From nobody Sun Dec 14 19:11:27 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) (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 35ED1EED7 for ; Thu, 22 May 2025 02:45:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.11 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747881942; cv=none; b=jQSOb2vpo21TGE3YM/3oNO6vzQaZlKniv7unsdPLRRfdf59IJ+ABbR4VQS7ZNJmPcBF48hmd7kaKcWIDwMzv9P81gneNEo4sBEkEGvbLXl3kEwkxctuelqna+8qZLP5QL+YwvCfn9Pk+nM6kk/sADbVf1Cx/U8k5pJVPQf2LH9M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747881942; c=relaxed/simple; bh=AzwgqYH4O83LKm2csj9Kj5EkndNBU6z3Sf7FIPsCCbc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iYqa1KOKjVV9ImMnzgQFxLjwpT9LWJdW8fuBbic7m/o0NtL3iOFzWCX7H09hHYKc8g3vqIaBzaSS+MgBfQ1bjzGJTqCxu0ohPkGiDbJx8dDwRbYFvR8mIO56JT9gUcMnu1UW+dtZlf+/UOmyGssdfVdAysvWViMiwFr3srLBTFM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=e4hRQ8gP; arc=none smtp.client-ip=192.198.163.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none 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="e4hRQ8gP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1747881941; x=1779417941; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=AzwgqYH4O83LKm2csj9Kj5EkndNBU6z3Sf7FIPsCCbc=; b=e4hRQ8gPi8rwjO+8grPc1vSVtZ93GhMZKd4KekCH9TGbkDVBjtvvSoJC 7zzl5iYn4ADWXkfNqHnM/UgbQQNEuYXyWoBFkq3SAkbnrUCFrvauXZj/0 fWvPDut0CSa/FWsp88zAnZIX4G1hWZd1+sXLcdccNNtl1ZjCxt3KDa5Zl SYkAswNVr5G2+r+ZMN/CnWPOyASYX/uoLHfnsoLox041kuugiGT6uefvZ besUzATJ0qwSB03s/364l1rc82B3JmDQCYgwJkkfxX9s9D1RFmd2JVQ6a LtlwWj7T774LvIzcXqXiSJZ3Orn5uSJ5NLSXK4iZtbW8SoG5eoHWdqBJJ w==; X-CSE-ConnectionGUID: jhsgjZh/QIue1Lw2wCKt8g== X-CSE-MsgGUID: lX3CoI0XSqSofSmP4Vb/sQ== X-IronPort-AV: E=McAfee;i="6700,10204,11440"; a="60524437" X-IronPort-AV: E=Sophos;i="6.15,305,1739865600"; d="scan'208";a="60524437" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 May 2025 19:45:40 -0700 X-CSE-ConnectionGUID: W8VxJMaDRN2jYBEnzGmtlw== X-CSE-MsgGUID: 37p21kuIR/WXD/F0ga1u8w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,305,1739865600"; d="scan'208";a="141289735" Received: from ssuvarig-mobl.amr.corp.intel.com (HELO desk) ([10.125.146.23]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 May 2025 19:45:40 -0700 Date: Wed, 21 May 2025 19:45:40 -0700 From: Pawan Gupta To: x86@kernel.org Cc: David Kaplan , linux-kernel@vger.kernel.org, "H. Peter Anvin" , Josh Poimboeuf Subject: [PATCH v2 6/7] x86/its: Remove =stuff dependency on retbleed Message-ID: <20250521-eibrs-fix-v2-6-70e2598e932c@linux.intel.com> X-Mailer: b4 0.14.2 References: <20250521-eibrs-fix-v2-0-70e2598e932c@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: <20250521-eibrs-fix-v2-0-70e2598e932c@linux.intel.com> Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow ITS to enable stuffing independent of retbleed. The dependency is only on retpoline. It is a valid case for retbleed to be mitigated by eIBRS while ITS deploys stuffing at the same time. Signed-off-by: Pawan Gupta --- arch/x86/kernel/cpu/bugs.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 59a1f59bf6e2ceda624b6567c5b09ebc524cb9a2..043da9eaf99c5e1f92ae6c56cb7= f779bbceae0e0 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1470,13 +1470,8 @@ static void __init its_update_mitigation(void) break; } =20 - /* - * retbleed_update_mitigation() will try to do stuffing if its=3Dstuff. - * If it can't, such as if spectre_v2!=3Dretpoline, then fall back to - * aligned thunks. - */ if (its_mitigation =3D=3D ITS_MITIGATION_RETPOLINE_STUFF && - retbleed_mitigation !=3D RETBLEED_MITIGATION_STUFF) + !cdt_possible(spectre_v2_enabled)) its_mitigation =3D ITS_MITIGATION_ALIGNED_THUNKS; =20 pr_info("%s\n", its_strings[its_mitigation]); @@ -1488,8 +1483,6 @@ static void __init its_apply_mitigation(void) case ITS_MITIGATION_OFF: case ITS_MITIGATION_AUTO: case ITS_MITIGATION_VMEXIT_ONLY: - /* its=3Dstuff forces retbleed stuffing and is enabled there. */ - case ITS_MITIGATION_RETPOLINE_STUFF: break; case ITS_MITIGATION_ALIGNED_THUNKS: if (!boot_cpu_has(X86_FEATURE_RETPOLINE)) @@ -1498,6 +1491,11 @@ static void __init its_apply_mitigation(void) setup_force_cpu_cap(X86_FEATURE_RETHUNK); set_return_thunk(its_return_thunk); break; + case ITS_MITIGATION_RETPOLINE_STUFF: + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH); + set_return_thunk(call_depth_return_thunk); + break; } } =20 --=20 2.34.1