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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 9C704C2BBCD for ; Thu, 17 Dec 2020 09:34:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6485023975 for ; Thu, 17 Dec 2020 09:34:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727881AbgLQJdu (ORCPT ); Thu, 17 Dec 2020 04:33:50 -0500 Received: from mx2.suse.de ([195.135.220.15]:43676 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727334AbgLQJdV (ORCPT ); Thu, 17 Dec 2020 04:33:21 -0500 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=1608197508; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=f7wMr3rCKeUgxXFk8LrwUaFxcJhxPpDbM3TMdRt3vHc=; b=ZxRpHnPLouJGWl0qvClnnvw5rU/SYAMpP+qybw/K+Uy0fLrHnnu5ahxvF0cCDOZeqZlvyZ dlR9w0GMgGxy9KFsuKFvnomGmDS65MgZNHk5x24aIFmT/GaUidfJrqQXQlfvoGrGqb0z2i ENfyfKAHzdoZsjSKRBdvzoLmTj5g32g= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 6A6B5B71C; Thu, 17 Dec 2020 09:31:48 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" Subject: [PATCH v3 08/15] x86: add new features for paravirt patching Date: Thu, 17 Dec 2020 10:31:26 +0100 Message-Id: <20201217093133.1507-9-jgross@suse.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201217093133.1507-1-jgross@suse.com> References: <20201217093133.1507-1-jgross@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For being able to switch paravirt patching from special cased custom code sequences to ALTERNATIVE handling some X86_FEATURE_* are needed as new features. This enables to have the standard indirect pv call as the default code and to patch that with the non-Xen custom code sequence via ALTERNATIVE patching later. Make sure paravirt patching is performed before alternative patching. Signed-off-by: Juergen Gross --- V3: - add comment (Boris Petkov) - no negative features (Boris Petkov) --- arch/x86/include/asm/cpufeatures.h | 2 ++ arch/x86/kernel/alternative.c | 40 ++++++++++++++++++++++++++++-- 2 files changed, 40 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index f5ef2d5b9231..1077b675a008 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -237,6 +237,8 @@ #define X86_FEATURE_VMCALL ( 8*32+18) /* "" Hypervisor supports the VMCALL instruction */ #define X86_FEATURE_VMW_VMMCALL ( 8*32+19) /* "" VMware prefers VMMCALL hypercall instruction */ #define X86_FEATURE_SEV_ES ( 8*32+20) /* AMD Secure Encrypted Virtualization - Encrypted State */ +#define X86_FEATURE_PVUNLOCK ( 8*32+21) /* "" PV unlock function */ +#define X86_FEATURE_VCPUPREEMPT ( 8*32+22) /* "" PV vcpu_is_preempted function */ /* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */ #define X86_FEATURE_FSGSBASE ( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 0a904fb2678b..abb481808811 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -600,6 +600,15 @@ int alternatives_text_reserved(void *start, void *end) #endif /* CONFIG_SMP */ #ifdef CONFIG_PARAVIRT +static void __init paravirt_set_cap(void) +{ + if (!pv_is_native_spin_unlock()) + setup_force_cpu_cap(X86_FEATURE_PVUNLOCK); + + if (!pv_is_native_vcpu_is_preempted()) + setup_force_cpu_cap(X86_FEATURE_VCPUPREEMPT); +} + void __init_or_module apply_paravirt(struct paravirt_patch_site *start, struct paravirt_patch_site *end) { @@ -623,6 +632,8 @@ void __init_or_module apply_paravirt(struct paravirt_patch_site *start, } extern struct paravirt_patch_site __start_parainstructions[], __stop_parainstructions[]; +#else +static void __init paravirt_set_cap(void) { } #endif /* CONFIG_PARAVIRT */ /* @@ -730,6 +741,33 @@ void __init alternative_instructions(void) * patching. */ + /* + * Paravirt patching and alternative patching can be combined to + * replace a function call with a short direct code sequence (e.g. + * by setting a constant return value instead of doing that in an + * external function). + * In order to make this work the following sequence is required: + * 1. set (artificial) features depending on used paravirt + * functions which can later influence alternative patching + * 2. apply paravirt patching (generally replacing an indirect + * function call with a direct one) + * 3. apply alternative patching (e.g. replacing a direct function + * call with a custom code sequence) + * Doing paravirt patching after alternative patching would clobber + * the optimization of the custom code with a function call again. + */ + paravirt_set_cap(); + + /* + * First patch paravirt functions, such that we overwrite the indirect + * call with the direct call. + */ + apply_paravirt(__parainstructions, __parainstructions_end); + + /* + * Then patch alternatives, such that those paravirt calls that are in + * alternatives can be overwritten by their immediate fragments. + */ apply_alternatives(__alt_instructions, __alt_instructions_end); #ifdef CONFIG_SMP @@ -748,8 +786,6 @@ void __init alternative_instructions(void) } #endif - apply_paravirt(__parainstructions, __parainstructions_end); - restart_nmi(); alternatives_patched = 1; } -- 2.26.2