linux-kernel - Re: [PATCH V8 44/44] devdax: Enable stray access protection

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Date:   Fri, 4 Feb 2022 13:12:35 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     "Weiny, Ira" <ira.weiny@...el.com>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V8 44/44] devdax: Enable stray access protection

On Thu, Jan 27, 2022 at 9:55 AM <ira.weiny@...el.com> wrote:
>
> From: Ira Weiny <ira.weiny@...el.com>
>
> Device dax is primarily accessed through user space and kernel access is
> controlled through the kmap interfaces.
>
> Now that all valid kernel initiated access to dax devices have been
> accounted for, turn on PGMAP_PKEYS_PROTECT for device dax.
>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
>
> ---
> Changes for V8
>         Rebase to 5.17-rc1
>         Use pgmap_protection_available()
>         s/PGMAP_PKEYS_PROTECT/PGMAP_PROTECTION/
> ---
>  drivers/dax/device.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index d33a0613ed0c..cee375ef2cac 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -452,6 +452,8 @@ int dev_dax_probe(struct dev_dax *dev_dax)
>         if (dev_dax->align > PAGE_SIZE)
>                 pgmap->vmemmap_shift =
>                         order_base_2(dev_dax->align >> PAGE_SHIFT);
> +       if (pgmap_protection_available())
> +               pgmap->flags |= PGMAP_PROTECTION;

Looks good.

Reviewed-by: Dan Williams <dan.j.williams@...el.com>