From: Thomas Gleixner <tglx@linutronix.de>
To: David Woodhouse <dwmw@amazon.co.uk>
Cc: arjan@linux.intel.com, karahmed@amazon.de, x86@kernel.org,
linux-kernel@vger.kernel.org, tim.c.chen@linux.intel.com,
bp@alien8.de, peterz@infradead.org, pbonzini@redhat.com,
ak@linux.intel.com, torvalds@linux-foundation.org,
gregkh@linux-foundation.org
Subject: Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel
Date: Tue, 30 Jan 2018 11:37:49 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1801301136590.1797@nanos> (raw)
In-Reply-To: <1517269773-16750-1-git-send-email-dwmw@amazon.co.uk>
On Mon, 29 Jan 2018, David Woodhouse wrote:
> Despite the fact that all the other code there seems to be doing it,
> just using set_cpu_cap() in early_intel_init() doesn't actually work.
>
> When the CPU is queried again in identify_boot_cpu(), it all gets
> overwritten again. Do it in init_scattered_cpuid_features() instead.
>
> Turning the bits off for bad microcode can use setup_clear_cpu_cap()
> to force them off for all CPUs; I was less keen on forcing the feature
> bits *on* that way.
>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> Fixes: 2961298e ("x86/cpufeatures: Clean up Spectre v2 related CPUID flags")
> ---
> I feel I must be missing something. Is the rest of early_init_intel() broken too?
A lot of that stuff is duct taped and works more by chance than by
design. Borislav is looking into cleaning that up already.
Thanks,
tglx
next prev parent reply other threads:[~2018-01-30 10:37 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-29 23:49 David Woodhouse
2018-01-30 10:37 ` Thomas Gleixner [this message]
2018-01-30 10:58 ` Borislav Petkov
2018-01-30 11:03 ` David Woodhouse
2018-01-30 11:18 ` Borislav Petkov
2018-01-30 11:28 ` David Woodhouse
2018-01-30 11:37 ` Thomas Gleixner
2018-01-30 12:09 ` David Woodhouse
2018-01-30 12:57 ` Thomas Gleixner
2018-01-30 13:11 ` Borislav Petkov
2018-01-30 14:01 ` Arjan van de Ven
2018-01-30 14:54 ` Alan Cox
2018-01-30 14:57 ` David Woodhouse
2018-01-30 18:19 ` Henrique de Moraes Holschuh
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