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[PATCH V9 6/9] vfio: platform: call _RST method when using ACPI

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  [PATCH V9 6/9] vfio: platform: call _RST method when using ACPI Sinan Kaya <okaya@codeaurora.org> - 2016-07-14 04:10 +0200
    Re: [PATCH V9 6/9] vfio: platform: call _RST method when using ACPI Alex Williamson <alex.williamson@redhat.com> - 2016-07-15 00:10 +0200
      Re: [PATCH V9 6/9] vfio: platform: call _RST method when using ACPI Sinan Kaya <okaya@codeaurora.org> - 2016-07-16 03:10 +0200

#1442993 — [PATCH V9 6/9] vfio: platform: call _RST method when using ACPI

The device tree code checks for the presence of a reset driver and calls
the of_reset function pointer by looking up the reset driver as a module.

ACPI defines _RST method to perform device level reset. After the _RST
method is executed, the OS can resume using the device. _RST method is
expected to stop DMA transfers and IRQs.

This patch introduces two functions as vfio_platform_acpi_has_reset and
vfio_platform_acpi_call_reset. The has reset method is used to declare
reset capability via the ioctl flag VFIO_DEVICE_FLAGS_RESET. The call
reset function is used to execute the _RST ACPI method.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/vfio/platform/vfio_platform_common.c | 52 +++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 03483c2..2d9c905 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -28,6 +28,8 @@
 #define DRIVER_AUTHOR   "Antonios Motakis <a.motakis@virtualopensystems.com>"
 #define DRIVER_DESC     "VFIO platform base module"
 
+#define VFIO_PLATFORM_IS_ACPI(vdev) ((vdev)->acpihid != NULL)
+
 static LIST_HEAD(reset_list);
 static DEFINE_MUTEX(driver_lock);
 
@@ -77,13 +79,55 @@ static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
 #endif
 }
 
+static inline
+int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
+				  const char **extra_dbg)
+{
+#ifdef CONFIG_ACPI
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct device *dev = vdev->device;
+	acpi_handle handle = ACPI_HANDLE(dev);
+	acpi_status acpi_ret;
+
+	acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, &buffer);
+	if (ACPI_FAILURE(acpi_ret)) {
+		if (extra_dbg)
+			*extra_dbg = acpi_format_exception(acpi_ret);
+		return -EINVAL;
+	}
+
+	return 0;
+#else
+	return -ENOENT;
+#endif
+}
+
+static inline
+bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
+{
+#ifdef CONFIG_ACPI
+	struct device *dev = vdev->device;
+	acpi_handle handle = ACPI_HANDLE(dev);
+
+	return acpi_has_method(handle, "_RST");
+#else
+	return false;
+#endif
+}
+
 static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
 {
+	if (VFIO_PLATFORM_IS_ACPI(vdev))
+		return vfio_platform_acpi_has_reset(vdev);
+
 	return vdev->of_reset ? true : false;
 }
 
 static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
 {
+	if (VFIO_PLATFORM_IS_ACPI(vdev))
+		return;
+
 	vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
 						    &vdev->reset_module);
 	if (!vdev->of_reset) {
@@ -95,6 +139,9 @@ static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
 
 static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
 {
+	if (VFIO_PLATFORM_IS_ACPI(vdev))
+		return;
+
 	if (vdev->of_reset)
 		module_put(vdev->reset_module);
 }
@@ -170,7 +217,10 @@ static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
 static int vfio_platform_call_reset(struct vfio_platform_device *vdev,
 				    const char **extra_dbg)
 {
-	if (vdev->of_reset) {
+	if (VFIO_PLATFORM_IS_ACPI(vdev)) {
+		dev_info(vdev->device, "reset\n");
+		return vfio_platform_acpi_call_reset(vdev, extra_dbg);
+	} else if (vdev->of_reset) {
 		dev_info(vdev->device, "reset\n");
 		return vdev->of_reset(vdev);
 	}
-- 
1.8.2.1

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#1443806

On Wed, 13 Jul 2016 22:06:32 -0400
Sinan Kaya <okaya@codeaurora.org> wrote:

> The device tree code checks for the presence of a reset driver and calls
> the of_reset function pointer by looking up the reset driver as a module.
> 
> ACPI defines _RST method to perform device level reset. After the _RST
> method is executed, the OS can resume using the device. _RST method is
> expected to stop DMA transfers and IRQs.
> 
> This patch introduces two functions as vfio_platform_acpi_has_reset and
> vfio_platform_acpi_call_reset. The has reset method is used to declare
> reset capability via the ioctl flag VFIO_DEVICE_FLAGS_RESET. The call
> reset function is used to execute the _RST ACPI method.
> 
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
>  drivers/vfio/platform/vfio_platform_common.c | 52 +++++++++++++++++++++++++++-
>  1 file changed, 51 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index 03483c2..2d9c905 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -28,6 +28,8 @@
>  #define DRIVER_AUTHOR   "Antonios Motakis <a.motakis@virtualopensystems.com>"
>  #define DRIVER_DESC     "VFIO platform base module"
>  
> +#define VFIO_PLATFORM_IS_ACPI(vdev) ((vdev)->acpihid != NULL)
> +
>  static LIST_HEAD(reset_list);
>  static DEFINE_MUTEX(driver_lock);
>  
> @@ -77,13 +79,55 @@ static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
>  #endif
>  }
>  
> +static inline
> +int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
> +				  const char **extra_dbg)
> +{
> +#ifdef CONFIG_ACPI
> +	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> +	struct device *dev = vdev->device;
> +	acpi_handle handle = ACPI_HANDLE(dev);
> +	acpi_status acpi_ret;
> +
> +	acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, &buffer);
> +	if (ACPI_FAILURE(acpi_ret)) {
> +		if (extra_dbg)
> +			*extra_dbg = acpi_format_exception(acpi_ret);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +#else
> +	return -ENOENT;
> +#endif
> +}
> +
> +static inline
> +bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
> +{
> +#ifdef CONFIG_ACPI
> +	struct device *dev = vdev->device;
> +	acpi_handle handle = ACPI_HANDLE(dev);
> +
> +	return acpi_has_method(handle, "_RST");
> +#else
> +	return false;
> +#endif
> +}

What exactly is the rationale for making these inline?  Clearly reset
is not a performance relevant path.  Thanks,

Alex

> +
>  static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
>  {
> +	if (VFIO_PLATFORM_IS_ACPI(vdev))
> +		return vfio_platform_acpi_has_reset(vdev);
> +
>  	return vdev->of_reset ? true : false;
>  }
>  
>  static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
>  {
> +	if (VFIO_PLATFORM_IS_ACPI(vdev))
> +		return;
> +
>  	vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
>  						    &vdev->reset_module);
>  	if (!vdev->of_reset) {
> @@ -95,6 +139,9 @@ static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
>  
>  static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
>  {
> +	if (VFIO_PLATFORM_IS_ACPI(vdev))
> +		return;
> +
>  	if (vdev->of_reset)
>  		module_put(vdev->reset_module);
>  }
> @@ -170,7 +217,10 @@ static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
>  static int vfio_platform_call_reset(struct vfio_platform_device *vdev,
>  				    const char **extra_dbg)
>  {
> -	if (vdev->of_reset) {
> +	if (VFIO_PLATFORM_IS_ACPI(vdev)) {
> +		dev_info(vdev->device, "reset\n");
> +		return vfio_platform_acpi_call_reset(vdev, extra_dbg);
> +	} else if (vdev->of_reset) {
>  		dev_info(vdev->device, "reset\n");
>  		return vdev->of_reset(vdev);
>  	}

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#1444711

On 7/14/2016 6:04 PM, Alex Williamson wrote:
>> +static inline
>> > +bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
>> > +{
>> > +#ifdef CONFIG_ACPI
>> > +	struct device *dev = vdev->device;
>> > +	acpi_handle handle = ACPI_HANDLE(dev);
>> > +
>> > +	return acpi_has_method(handle, "_RST");
>> > +#else
>> > +	return false;
>> > +#endif
>> > +}
> What exactly is the rationale for making these inline?  Clearly reset
> is not a performance relevant path.  Thanks,
> 
> Alex
> 

It is remaining from the previous stub functions which were inline. I'll get rid
of the inlines.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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