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 X-Spam-Level: X-Spam-Status: No, score=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88727C433DB for ; Tue, 19 Jan 2021 11:35:59 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3890C221EA for ; Tue, 19 Jan 2021 11:35:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3890C221EA Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.70294.126108 (Exim 4.92) (envelope-from ) id 1l1pIY-0005dX-C2; Tue, 19 Jan 2021 11:35:46 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 70294.126108; Tue, 19 Jan 2021 11:35:46 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l1pIY-0005dQ-8L; Tue, 19 Jan 2021 11:35:46 +0000 Received: by outflank-mailman (input) for mailman id 70294; Tue, 19 Jan 2021 11:35:44 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l1pIW-0005dF-Np for xen-devel@lists.xenproject.org; Tue, 19 Jan 2021 11:35:44 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id ae755dea-bf1d-4db4-95e6-628b3c39ad6f; Tue, 19 Jan 2021 11:35:43 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D4E57AC8F; Tue, 19 Jan 2021 11:35:42 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: ae755dea-bf1d-4db4-95e6-628b3c39ad6f X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611056143; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=gpscQ+ry3D0aBJJjBo94VXE/FRCNtrHj+UvlHFS+Veo=; b=fbvIGIFuVPP6/ERbazeHt9dSawI1HjIaJUXDaFYFQtbA11bnw0Fp8vk0f+zmCxssgWaCGK Meu4jhUITOG3h7IIf5w9qlWzytxY6MvI+9nRbMQKye/is+UDb3GV/lPaea6S1y1Tz6ff1M nBvJ0mHX5Is85rzIfuxJ2OQ2PrDLE7M= Subject: Re: [PATCH v3 07/15] x86/alternative: support "not feature" and ALTERNATIVE_TERNARY To: Borislav Petkov Cc: xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" References: <20201217093133.1507-1-jgross@suse.com> <20201217093133.1507-8-jgross@suse.com> <20210107190819.GI14697@zn.tnic> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <5ed34a1d-86c4-ed03-4c92-b275a555c41c@suse.com> Date: Tue, 19 Jan 2021 12:35:42 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210107190819.GI14697@zn.tnic> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0uwsXwgjCC58khCi7aVmZVWQ3hQMuwUIh" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --0uwsXwgjCC58khCi7aVmZVWQ3hQMuwUIh Content-Type: multipart/mixed; boundary="2HZuOF5yMr7z4N1W9je7pKeX4DttW2NH2"; protected-headers="v1" From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= To: Borislav Petkov Cc: xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Message-ID: <5ed34a1d-86c4-ed03-4c92-b275a555c41c@suse.com> Subject: Re: [PATCH v3 07/15] x86/alternative: support "not feature" and ALTERNATIVE_TERNARY References: <20201217093133.1507-1-jgross@suse.com> <20201217093133.1507-8-jgross@suse.com> <20210107190819.GI14697@zn.tnic> In-Reply-To: <20210107190819.GI14697@zn.tnic> --2HZuOF5yMr7z4N1W9je7pKeX4DttW2NH2 Content-Type: multipart/mixed; boundary="------------A99D9741BE5A0D4DF4E23EDD" Content-Language: en-US This is a multi-part message in MIME format. --------------A99D9741BE5A0D4DF4E23EDD Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 07.01.21 20:08, Borislav Petkov wrote: > On Thu, Dec 17, 2020 at 10:31:25AM +0100, Juergen Gross wrote: >> Instead of only supporting to modify instructions when a specific >> feature is set, support doing so for the case a feature is not set. >> >> As today a feature is specified using a 16 bit quantity and the highes= t >> feature number in use is around 600, using a negated feature number fo= r >> specifying the inverted case seems to be appropriate. >> >> ALTERNATIVE "default_instr", "patched_instr", ~FEATURE_NR >> >> will start with "default_instr" and patch that with "patched_instr" in= >> case FEATURE_NR is not set. >> >> Using that add ALTERNATIVE_TERNARY: >> >> ALTERNATIVE_TERNARY "default_instr", FEATURE_NR, >> "feature_on_instr", "feature_off_instr" >> >> which will start with "default_instr" and at patch time will, dependin= g >> on FEATURE_NR being set or not, patch that with either >> "feature_on_instr" or "feature_off_instr". >=20 > How about an even simpler one (only build-tested): >=20 > --- > diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/= asm/alternative-asm.h > index 464034db299f..d52b423d3cab 100644 > --- a/arch/x86/include/asm/alternative-asm.h > +++ b/arch/x86/include/asm/alternative-asm.h > @@ -109,6 +109,9 @@ > .popsection > .endm > =20 > +#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr1, newinstr2) \= > + ALTERNATIVE_2 oldinstr, newinstr1, feature, newinstr2, X86_FEATURE_TE= RNARY > + > #endif /* __ASSEMBLY__ */ > =20 > #endif /* _ASM_X86_ALTERNATIVE_ASM_H */ > diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/= alternative.h > index 13adca37c99a..f170cbe89539 100644 > --- a/arch/x86/include/asm/alternative.h > +++ b/arch/x86/include/asm/alternative.h > @@ -175,6 +175,9 @@ static inline int alternatives_text_reserved(void *= start, void *end) > ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \ > ".popsection\n" > =20 > +#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr1, newinstr2) \= > + ALTERNATIVE_2(oldinstr, newinstr1, feature, newinstr2, X86_FEATURE_TE= RNARY) > + > #define ALTERNATIVE_3(oldinsn, newinsn1, feat1, newinsn2, feat2, newi= nsn3, feat3) \ > OLDINSTR_3(oldinsn, 1, 2, 3) \ > ".pushsection .altinstructions,\"a\"\n" \ > @@ -206,6 +209,9 @@ static inline int alternatives_text_reserved(void *= start, void *end) > #define alternative_2(oldinstr, newinstr1, feature1, newinstr2, featu= re2) \ > asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, new= instr2, feature2) ::: "memory") > =20 > +#define alternative_ternary(oldinstr, feature, newinstr1, newinstr2) \= > + asm_inline volatile(ALTERNATIVE_TERNARY(oldinstr, feature, newinstr1,= newinstr2) ::: "memory") > + > /* > * Alternative inline assembly with input. > * > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/= cpufeatures.h > index 84b887825f12..cc634db0b91f 100644 > --- a/arch/x86/include/asm/cpufeatures.h > +++ b/arch/x86/include/asm/cpufeatures.h > @@ -108,7 +108,7 @@ > #define X86_FEATURE_EXTD_APICID ( 3*32+26) /* Extended APICID (8 bit= s) */ > #define X86_FEATURE_AMD_DCM ( 3*32+27) /* AMD multi-node processor *= / > #define X86_FEATURE_APERFMPERF ( 3*32+28) /* P-State hardware coordi= nation feedback capability (APERF/MPERF MSRs) */ > -/* free ( 3*32+29) */ > +#define X86_FEATURE_TERNARY ( 3*32+29) /* "" Synthetic bit for ALTERN= ATIVE_TERNARY() */ In fact this should rather be named "X86_FEATURE_TRUE", as this is its semantics. And I think I can define it to the value 0xffff instead of using a "real" bit for it. 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