From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: David Woodhouse <dwmw@amazon.co.uk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 5/5] x86/pti: Do not enable PTI on fixed Intel processors
Date: Tue, 23 Jan 2018 18:45:19 +0000 [thread overview]
Message-ID: <20180123173312.1d8cf02f@alans-desktop> (raw)
In-Reply-To: <1516726375-25168-6-git-send-email-dwmw@amazon.co.uk>
On Tue, 23 Jan 2018 16:52:55 +0000
David Woodhouse <dwmw@amazon.co.uk> wrote:
> When they advertise the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO
> bit set, they don't need KPTI either.
This is starting to get messy because we will eventually need to integrate
AMD processors - no meltdown but spectre
VIA processors - probably no vulnerabilities at
least on the old ones
Intel with ND set - No meltdown
Anybody with no speculation - No meltdown, no spectre, no id bit
and it expands a lot with all sorts of 32bit processors. Would it make
more sense to make it table driven or do we want a separate function so
we can do:
if (!in_order_cpu()) {
}
around the whole lot ? I'm guessing the latter makes sense then
somethhing like this patch I'm running on my old atom widgets in 64bit
mode
static __initdata struct x86_cpu_id cpu_in_order[] = {
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CEDARVIEW, X86_FEATURE_ANY },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CLOVERVIEW, X86_FEATURE_ANY },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_LINCROFT, X86_FEATURE_ANY },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PENWELL, X86_FEATURE_ANY },
{ X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PINEVIEW, X86_FEATURE_ANY },
{}
};
static int in_order_cpu(void)
{
/* Processors with CPU id etc */
if (x86_match_cpu(cpu_in_order))
return 1;
/* Other rules here */
return 0;
}
Alan
next prev parent reply other threads:[~2018-01-23 18:45 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 16:52 [PATCH v2 0/5] Basic Speculation Control feature support David Woodhouse
2018-01-23 16:52 ` [PATCH v2 1/5] x86/cpufeatures: Add CPUID_7_EDX CPUID leaf David Woodhouse
2018-01-23 16:52 ` [PATCH v2 2/5] x86/cpufeatures: Add Intel feature bits for Speculation Control David Woodhouse
2018-01-23 18:43 ` Dave Hansen
2018-01-24 1:23 ` Woodhouse, David
2018-01-24 1:28 ` Dave Hansen
2018-01-24 8:13 ` Woodhouse, David
2018-01-23 16:52 ` [PATCH v2 3/5] x86/cpufeatures: Add AMD " David Woodhouse
2018-01-24 8:39 ` Kirill A. Shutemov
2018-01-24 8:40 ` David Woodhouse
2018-01-23 16:52 ` [PATCH v2 4/5] x86/msr: Add definitions for new speculation control MSRs David Woodhouse
2018-01-23 18:27 ` Dave Hansen
2018-01-23 18:31 ` Greg KH
2018-01-23 18:48 ` Woodhouse, David
2018-01-23 16:52 ` [PATCH v2 5/5] x86/pti: Do not enable PTI on fixed Intel processors David Woodhouse
2018-01-23 18:12 ` Andi Kleen
2018-01-24 1:21 ` David Woodhouse
2018-01-23 18:40 ` Dave Hansen
2018-01-24 1:27 ` David Woodhouse
2018-01-23 18:41 ` Dave Hansen
2018-01-23 18:44 ` Woodhouse, David
2018-01-23 18:45 ` Alan Cox [this message]
2018-01-23 19:02 ` Andrew Cooper
2018-01-23 20:45 ` Alan Cox
2018-01-23 20:38 ` Linus Torvalds
2018-01-23 20:50 ` David Woodhouse
2018-01-24 16:25 ` David Woodhouse
2018-01-24 17:07 ` Alan Cox
2018-01-24 17:42 ` David Woodhouse
2018-01-24 18:40 ` Alan Cox
2018-01-24 18:59 ` David Woodhouse
2018-01-24 19:37 ` David Woodhouse
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