On Thu, Nov 12, 2020 at 10:12:01AM +1100, Anand K. Mistry wrote:
> 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.
You didn't have to get the email, but I would assume that you at least
tested the backport if you asked for it to happen, right? :)
thanks,
greg k-h
