Re: [PATCH] virtio_blk: add VIRTIO_BLK_F_LIFETIME feature support

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Alvaro Karsz <alvaro.karsz@solid-run.com>
Cc: Jens Axboe <axboe@kernel.dk>, Paolo Bonzini <pbonzini@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	virtualization@lists.linux-foundation.org
Subject: Re: [PATCH] virtio_blk: add VIRTIO_BLK_F_LIFETIME feature support
Date: Fri, 11 Nov 2022 09:17:00 -0500	[thread overview]
Message-ID: <20221111091556-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CAJs=3_AvDxkY-DZCbRUPw08DsHCoNS6s7cCjcjXMiFkq1K-03w@mail.gmail.com>

On Fri, Nov 11, 2022 at 02:20:01PM +0200, Alvaro Karsz wrote:
> > +       /* The virtio_blk_lifetime struct fields follow virtio spec.
> > +        * There is no check/decode on values received from the device.
> > +        * The data is sent as is to the user.
> > +        */
> 
> After more thought, I think that the driver should handle the
> virtio_blk_lifetime struct endianness.
> Something like:
> ...
> lifetime.pre_eol_info = __le16_to_cpu(lifetime.pre_eol_info);
> lifetime. device_lifetime_est_typ_a  = __le16_to_cpu(lifetime.
> device_lifetime_est_typ_a);
> lifetime. device_lifetime_est_typ_b  = __le16_to_cpu(lifetime.
> device_lifetime_est_typ_b);
> 
> if (copy_to_user((void __user *)arg, (void *)&lifetime,
> ...
> 
> What do you think?

I think if you are going to pass struct virtio_blk_lifetime to
userspace, better pass it as defined in the spec, in LE format.

> I'll wait a few days and create a new version.

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