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X-CSE-ConnectionGUID: S3xnyGONSM6FdwY+uMvmAQ== X-CSE-MsgGUID: 4I+I/b4hTW63wZ3Cg81Uqw== X-IronPort-AV: E=McAfee;i="6800,10657,11711"; a="83696385" X-IronPort-AV: E=Sophos;i="6.21,309,1763452800"; d="scan'208";a="83696385" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Feb 2026 10:22:37 -0800 X-CSE-ConnectionGUID: o/17PFgXSwGl7DplXy5bbg== X-CSE-MsgGUID: qOYXcZTcQMSSYspjpo9T9w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,309,1763452800"; d="scan'208";a="220586598" Received: from schen9-mobl4.amr.corp.intel.com (HELO [10.125.111.27]) ([10.125.111.27]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Feb 2026 10:22:36 -0800 Message-ID: <6b3b0c86-99eb-406d-b88d-3d71613bef9e@intel.com> Date: Tue, 24 Feb 2026 10:22:36 -0800 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] cpu/bugs: Fix selecting Automatic IBRS using spectre_v2=eibrs To: Kim Phillips , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, x86@kernel.org Cc: Sean Christopherson , Paolo Bonzini , K Prateek Nayak , Nikunj A Dadhania , Tom Lendacky , Michael Roth , Borislav Petkov , Borislav Petkov , Naveen Rao , David Kaplan , Pawan Gupta , stable@kernel.org References: <20260224180157.725159-1-kim.phillips@amd.com> <20260224180157.725159-2-kim.phillips@amd.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/24/26 10:01, Kim Phillips wrote: > @@ -2136,7 +2136,8 @@ static void __init spectre_v2_select_mitigation(void) > if ((spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS || > spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || > spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && > - !boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { > + !(boot_cpu_has(X86_FEATURE_IBRS_ENHANCED) || > + boot_cpu_has(X86_FEATURE_AUTOIBRS))) { > pr_err("EIBRS selected but CPU doesn't have Enhanced or Automatic IBRS. Switching to AUTO select\n"); > spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; > } Didn't we agree to just use the "Intel feature" name? See this existing code: > /* > * AMD's AutoIBRS is equivalent to Intel's eIBRS - use the Intel feature > * flag and protect from vendor-specific bugs via the whitelist. > * > * Don't use AutoIBRS when SNP is enabled because it degrades host > * userspace indirect branch performance. > */ > if ((x86_arch_cap_msr & ARCH_CAP_IBRS_ALL) || > (cpu_has(c, X86_FEATURE_AUTOIBRS) && > !cpu_feature_enabled(X86_FEATURE_SEV_SNP))) { > setup_force_cpu_cap(X86_FEATURE_IBRS_ENHANCED); > if (!cpu_matches(cpu_vuln_whitelist, NO_EIBRS_PBRSB) && > !(x86_arch_cap_msr & ARCH_CAP_PBRSB_NO)) > setup_force_cpu_bug(X86_BUG_EIBRS_PBRSB); > } You're probably not seeing X86_FEATURE_IBRS_ENHANCED because it doesn't get forced under SNP.