[PATCH v3] docs: kvm: vfio: Suggest KVM_DEV_VFIO_GROUP_ADD vs VFIO_GROUP_GET_DEVICE_FD ordering

[PATCH v3] docs: kvm: vfio: Suggest KVM_DEV_VFIO_GROUP_ADD vs VFIO_GROUP_GET_DEVICE_FD ordering

[Yi Liu]

as some vfio_device's open_device op requires kvm pointer and kvm pointer
set is part of GROUP_ADD.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
v3:
 - Add r-b from Kevin
 - Remove "::" to fix "WARNING: Literal block expected; none found."
   "make htmldocs" looks good.
 - Rename the subject per Alex's suggestion

v2: https://lore.kernel.org/kvm/20230222022231.266381-1-yi.l.liu@intel.com/
 - Adopt Alex's suggestion

v1: https://lore.kernel.org/kvm/20230221034114.135386-1-yi.l.liu@intel.com/
---
 Documentation/virt/kvm/devices/vfio.rst | 5 +++++
 1 file changed, 5 insertions(+)

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.
-- 
2.34.1

Re: [PATCH v3] docs: kvm: vfio: Suggest KVM_DEV_VFIO_GROUP_ADD vs VFIO_GROUP_GET_DEVICE_FD ordering

[Jason Gunthorpe]

On Thu, Apr 20, 2023 at 10:36:11PM -0700, Yi Liu wrote:
> as some vfio_device's open_device op requires kvm pointer and kvm pointer
> set is part of GROUP_ADD.
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> v3:
>  - Add r-b from Kevin
>  - Remove "::" to fix "WARNING: Literal block expected; none found."
>    "make htmldocs" looks good.
>  - Rename the subject per Alex's suggestion
> 
> v2: https://lore.kernel.org/kvm/20230222022231.266381-1-yi.l.liu@intel.com/
>  - Adopt Alex's suggestion
> 
> v1: https://lore.kernel.org/kvm/20230221034114.135386-1-yi.l.liu@intel.com/
> ---
>  Documentation/virt/kvm/devices/vfio.rst | 5 +++++
>  1 file changed, 5 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason

Re: [PATCH v3] docs: kvm: vfio: Suggest KVM_DEV_VFIO_GROUP_ADD vs VFIO_GROUP_GET_DEVICE_FD ordering

[Alex Williamson]

On Thu, 20 Apr 2023 22:36:11 -0700
Yi Liu <yi.l.liu@intel.com> wrote:

> as some vfio_device's open_device op requires kvm pointer and kvm pointer
> set is part of GROUP_ADD.
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> v3:
>  - Add r-b from Kevin
>  - Remove "::" to fix "WARNING: Literal block expected; none found."
>    "make htmldocs" looks good.
>  - Rename the subject per Alex's suggestion
> 
> v2: https://lore.kernel.org/kvm/20230222022231.266381-1-yi.l.liu@intel.com/
>  - Adopt Alex's suggestion
> 
> v1: https://lore.kernel.org/kvm/20230221034114.135386-1-yi.l.liu@intel.com/
> ---
>  Documentation/virt/kvm/devices/vfio.rst | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> 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.

Applied to vfio next branch for v6.4.  Thanks,

Alex