From: Andi Kleen <ak@linux.intel.com>
To: David Woodhouse <dwmw@amazon.co.uk>
Cc: arjan@linux.intel.com, tglx@linutronix.de, 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, torvalds@linux-foundation.org,
gregkh@linux-foundation.org, thomas.lendacky@amd.com
Subject: Re: [PATCH v2 5/5] x86/pti: Do not enable PTI on fixed Intel processors
Date: Tue, 23 Jan 2018 10:12:01 -0800 [thread overview]
Message-ID: <20180123181201.GO7844@tassilo.jf.intel.com> (raw)
In-Reply-To: <1516726375-25168-6-git-send-email-dwmw@amazon.co.uk>
>
> - if (c->x86_vendor != X86_VENDOR_AMD)
> - setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
> + if (c->x86_vendor != X86_VENDOR_AMD) {
> + u64 ia32_cap = 0;
> +
> + if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
> + rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
> + if (!(ia32_cap & ARCH_CAP_RDCL_NO))
> + setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
This means that in a hypervisor which passes through the CPUID,
but actually doesn't implement the MSR (so rdmsr #GPs and returns 0)
it would be cleared.
It would be better to usr rdmsrl_safe and check the return value.
-Andi
next prev parent reply other threads:[~2018-01-23 18:12 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 [this message]
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
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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