From 705b004ee377b789e39ae237519bab714297ac83 Mon Sep 17 00:00:00 2001 From: Yi Liu Date: Thu, 20 Apr 2023 22:36:11 -0700 Subject: docs: kvm: vfio: Suggest KVM_DEV_VFIO_GROUP_ADD vs VFIO_GROUP_GET_DEVICE_FD ordering as some vfio_device's open_device op requires kvm pointer and kvm pointer set is part of GROUP_ADD. Reviewed-by: Kevin Tian Signed-off-by: Yi Liu Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20230421053611.55839-1-yi.l.liu@intel.com Signed-off-by: Alex Williamson --- Documentation/virt/kvm/devices/vfio.rst | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation/virt') diff --git a/Documentation/virt/kvm/devices/vfio.rst b/Documentation/virt/kvm/devices/vfio.rst index 2d20dc561069..08b544212638 100644 --- a/Documentation/virt/kvm/devices/vfio.rst +++ b/Documentation/virt/kvm/devices/vfio.rst @@ -39,3 +39,8 @@ KVM_DEV_VFIO_GROUP attributes: - @groupfd is a file descriptor for a VFIO group; - @tablefd is a file descriptor for a TCE table allocated via KVM_CREATE_SPAPR_TCE. + +The GROUP_ADD operation above should be invoked prior to accessing the +device file descriptor via VFIO_GROUP_GET_DEVICE_FD in order to support +drivers which require a kvm pointer to be set in their .open_device() +callback. -- cgit v1.2.3