Messages in this thread | | | From | KP Singh <> | Date | Tue, 21 Feb 2023 11:35:29 -0800 | Subject | Re: [PATCH v2 1/2] x86/speculation: Allow enabling STIBP with legacy IBRS |
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On Tue, Feb 21, 2023 at 11:29 AM Greg KH <gregkh@linuxfoundation.org> wrote: > > On Tue, Feb 21, 2023 at 07:49:07PM +0100, KP Singh wrote: > > Setting the IBRS bit implicitly enables STIBP to protect against > > cross-thread branch target injection. With enhanced IBRS, the bit it set > > once and is not cleared again. However, on CPUs with just legacy IBRS, > > IBRS bit set on user -> kernel and cleared on kernel -> user (a.k.a > > KERNEL_IBRS). Clearing this bit also disables the implicitly enabled > > STIBP, thus requiring some form of cross-thread protection in userspace. > > > > Enable STIBP, either opt-in via prctl or seccomp, or always on depending > > on the choice of mitigation selected via spectre_v2_user. > > > > Reported-by: José Oliveira <joseloliveira11@gmail.com> > > Reported-by: Rodrigo Branco <rodrigo@kernelhacking.com> > > Reviewed-by: Alexandra Sandulescu <aesa@google.com> > > Fixes: 7c693f54c873 ("x86/speculation: Add spectre_v2=ibrs option to support Kernel IBRS") > > Cc: stable@vger.kernel.org > > Signed-off-by: KP Singh <kpsingh@kernel.org> > > --- > > arch/x86/kernel/cpu/bugs.c | 33 ++++++++++++++++++++++----------- > > 1 file changed, 22 insertions(+), 11 deletions(-) > > Why isn't patch 2/2 for stable as well?
It should be. I actually forgot to remove stable from the first one as there are still ongoing discussions and people kept having to "drop stable". I can send a v3 with stable Cc'ed. Should it have a fixes tag too?
> > thanks, > > greg k-h
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