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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 532FDEB64DD for ; Wed, 9 Aug 2023 07:27:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231786AbjHIH1q (ORCPT ); Wed, 9 Aug 2023 03:27:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231534AbjHIH1D (ORCPT ); Wed, 9 Aug 2023 03:27:03 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EFCC7172A for ; Wed, 9 Aug 2023 00:27:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=8xFU9MBBRCXYqcJsEM5lvzkq5hInOlKwoKgeAy28v10=; b=EajMsa8j7ET1nFWY7bCbGtfEDw 0CBpeSECh8MfbWfhOl9u4tWKKqlAqaQkwaXaSa1d6nFKLOeo6R5eMjB4OXYavYxt7Q3Js7SD1MY9m 5qZJ6H/JlRh/SScwrpc8/e9cFA2D7PC4gqGn5Tf8QxbATfPY9YCbil4gclo7Z+QtyNP6pDsXvCjVn S3Z7Vfehk9s1ovI/9a8+eLbe9NUzLgb6/AdkARaAmq4pqdNGnfImI67g3b1UWQAfQKf69gD0uHEHL cMlWyBC5VFpxxyteSUvl0AQco39jlY/g8muU9AmEbiw6vEN40+c38fJiRFR6Lwt2ExUzJv4oC9BZW c0N8Zxdw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qTdag-004olT-3p; Wed, 09 Aug 2023 07:26:46 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 96AF430067B; Wed, 9 Aug 2023 09:26:44 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 5FAC82CEC71E0; Wed, 9 Aug 2023 09:26:44 +0200 (CEST) Message-ID: <20230809072200.922634286@infradead.org> User-Agent: quilt/0.66 Date: Wed, 09 Aug 2023 09:12:25 +0200 From: Peter Zijlstra To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, David.Kaplan@amd.com, Andrew.Cooper3@citrix.com, jpoimboe@kernel.org, gregkh@linuxfoundation.org Subject: [RFC][PATCH 07/17] x86/cpu/kvm: Provide UNTRAIN_RET_VM References: <20230809071218.000335006@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With the difference being that UNTRAIN_RET_VM uses X86_FEATURE_IBPB_ON_VMEXIT instead of X86_FEATURE_ENTRY_IBPB. This cures VMEXIT doing potentially unret+IBPB or double IBPB. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/include/asm/nospec-branch.h | 11 +++++++++++ arch/x86/kernel/cpu/bugs.c | 17 ++++++++++++++++- arch/x86/kvm/svm/vmenter.S | 7 ++----- 3 files changed, 29 insertions(+), 6 deletions(-) --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -299,6 +299,17 @@ #endif .endm +.macro UNTRAIN_RET_VM +#if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \ + defined(CONFIG_CALL_DEPTH_TRACKING) || defined(CONFIG_CPU_SRSO) + VALIDATE_UNRET_END + ALTERNATIVE_3 "", \ + CALL_UNTRAIN_RET, X86_FEATURE_UNRET, \ + "call entry_ibpb", X86_FEATURE_IBPB_ON_VMEXIT, \ + __stringify(RESET_CALL_DEPTH), X86_FEATURE_CALL_DEPTH +#endif +.endm + .macro UNTRAIN_RET_FROM_CALL #if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \ defined(CONFIG_CALL_DEPTH_TRACKING) --- a/arch/x86/kvm/svm/vmenter.S +++ b/arch/x86/kvm/svm/vmenter.S @@ -222,10 +222,7 @@ SYM_FUNC_START(__svm_vcpu_run) * because interrupt handlers won't sanitize 'ret' if the return is * from the kernel. */ - UNTRAIN_RET - - /* SRSO */ - ALTERNATIVE "", "call entry_ibpb", X86_FEATURE_IBPB_ON_VMEXIT + UNTRAIN_RET_VM /* * Clear all general purpose registers except RSP and RAX to prevent @@ -362,7 +359,7 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run) * because interrupt handlers won't sanitize RET if the return is * from the kernel. */ - UNTRAIN_RET + UNTRAIN_RET_VM /* "Pop" @spec_ctrl_intercepted. */ pop %_ASM_BX