On Wed, 11 Nov 2020 at 23:23, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Wed, Nov 11, 2020 at 11:09:13PM +1100, Anand K. Mistry wrote:
> > Hi,
> >
> > I'm requesting a stable merge for commit
> > 1978b3a53a74e3230cd46932b149c6e62e832e9a
> > ("x86/speculation: Allow IBPB to be conditionally enabled on CPUs with
> > always-on STIBP")
> > into the stable branch for 5.4. Note, the commit is already queued for
> > inclusion into the next 5.9 stable release
> > (https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/queue-5.9/x86-speculation-allow-ibpb-to-be-conditionally-enabl.patch).
> >
> > The patch fixes an issue where a Spectre-v2-user mitigation could not
> > be enabled via prctl() on certain AMD CPUs. The issue was introduced
> > in commit 21998a351512eba4ed5969006f0c55882d995ada
> > ("x86/speculation: Avoid force-disabling IBPB based on STIBP and
> > enhanced IBRS.")
> > which was merged into the 5.4 stable branch as commit
> > 6d60d5462a91eb46fb88b016508edfa8ee0bc7c8. This commit also exists in
> > 4.19, 4.14, 4.9, and 4.4, so those kernels are also likely affected by
> > this bug.
>
> As I asked when I sent out a "FAILED:" message for this patch, if
> someone wants it backported to older kernels, they will need to provide
> the backported versions of it, as the patch does not apply cleanly
> as-is.
>
> Can you please do that?
Oh, I didn't get that message. I'll prepare a backport.
>
> thanks,
>
> greg k-h
--
Anand K. Mistry
Software Engineer
Google Australia
