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. Note that while more fine-grained power management could be implemented on the guest side, if exported by the host, this would be inherently unsafe, as abusing it may take down the whole system. Signed-off-by: Geert Uytterhoeven <[email protected]> Reviewed-by: Simon Horman <[email protected]> --- 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); 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); } -- 2.7.4
