From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AB299824B3; Mon, 15 Apr 2024 14:37:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713191858; cv=none; b=jUh7PxfU0GRoFeinQ+t1ehUJr67oCKGj//KtngwCz7g+MGHd8f/vWPnhAIVG5QsLI8ruOB2AIpP3CkUxFQsmRcKmej5eM/vthd6Xb5qFpNvSlbcyFqjtC58U0w7HFvKmaqsAUoL0eSETuUJSmYdcPDjah8QIIciuCqS1Hq1tw+E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713191858; c=relaxed/simple; bh=ZauY8dF6RYaXiFHRPKnDTaNY2LkEk6rJ9N0AFNvlB/E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=V5d68WYv+uUBNwVYvcxNw01h9DZMT0Q1zXhZOsRu/kTzvWheutHwKj0s4n+LmvtGn+nNwsrihqN/r3UwiR7Ew8JtrYfdMti3AqLrYb2UdG7VsR+1kaWcaf1Rv2047COoB+UnLxSwrCFb7z3gH9vI4+JGP1pZYlGAeAREPwaadrw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=z80QKmys; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="z80QKmys" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3D32C113CC; Mon, 15 Apr 2024 14:37:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1713191858; bh=ZauY8dF6RYaXiFHRPKnDTaNY2LkEk6rJ9N0AFNvlB/E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z80QKmysYQiOFmhxviawjHHY7rlmkvC9XppZQrXe1FRoJ24lYqH1Zpc4Pmf21gVT+ V9rLAxvN+yhrH5WW1a/9nBiYtCt9r/uIcOaUrAzlWygW1leupgW0/KHHuWc2AsWmIp HqGYPdRaaHCtjXs7keLizo/jlYnq139MfyOyfQro= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josh Poimboeuf , Ingo Molnar , Nikolay Borisov , Linus Torvalds , Sean Christopherson Subject: [PATCH 6.6 109/122] x86/bugs: Cache the value of MSR_IA32_ARCH_CAPABILITIES Date: Mon, 15 Apr 2024 16:21:14 +0200 Message-ID: <20240415141956.643592447@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240415141953.365222063@linuxfoundation.org> References: <20240415141953.365222063@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf commit cb2db5bb04d7f778fbc1a1ea2507aab436f1bff3 upstream. There's no need to keep reading MSR_IA32_ARCH_CAPABILITIES over and over. It's even read in the BHI sysfs function which is a big no-no. Just read it once and cache it. Fixes: ec9404e40e8f ("x86/bhi: Add BHI mitigation knob") Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Reviewed-by: Nikolay Borisov Cc: Linus Torvalds Cc: Sean Christopherson Link: https://lore.kernel.org/r/9592a18a814368e75f8f4b9d74d3883aa4fd1eaf.1712813475.git.jpoimboe@kernel.org Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -61,6 +61,8 @@ EXPORT_SYMBOL_GPL(x86_spec_ctrl_current) u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB; EXPORT_SYMBOL_GPL(x86_pred_cmd); +static u64 __ro_after_init ia32_cap; + static DEFINE_MUTEX(spec_ctrl_mutex); void (*x86_return_thunk)(void) __ro_after_init = __x86_return_thunk; @@ -144,6 +146,8 @@ void __init cpu_select_mitigations(void) x86_spec_ctrl_base &= ~SPEC_CTRL_MITIGATIONS_MASK; } + ia32_cap = x86_read_arch_cap_msr(); + /* Select the proper CPU mitigations before patching alternatives: */ spectre_v1_select_mitigation(); spectre_v2_select_mitigation(); @@ -301,8 +305,6 @@ static const char * const taa_strings[] static void __init taa_select_mitigation(void) { - u64 ia32_cap; - if (!boot_cpu_has_bug(X86_BUG_TAA)) { taa_mitigation = TAA_MITIGATION_OFF; return; @@ -341,7 +343,6 @@ static void __init taa_select_mitigation * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode * update is required. */ - ia32_cap = x86_read_arch_cap_msr(); if ( (ia32_cap & ARCH_CAP_MDS_NO) && !(ia32_cap & ARCH_CAP_TSX_CTRL_MSR)) taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; @@ -401,8 +402,6 @@ static const char * const mmio_strings[] static void __init mmio_select_mitigation(void) { - u64 ia32_cap; - if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) || boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN) || cpu_mitigations_off()) { @@ -413,8 +412,6 @@ static void __init mmio_select_mitigatio if (mmio_mitigation == MMIO_MITIGATION_OFF) return; - ia32_cap = x86_read_arch_cap_msr(); - /* * Enable CPU buffer clear mitigation for host and VMM, if also affected * by MDS or TAA. Otherwise, enable mitigation for VMM only. @@ -508,7 +505,7 @@ static void __init rfds_select_mitigatio if (rfds_mitigation == RFDS_MITIGATION_OFF) return; - if (x86_read_arch_cap_msr() & ARCH_CAP_RFDS_CLEAR) + if (ia32_cap & ARCH_CAP_RFDS_CLEAR) setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); else rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED; @@ -659,8 +656,6 @@ void update_srbds_msr(void) static void __init srbds_select_mitigation(void) { - u64 ia32_cap; - if (!boot_cpu_has_bug(X86_BUG_SRBDS)) return; @@ -669,7 +664,6 @@ static void __init srbds_select_mitigati * are only exposed to SRBDS when TSX is enabled or when CPU is affected * by Processor MMIO Stale Data vulnerability. */ - ia32_cap = x86_read_arch_cap_msr(); if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) && !boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) srbds_mitigation = SRBDS_MITIGATION_TSX_OFF; @@ -813,7 +807,7 @@ static void __init gds_select_mitigation /* Will verify below that mitigation _can_ be disabled */ /* No microcode */ - if (!(x86_read_arch_cap_msr() & ARCH_CAP_GDS_CTRL)) { + if (!(ia32_cap & ARCH_CAP_GDS_CTRL)) { if (gds_mitigation == GDS_MITIGATION_FORCE) { /* * This only needs to be done on the boot CPU so do it @@ -1907,8 +1901,6 @@ static void update_indir_branch_cond(voi /* Update the static key controlling the MDS CPU buffer clear in idle */ static void update_mds_branch_idle(void) { - u64 ia32_cap = x86_read_arch_cap_msr(); - /* * Enable the idle clearing if SMT is active on CPUs which are * affected only by MSBDS and not any other MDS variant. @@ -2817,7 +2809,7 @@ static const char *spectre_bhi_state(voi else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP)) return "; BHI: SW loop, KVM: SW loop"; else if (boot_cpu_has(X86_FEATURE_RETPOLINE) && - !(x86_read_arch_cap_msr() & ARCH_CAP_RRSBA)) + !(ia32_cap & ARCH_CAP_RRSBA)) return "; BHI: Retpoline"; else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT)) return "; BHI: Syscall hardening, KVM: SW loop";