On Thu, 12 Nov 2020 at 17:15, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> 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? :)
The conflict was so trivial (a single newline in a comment) I didn't
really think about it. And yes, the patch is well tested against 5.4
(which is my target kernel), and 4.14.
