOMMU support.


Yes, that used to be the problem, but since IPMMU uses the generic
bindings and iommu_device_register(), it should now benefit from client
probe-deferral even when it doesn't support of_xlate().

Robin.

>> Now that the ipmmu_init() and ipmmu_exit() functions are simple calls to

>> platform_driver_register() and platform_driver_unregister(), replace

>> them with the module_platform_driver() macro call.

>>

>> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

>> Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

>> ---

>>  drivers/iommu/ipmmu-vmsa.c | 29 +++++------------------------

>>  1 file changed, 5 insertions(+), 24 deletions(-)

>>

>> diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c

>> index 2a38aa15be17d..c60569c74678d 100644

>> --- a/drivers/iommu/ipmmu-vmsa.c

>> +++ b/drivers/iommu/ipmmu-vmsa.c

>> @@ -1055,10 +1055,11 @@ static int ipmmu_probe(struct platform_device *pdev)

>> ipmmu_device_reset(mmu);

>>

>>  	/*

>> -	 * We can't create the ARM mapping here as it requires the bus to have

>> -	 * an IOMMU, which only happens when bus_set_iommu() is called in

>> -	 * ipmmu_init() after the probe function returns.

>> +	 * Now that we have validated the presence of the hardware, set

>> +	 * the bus IOMMU ops to enable future domain and device setup.

>>  	 */

>> +	if (!iommu_present(&platform_bus_type))

>> +		bus_set_iommu(&platform_bus_type, &ipmmu_ops);

>>

>>  	spin_lock(&ipmmu_devices_lock);

>>  	list_add(&mmu->list, &ipmmu_devices);

> 

> What branch is this patch based on ? ipmmu_devices_lock isn't in mainline.

> 

>> @@ -1100,27 +1101,7 @@ static struct platform_driver ipmmu_driver = {

>>  	.remove	= ipmmu_remove,

>>  };

>>

>> -static int __init ipmmu_init(void)

>> -{

>> -	int ret;

>> -

>> -	ret = platform_driver_register(&ipmmu_driver);

>> -	if (ret < 0)

>> -		return ret;

>> -

>> -	if (!iommu_present(&platform_bus_type))

>> -		bus_set_iommu(&platform_bus_type, &ipmmu_ops);

>> -

>> -	return 0;

>> -}

>> -

>> -static void __exit ipmmu_exit(void)

>> -{

>> -	return platform_driver_unregister(&ipmmu_driver);

>> -}

>> -

>> -subsys_initcall(ipmmu_init);

>> -module_exit(ipmmu_exit);

>> +module_platform_driver(ipmmu_driver);

>>

>>  MODULE_DESCRIPTION("IOMMU API for Renesas VMSA-compatible IPMMU");

>>  MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");

>
diff mbox series

Patch

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 2a38aa15be17d..c60569c74678d 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -1055,10 +1055,11 @@  static int ipmmu_probe(struct platform_device *pdev)
 	ipmmu_device_reset(mmu);
 
 	/*
-	 * We can't create the ARM mapping here as it requires the bus to have
-	 * an IOMMU, which only happens when bus_set_iommu() is called in
-	 * ipmmu_init() after the probe function returns.
+	 * Now that we have validated the presence of the hardware, set
+	 * the bus IOMMU ops to enable future domain and device setup.
 	 */
+	if (!iommu_present(&platform_bus_type))
+		bus_set_iommu(&platform_bus_type, &ipmmu_ops);
 
 	spin_lock(&ipmmu_devices_lock);
 	list_add(&mmu->list, &ipmmu_devices);
@@ -1100,27 +1101,7 @@  static struct platform_driver ipmmu_driver = {
 	.remove	= ipmmu_remove,
 };
 
-static int __init ipmmu_init(void)
-{
-	int ret;
-
-	ret = platform_driver_register(&ipmmu_driver);
-	if (ret < 0)
-		return ret;
-
-	if (!iommu_present(&platform_bus_type))
-		bus_set_iommu(&platform_bus_type, &ipmmu_ops);
-
-	return 0;
-}
-
-static void __exit ipmmu_exit(void)
-{
-	return platform_driver_unregister(&ipmmu_driver);
-}
-
-subsys_initcall(ipmmu_init);
-module_exit(ipmmu_exit);
+module_platform_driver(ipmmu_driver);
 
 MODULE_DESCRIPTION("IOMMU API for Renesas VMSA-compatible IPMMU");
 MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");