netdev - Re: [PATCH V1 mlx5-next 07/13] vfio: Add 'invalid' state definitions

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Message-ID: <20211015103815.4b165d43.alex.williamson@redhat.com>
Date:   Fri, 15 Oct 2021 10:38:15 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Yishai Hadas <yishaih@...dia.com>
Cc:     <bhelgaas@...gle.com>, <jgg@...dia.com>, <saeedm@...dia.com>,
        <linux-pci@...r.kernel.org>, <kvm@...r.kernel.org>,
        <netdev@...r.kernel.org>, <kuba@...nel.org>, <leonro@...dia.com>,
        <kwankhede@...dia.com>, <mgurtovoy@...dia.com>, <maorg@...dia.com>
Subject: Re: [PATCH V1 mlx5-next 07/13] vfio: Add 'invalid' state
 definitions

On Wed, 13 Oct 2021 12:47:01 +0300
Yishai Hadas <yishaih@...dia.com> wrote:

> Add 'invalid' state definition to be used by drivers to set/check
> invalid state.
> 
> In addition dropped the non complied macro VFIO_DEVICE_STATE_SET_ERROR
> (i.e SATE instead of STATE) which seems unusable.

s/non complied/non-compiled/

We can certainly assume it's unused based on the typo, but removing it
or fixing it should be a separate patch.

> Fixes: a8a24f3f6e38 ("vfio: UAPI for migration interface for device state")
> Signed-off-by: Yishai Hadas <yishaih@...dia.com>
> Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> ---
>  include/linux/vfio.h      | 5 +++++
>  include/uapi/linux/vfio.h | 4 +---
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index b53a9557884a..6a8cf6637333 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -252,4 +252,9 @@ extern int vfio_virqfd_enable(void *opaque,
>  			      void *data, struct virqfd **pvirqfd, int fd);
>  extern void vfio_virqfd_disable(struct virqfd **pvirqfd);
>  
> +static inline bool vfio_is_state_invalid(u32 state)
> +{
> +	return state >= VFIO_DEVICE_STATE_INVALID;
> +}


Redundant, we already have !VFIO_DEVICE_STATE_VALID(state)

> +
>  #endif /* VFIO_H */
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index ef33ea002b0b..7f8fdada5eb3 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -609,6 +609,7 @@ struct vfio_device_migration_info {
>  #define VFIO_DEVICE_STATE_RUNNING   (1 << 0)
>  #define VFIO_DEVICE_STATE_SAVING    (1 << 1)
>  #define VFIO_DEVICE_STATE_RESUMING  (1 << 2)
> +#define VFIO_DEVICE_STATE_INVALID   (VFIO_DEVICE_STATE_RESUMING + 1)

Nak, device_state is not an enum, this is only one of the states we
currently define as invalid and usage such as the inline above ignores
the device state mask below, which induces future limits on how we can
expand the device_state field.  Thanks,

Alex

>  #define VFIO_DEVICE_STATE_MASK      (VFIO_DEVICE_STATE_RUNNING | \
>  				     VFIO_DEVICE_STATE_SAVING |  \
>  				     VFIO_DEVICE_STATE_RESUMING)
> @@ -621,9 +622,6 @@ struct vfio_device_migration_info {
>  	((state & VFIO_DEVICE_STATE_MASK) == (VFIO_DEVICE_STATE_SAVING | \
>  					      VFIO_DEVICE_STATE_RESUMING))
>  
> -#define VFIO_DEVICE_STATE_SET_ERROR(state) \
> -	((state & ~VFIO_DEVICE_STATE_MASK) | VFIO_DEVICE_SATE_SAVING | \
> -					     VFIO_DEVICE_STATE_RESUMING)
>  
>  	__u32 reserved;
>  	__u64 pending_bytes;