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,
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
