From nobody Mon Apr 6 12:11:12 2026 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 297673E3173; Thu, 19 Mar 2026 15:41:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.19 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773934895; cv=none; b=GM/VvxsPuSyWYUl4sjUy+fw/vykTIR3Y597WRzkRjv7QX8GiyVIiuVCvKbLguFO8Vj6nMHOy4geB3Y5faq5FTrUDyslq51fcjMQD36GxN/UPxFrL1UYPNX2bKlwiT2SGhHpzXuYWO1gSKvCqW45xR+kCoJRnzZSoy/Z4XeBXWNQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773934895; c=relaxed/simple; bh=iKbYaTDuUMcCWsnSDj/iaOVKUwO2Qpaue4niM52YYmE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WODaoe0oQIc5UX8Yn+V+0MnKNRFBHezF8PSGGcU9+vLyjqiNFQo85H5gdrG/DcHju62G4IQWVCcijtJ5uiQGQUmn0wUZ/7OYD9sdc7crhQyUIgH0x2YpHFjZdxMwUVIgSldZi0gqtyflAQEFyiyDD1isNWJnv0fPdpCyWv2lCYY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=dJZV8fi2; arc=none smtp.client-ip=198.175.65.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="dJZV8fi2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1773934894; x=1805470894; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=iKbYaTDuUMcCWsnSDj/iaOVKUwO2Qpaue4niM52YYmE=; b=dJZV8fi2so7hMaDmuNH437zwKEJgbGPsesUf3PkDUCuIrWwSsdyibDe7 PVyYJRlJDmL7dDYg0l2hsYBxY8FjOvF14mkvPl1Xp9Zpi0RxPcSOl+b6s bZlpzkEQisPp7gsHdUFCu6ffptC6zasKzvNktouh8+XHg33voaZDzvBkR EsFLxvv6dHX3dMYYw9LI3aWB/6dI/dZONig+iPxuImxKztrASi0rfcDw+ ONcE/Tq+PjltVm8wuvtQvkoUt+QdIipPNd2r/3owMIAB7gfremjhmEY+i j8GtvHrGIF6Ec0XjSDgP7axK5Y/c/dSZIRb6Rd+F7S2DSi+MiMOS9Qmv7 Q==; X-CSE-ConnectionGUID: U5BIXzFPQtKhrOhBXZ500g== X-CSE-MsgGUID: 8oGDNpb3TmqPOzYi5Y//Ag== X-IronPort-AV: E=McAfee;i="6800,10657,11734"; a="74896025" X-IronPort-AV: E=Sophos;i="6.23,129,1770624000"; d="scan'208";a="74896025" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2026 08:41:25 -0700 X-CSE-ConnectionGUID: xOqiReMuTuW2yq9F3TQlbw== X-CSE-MsgGUID: iNeeHwfvSyuH0dAxrQj3Tg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,129,1770624000"; d="scan'208";a="246015472" Received: from guptapa-desk.jf.intel.com (HELO desk) ([10.165.239.46]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2026 08:41:23 -0700 Date: Thu, 19 Mar 2026 08:41:22 -0700 From: Pawan Gupta To: x86@kernel.org, Nikolay Borisov , "H. Peter Anvin" , Josh Poimboeuf , David Kaplan , Sean Christopherson , Borislav Petkov , Dave Hansen , Peter Zijlstra , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , KP Singh , Jiri Olsa , "David S. Miller" , David Laight , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , David Ahern , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , Stanislav Fomichev , Hao Luo , Paolo Bonzini , Jonathan Corbet Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Asit Mallick , Tao Zhang , bpf@vger.kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org Subject: [PATCH v7 05/10] x86/vmscape: Move mitigation selection to a switch() Message-ID: <20260319-vmscape-bhb-v7-5-b76a777a98af@linux.intel.com> X-Mailer: b4 0.15-dev References: <20260319-vmscape-bhb-v7-0-b76a777a98af@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20260319-vmscape-bhb-v7-0-b76a777a98af@linux.intel.com> Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This ensures that all mitigation modes are explicitly handled, while keeping the mitigation selection for each mode together. This also prepares for adding BHB-clearing mitigation mode for VMSCAPE. Reviewed-by: Nikolay Borisov Signed-off-by: Pawan Gupta --- arch/x86/kernel/cpu/bugs.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 47c020b80371..68e2df3e3bf5 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -3084,17 +3084,33 @@ early_param("vmscape", vmscape_parse_cmdline); =20 static void __init vmscape_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_VMSCAPE) || - !boot_cpu_has(X86_FEATURE_IBPB)) { + if (!boot_cpu_has_bug(X86_BUG_VMSCAPE)) { vmscape_mitigation =3D VMSCAPE_MITIGATION_NONE; return; } =20 - if (vmscape_mitigation =3D=3D VMSCAPE_MITIGATION_AUTO) { - if (should_mitigate_vuln(X86_BUG_VMSCAPE)) + if ((vmscape_mitigation =3D=3D VMSCAPE_MITIGATION_AUTO) && + !should_mitigate_vuln(X86_BUG_VMSCAPE)) + vmscape_mitigation =3D VMSCAPE_MITIGATION_NONE; + + switch (vmscape_mitigation) { + case VMSCAPE_MITIGATION_NONE: + break; + + case VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER: + if (!boot_cpu_has(X86_FEATURE_IBPB)) + vmscape_mitigation =3D VMSCAPE_MITIGATION_NONE; + break; + + case VMSCAPE_MITIGATION_AUTO: + if (boot_cpu_has(X86_FEATURE_IBPB)) vmscape_mitigation =3D VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER; else vmscape_mitigation =3D VMSCAPE_MITIGATION_NONE; + break; + + default: + break; } } =20 --=20 2.34.1