linux-kernel - Re: [v4.17-rcx] Lost IBPB, IBRS_FW support for spectre

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Date:   Tue, 1 May 2018 14:59:39 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Jörg Otte <jrg.otte@...il.com>
cc:     kirill.shutemov@...ux.intel.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [v4.17-rcx] Lost IBPB, IBRS_FW support for spectre_v2
 mitigation.

On Tue, 1 May 2018, Jörg Otte wrote:
> 2018-04-30 21:53 GMT+02:00 Thomas Gleixner <tglx@...utronix.de>:
> > --- a/arch/x86/kernel/cpu/common.c
> > +++ b/arch/x86/kernel/cpu/common.c
> > @@ -848,6 +848,11 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
> >                 c->x86_power = edx;
> >         }
> >
> > +       if (c->extended_cpuid_level >= 0x80000008) {
> > +               cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
> > +               c->x86_capability[CPUID_8000_0008_EBX] = ebx;
> > +       }
> > +
> >         if (c->extended_cpuid_level >= 0x8000000a)
> >                 c->x86_capability[CPUID_8000_000A_EDX] = cpuid_edx(0x8000000a);
> >
> 
> No, does not fix it.

Then I really have no idea how reverting the patch you pointed out would
fix it.

Thanks,

	tglx