Messages in this thread | | | Date | Fri, 15 Jul 2022 10:21:13 -0700 | From | Pawan Gupta <> | Subject | Re: [PATCH v2] x86/bugs: Warn when "ibrs" mitigation is selected on Enhanced IBRS parts |
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On Fri, Jul 15, 2022 at 07:25:43AM +0200, Greg KH wrote: > On Thu, Jul 14, 2022 at 04:15:35PM -0700, Pawan Gupta wrote: > > IBRS mitigation for spectre_v2 forces write to MSR_IA32_SPEC_CTRL at > > every kernel entry/exit. On Enhanced IBRS parts setting > > MSR_IA32_SPEC_CTRL[IBRS] only once at boot is sufficient. MSR writes at > > every kernel entry/exit incur unnecessary performance loss. > > > > When Enhanced IBRS feature is present, print a warning about this > > unnecessary performance loss. > > > > Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> > > --- > > v1->v2: Instead of changing the mitigation, print a warning about the > > perf loss. > > > > v1: https://lore.kernel.org/lkml/0456b35fb9ef957d9a9138e0913fb1a3fd445dff.1657747493.git.pawan.kumar.gupta@linux.intel.com/ > > > > arch/x86/kernel/cpu/bugs.c | 3 +++ > > 1 file changed, 3 insertions(+) > > <formletter> > > This is not the correct way to submit patches for inclusion in the > stable kernel tree. Please read: > https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html > for how to do this properly. > > </formletter>
Sorry, I CCed stable@ by mistake. This version just adds a warning, it is not intended to be backported.
Thanks, Pawan
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