From patchwork Fri Jan 6 08:56:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13091179 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 EB8E8C5479D for ; Fri, 6 Jan 2023 09:22:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232411AbjAFJWA (ORCPT ); Fri, 6 Jan 2023 04:22:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44044 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233135AbjAFJU1 (ORCPT ); Fri, 6 Jan 2023 04:20:27 -0500 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 646006B5DD; Fri, 6 Jan 2023 01:20:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672996826; x=1704532826; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=0gMSYFAIPULPy0xB+8ol1EvYvfgiXDpvvSOWr5aDujM=; b=hJ/GElowOypCvloXZldCmF7Yjeaiedfi0EbjVXKsZnvKI1vHiOKF53wG E+Ge+awFm+7oM+UZyvasp5yQHuI7g+WGwrnogie4obt6dWv0PsbfjjYds iFHgMm13tH2HPG2vh8w3XtzKTuR3oFeUqV9H+82xT4pJvZCM4nXXfznmJ tbvou/zLBWWeRor0CvoXLYUHuo6AdA9VV9xUyPd9nyMCHAWkkMqM8621L KIFt2inIZlPIbco2zzzkeKChQoMf+0AZ/I0NcuCx465QsVwXug9tELYGo Bw1NfcM+H43h1UM2sTrZCGdCHEbRCduxToT+C3M81sOHLLZ3DmFK72ykz g==; X-IronPort-AV: E=McAfee;i="6500,9779,10581"; a="322511621" X-IronPort-AV: E=Sophos;i="5.96,304,1665471600"; d="scan'208";a="322511621" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jan 2023 01:20:17 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10581"; a="719139450" X-IronPort-AV: E=Sophos;i="5.96,304,1665471600"; d="scan'208";a="719139450" Received: from unknown (HELO fred..) ([172.25.112.68]) by fmsmga008.fm.intel.com with ESMTP; 06 Jan 2023 01:20:17 -0800 From: Xin Li To: linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, peterz@infradead.org, andrew.cooper3@citrix.com, seanjc@google.com, pbonzini@redhat.com, ravi.v.shankar@intel.com Subject: [RFC PATCH v2 27/32] x86/fred: allow single-step trap and NMI when starting a new thread Date: Fri, 6 Jan 2023 00:56:12 -0800 Message-Id: <20230106085617.17248-28-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230106085617.17248-1-xin3.li@intel.com> References: <20230106085617.17248-1-xin3.li@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: "H. Peter Anvin (Intel)" Allow single-step trap and NMI when starting a new thread, thus once the new thread returns to ring3, single-step trap and NMI are both enabled immediately. High-order 48 bits above the lowest 16 bit CS are discarded by the legacy IRET instruction, thus can be set unconditionally, even when FRED is not enabled. Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Xin Li --- arch/x86/include/asm/fred.h | 11 +++++++++++ arch/x86/kernel/process_64.c | 13 +++++++------ 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h index 6a417fc1e7ee..958751f16c94 100644 --- a/arch/x86/include/asm/fred.h +++ b/arch/x86/include/asm/fred.h @@ -52,6 +52,14 @@ #define FRED_CSL_ALLOW_SINGLE_STEP _BITUL(25) #define FRED_CSL_INTERRUPT_SHADOW _BITUL(24) +/* + * High-order 48 bits above the lowest 16 bit CS are discarded by the + * legacy IRET instruction, thus can be set unconditionally, even when + * FRED is not enabled. + */ +#define CSL_PROCESS_START \ + (FRED_CSL_ENABLE_NMI | FRED_CSL_ALLOW_SINGLE_STEP) + #ifndef __ASSEMBLY__ #include @@ -115,6 +123,9 @@ void fred_setup_apic(void); #else #define cpu_init_fred_exceptions() BUG() #define fred_setup_apic() BUG() + +#define CSL_PROCESS_START 0 + #endif /* CONFIG_X86_FRED */ #endif /* ASM_X86_FRED_H */ diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 5b6cfd2ca630..128dafc04acf 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -55,6 +55,7 @@ #include #include #include +#include #ifdef CONFIG_IA32_EMULATION /* Not included via unistd.h */ #include @@ -506,7 +507,7 @@ void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase) static void start_thread_common(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp, - unsigned int _cs, unsigned int _ss, unsigned int _ds) + u16 _cs, u16 _ss, u16 _ds) { WARN_ON_ONCE(regs != current_pt_regs()); @@ -521,11 +522,11 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip, loadsegment(ds, _ds); load_gs_index(0); - regs->ip = new_ip; - regs->sp = new_sp; - regs->cs = _cs; - regs->ss = _ss; - regs->flags = X86_EFLAGS_IF; + regs->ip = new_ip; + regs->sp = new_sp; + regs->csl = _cs | CSL_PROCESS_START; + regs->ssl = _ss; + regs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED; } void