Hi Geert,
On 05/28/2018 05:26 PM, Geert Uytterhoeven wrote:
> If a device is part of a PM Domain (e.g. power and/or clock domain), its
> power state is managed using Runtime PM. Without Runtime PM, the device
> may not be powered up or clocked, causing subtle failures, crashes, or
> system lock-ups when the device is accessed by the guest.
>
> Fix this by adding Runtime PM support, powering the device when the VFIO
> device is opened by the guest.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> Reviewed-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> ---
> v3:
> - Drop controversial note about unsafeness of exporting fine-grained
> power management from host to guest,
thanks ;-)
>
> v2:
> - Improve wording,
> - Add Reviewed-by.
> ---
> drivers/vfio/platform/vfio_platform_common.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index b60bb5326668498c..41f862f055054543 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -17,6 +17,7 @@
> #include <linux/iommu.h>
> #include <linux/module.h>
> #include <linux/mutex.h>
> +#include <linux/pm_runtime.h>
> #include <linux/slab.h>
> #include <linux/types.h>
> #include <linux/uaccess.h>
> @@ -233,6 +234,8 @@ static void vfio_platform_release(void *device_data)
> const char *extra_dbg = NULL;
> int ret;
>
> + pm_runtime_put(vdev->device);
> +
> ret = vfio_platform_call_reset(vdev, &extra_dbg);
While reading the code again, the reset is using the HW. Don't you want
to call the get() before.
Thanks
Eric
> if (ret && vdev->reset_required) {
> dev_warn(vdev->device, "reset driver is required and reset call failed in release (%d) %s\n",
> @@ -275,6 +278,10 @@ static int vfio_platform_open(void *device_data)
> ret, extra_dbg ? extra_dbg : "");
> goto err_rst;
> }
> +
> + ret = pm_runtime_get_sync(vdev->device);
> + if (ret < 0)
> + goto err_rst;
> }
>
> vdev->refcnt++;
> @@ -690,6 +697,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>
> mutex_init(&vdev->igate);
>
> + pm_runtime_enable(vdev->device);
> return 0;
>
> put_iommu:
> @@ -707,6 +715,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
> vdev = vfio_del_group_dev(dev);
>
> if (vdev) {
> + pm_runtime_disable(vdev->device);
> vfio_platform_put_reset(vdev);
> vfio_iommu_group_put(dev->iommu_group, dev);
> }
>
