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From: Dave Hansen <dave.hansen@intel.com>
To: Jim Mattson <jmattson@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tony Luck <tony.luck@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Chang S. Bae" <chang.seok.bae@intel.com>,
	Juergen Gross <jgross@suse.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Babu Moger <babu.moger@amd.com>, Jing Liu <jing2.liu@intel.com>,
	Sean Christopherson <seanjc@google.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] x86/cpufeatures: Add macros for Intel's new fast rep string features
Date: Thu, 3 Feb 2022 12:25:43 -0800	[thread overview]
Message-ID: <e313b068-b5d6-dbc4-9894-02d759d2fe55@intel.com> (raw)
In-Reply-To: <20220203194308.2469117-2-jmattson@google.com>

On 2/3/22 11:43, Jim Mattson wrote:
> Even if no one else cares, these features should be exposed to kvm
> guests, and the code for the KVM_GET_SUPPORTED_CPUID ioctl is more
> readable if the bits have corresponding X86_FEATURE macros.

I went digging around KVM_GET_SUPPORTED_CPUID and didn't see any obvious
unreadable things resulting from not having these defines.  Maybe I'm
looking in the wrong spot.  Do you have a slightly more specific pointer?

> +#define X86_FEATURE_FZRM		(12*32+10) /* Fast zero-length REP MOVSB */
> +#define X86_FEATURE_FSRS		(12*32+11) /* Fast short REP STOSB */
> +#define X86_FEATURE_FSRC		(12*32+12) /* Fast short REP {CMPSB,SCASB} */

If the use really is for inside the kernel, maybe we should hide them
from cpuinfo:

#define X86_FEATURE_FSRC		(12*32+12) /* "" Fast short REP {CMPSB,SCASB} */


  reply	other threads:[~2022-02-03 20:25 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-03 19:43 [PATCH 1/2] x86/cpufeatures: Put the AMX macros in the word 18 block Jim Mattson
2022-02-03 19:43 ` [PATCH 2/2] x86/cpufeatures: Add macros for Intel's new fast rep string features Jim Mattson
2022-02-03 20:25   ` Dave Hansen [this message]
2022-02-03 20:50     ` Jim Mattson
2022-02-03 20:27 ` [tip: x86/cpu] x86/cpufeatures: Put the AMX macros in the word 18 block tip-bot2 for Jim Mattson
2022-02-08  9:54 ` tip-bot2 for Jim Mattson

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