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 6C9FECCA47F for ; Tue, 12 Jul 2022 18:55:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234915AbiGLSzh (ORCPT ); Tue, 12 Jul 2022 14:55:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234787AbiGLSyi (ORCPT ); Tue, 12 Jul 2022 14:54:38 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 592BFE95F8; Tue, 12 Jul 2022 11:46:06 -0700 (PDT) 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 dfw.source.kernel.org (Postfix) with ESMTPS id BC43160A1C; Tue, 12 Jul 2022 18:46:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB91BC3411C; Tue, 12 Jul 2022 18:46:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657651565; bh=rn3X5p8IfphIAOw9YW6Id6cWDmF/8gFuGDqC30KUOfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qZb0a6XuOSLa+mhzZgOvHpbQLMN448pu3H7MbeL6kN3V5qp3NPbEjklXW4fwnvItD V5SnIoneL04Lrn8oy4he0xKHNRyIN6zneqRtoQtqR6JqPimNSJKuwD3xqW4/P2P9fQ eXqcAVTmLVXwA2UCGAowAYiZ8GzdTidMaF2ZyMqk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josh Poimboeuf , Borislav Petkov , Paolo Bonzini , Thadeu Lima de Souza Cascardo , Ben Hutchings Subject: [PATCH 5.10 116/130] x86/speculation: Remove x86_spec_ctrl_mask Date: Tue, 12 Jul 2022 20:39:22 +0200 Message-Id: <20220712183251.809364205@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220712183246.394947160@linuxfoundation.org> References: <20220712183246.394947160@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Josh Poimboeuf commit acac5e98ef8d638a411cfa2ee676c87e1973f126 upstream. This mask has been made redundant by kvm_spec_ctrl_test_value(). And it doesn't even work when MSR interception is disabled, as the guest can just write to SPEC_CTRL directly. Signed-off-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Reviewed-by: Paolo Bonzini Signed-off-by: Borislav Petkov Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 31 +------------------------------ 1 file changed, 1 insertion(+), 30 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -85,12 +85,6 @@ u64 spec_ctrl_current(void) EXPORT_SYMBOL_GPL(spec_ctrl_current); /* - * The vendor and possibly platform specific bits which can be modified in - * x86_spec_ctrl_base. - */ -static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS; - -/* * AMD specific MSR info for Speculative Store Bypass control. * x86_amd_ls_cfg_ssbd_mask is initialized in identify_boot_cpu(). */ @@ -138,10 +132,6 @@ void __init check_bugs(void) if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) rdmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); - /* Allow STIBP in MSR_SPEC_CTRL if supported */ - if (boot_cpu_has(X86_FEATURE_STIBP)) - x86_spec_ctrl_mask |= SPEC_CTRL_STIBP; - /* Select the proper CPU mitigations before patching alternatives: */ spectre_v1_select_mitigation(); spectre_v2_select_mitigation(); @@ -199,19 +189,10 @@ void __init check_bugs(void) void x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) { - u64 msrval, guestval, hostval = spec_ctrl_current(); + u64 msrval, guestval = guest_spec_ctrl, hostval = spec_ctrl_current(); struct thread_info *ti = current_thread_info(); - /* Is MSR_SPEC_CTRL implemented ? */ if (static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) { - /* - * Restrict guest_spec_ctrl to supported values. Clear the - * modifiable bits in the host base value and or the - * modifiable bits from the guest value. - */ - guestval = hostval & ~x86_spec_ctrl_mask; - guestval |= guest_spec_ctrl & x86_spec_ctrl_mask; - if (hostval != guestval) { msrval = setguest ? guestval : hostval; wrmsrl(MSR_IA32_SPEC_CTRL, msrval); @@ -1622,16 +1603,6 @@ static enum ssb_mitigation __init __ssb_ } /* - * If SSBD is controlled by the SPEC_CTRL MSR, then set the proper - * bit in the mask to allow guests to use the mitigation even in the - * case where the host does not enable it. - */ - if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || - static_cpu_has(X86_FEATURE_AMD_SSBD)) { - x86_spec_ctrl_mask |= SPEC_CTRL_SSBD; - } - - /* * We have three CPU feature flags that are in play here: * - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible. * - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass