From: Dave Hansen <dave@sr71.net>
To: linux-kernel@vger.kernel.org
Cc: bp@alien8.de, x86@kernel.org, hpa@zytor.com
Subject: Re: [RFC][PATCH 1/3] x86: introduce disabled-features
Date: Fri, 20 Jun 2014 13:40:12 -0700 [thread overview]
Message-ID: <53A49C2C.6030303@sr71.net> (raw)
In-Reply-To: <20140620161736.D6AC16FD@viggo.jf.intel.com>
On 06/20/2014 09:17 AM, Dave Hansen wrote:
> +/* These features, although they might be available in a CPU
> + * will not be used because the compile options to support
> + * them are not present.
> + *
> + * This code allows them to be checked and disabled at
> + * compile time withut an explicit #ifdef. Simply call
> + * cpu_has() or this_cpu_has().
> + * */
> +
> +#ifdef CONFIG_X86_INTEL_MPX
> +# define HAVE_MPX (1<<(X86_FEATURE_MPX & 31))
> +#else
> +# define HAVE_MPX 0
> +#endif
Urg. arch/x86/kvm/vmx.c has:
if (boot_cpu_has(X86_FEATURE_MPX))
rdmsrl(MSR_IA32_BNDCFGS, vmx->host_state.msr_host_...
And in that case we really _do_ want to test the actual CPU bit, despite
how we've configured MPX in the host kernel. We can call test_cpu_cap()
directly, I guess. But, all these interfaces are getting confusing. :(
prev parent reply other threads:[~2014-06-20 20:40 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-20 16:17 [RFC][PATCH 1/3] x86: introduce disabled-features Dave Hansen
2014-06-20 16:17 ` [RFC][PATCH 2/3] x86: add more disabled features Dave Hansen
2014-06-20 16:17 ` [RFC][PATCH 3/3] x86: make MP a required-feature on 64-bit Dave Hansen
2014-06-20 16:23 ` H. Peter Anvin
2014-06-20 16:30 ` Dave Hansen
2014-06-20 16:37 ` H. Peter Anvin
2014-06-20 17:43 ` Borislav Petkov
2014-06-20 17:47 ` H. Peter Anvin
2014-06-20 18:05 ` Borislav Petkov
2014-06-20 18:16 ` Dave Jones
2014-06-20 18:48 ` Borislav Petkov
2014-06-20 18:54 ` H. Peter Anvin
2014-06-20 20:00 ` Borislav Petkov
2014-06-20 20:22 ` H. Peter Anvin
2014-06-20 20:35 ` Borislav Petkov
2014-06-20 17:50 ` H. Peter Anvin
2014-06-20 18:15 ` Borislav Petkov
2014-06-20 18:57 ` H. Peter Anvin
2014-06-20 20:37 ` Borislav Petkov
2014-06-23 6:11 ` Andi Kleen
2014-06-20 16:20 ` [RFC][PATCH 1/3] x86: introduce disabled-features H. Peter Anvin
2014-06-20 17:20 ` Dave Hansen
2014-06-20 20:40 ` Dave Hansen [this message]
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