From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B857C433EF for ; Thu, 10 Feb 2022 18:57:41 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B907849F48; Thu, 10 Feb 2022 13:57:40 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yQcJMvrC4J8t; Thu, 10 Feb 2022 13:57:38 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C20B849F0C; Thu, 10 Feb 2022 13:57:38 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D01E249F09 for ; Thu, 10 Feb 2022 13:57:37 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id WSz0nRhq440u for ; Thu, 10 Feb 2022 13:57:36 -0500 (EST) Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 6ACCF412FC for ; Thu, 10 Feb 2022 13:57:36 -0500 (EST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id AC3CAB8271F; Thu, 10 Feb 2022 18:57:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D286C004E1; Thu, 10 Feb 2022 18:57:30 +0000 (UTC) Date: Thu, 10 Feb 2022 18:57:26 +0000 From: Catalin Marinas To: Mark Brown Subject: Re: [PATCH v11 08/40] arm64/sme: Manually encode SME instructions Message-ID: References: <20220207152109.197566-1-broonie@kernel.org> <20220207152109.197566-9-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220207152109.197566-9-broonie@kernel.org> Cc: Basant Kumar Dwivedi , Will Deacon , Luis Machado , Szabolcs Nagy , Marc Zyngier , Shuah Khan , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, Alan Hayward , Shuah Khan , kvmarm@lists.cs.columbia.edu, Salil Akerkar X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Mon, Feb 07, 2022 at 03:20:37PM +0000, Mark Brown wrote: > As with SVE rather than impose ambitious toolchain requirements for SME > we manually encode the few instructions which we require in order to > perform the work the kernel needs to do. The instructions used to save > and restore context are provided as assembler macros while those for > entering and leaving streaming mode are done in asm volatile blocks > since they are expected to be used from C. > > We could do the SMSTART and SMSTOP operations with read/modify/write > cycles on SVCR but using the aliases provided for individual field > accesses should be slightly faster. These instructions are aliases for > MSR but since our minimum toolchain requirements are old enough to mean > that we can't use the sX_X_cX_cX_X form and they always use xzr rather > than taking a value like write_sysreg_s() wants we just use .inst. > > Signed-off-by: Mark Brown > --- > arch/arm64/include/asm/fpsimd.h | 25 +++++++++++++ > arch/arm64/include/asm/fpsimdmacros.h | 53 +++++++++++++++++++++++++++ > 2 files changed, 78 insertions(+) > > diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h > index cb24385e3632..c90f7f99a768 100644 > --- a/arch/arm64/include/asm/fpsimd.h > +++ b/arch/arm64/include/asm/fpsimd.h > @@ -249,6 +249,31 @@ static inline void sve_setup(void) { } > > #endif /* ! CONFIG_ARM64_SVE */ > > +#ifdef CONFIG_ARM64_SME > + > +static inline void sme_smstart_sm(void) > +{ > + asm volatile(".inst 0xd503437f"); > +} > + > +static inline void sme_smstop_sm(void) > +{ > + asm volatile(".inst 0xd503427f"); > +} > + > +static inline void sme_smstop(void) > +{ > + asm volatile(".inst 0xd503467f"); > +} I think you can use xzr with __msr_s. It would be more consistent if we had some sysregs defined to be used with __msr_s. -- Catalin _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm