385ecfdfb5
This patch adds the following new device features for the low power entry and exit in the header file. The implementation for the same will be added in the subsequent patches. - VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY - VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY_WITH_WAKEUP - VFIO_DEVICE_FEATURE_LOW_POWER_EXIT For vfio-pci based devices, with the standard PCI PM registers, all power states cannot be achieved. The platform-based power management needs to be involved to go into the lowest power state. For doing low power entry and exit with platform-based power management, these device features can be used. The entry device feature has two variants. These two variants are mainly to support the different behaviour for the low power entry. If there is any access for the VFIO device on the host side, then the device will be moved out of the low power state without the user's guest driver involvement. Some devices (for example NVIDIA VGA or 3D controller) require the user's guest driver involvement for each low-power entry. In the first variant, the host can return the device to low power automatically. The device will continue to attempt to reach low power until the low power exit feature is called. In the second variant, if the device exits low power due to an access, the host kernel will signal the user via the provided eventfd and will not return the device to low power without a subsequent call to one of the low power entry features. A call to the low power exit feature is optional if the user provided eventfd is signaled. These device features only support VFIO_DEVICE_FEATURE_SET and VFIO_DEVICE_FEATURE_PROBE operations. Signed-off-by: Abhishek Sahu <abhsahu@nvidia.com> Link: https://lore.kernel.org/r/20220829114850.4341-2-abhsahu@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com> |
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| linux | ||
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| Kbuild | ||