From patchwork Tue Mar 7 02:39:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13162694 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 48AECC64EC4 for ; Tue, 7 Mar 2023 03:06:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230432AbjCGDGu (ORCPT ); Mon, 6 Mar 2023 22:06:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230337AbjCGDF7 (ORCPT ); Mon, 6 Mar 2023 22:05:59 -0500 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BEA23CE31; Mon, 6 Mar 2023 19:05:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1678158331; x=1709694331; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=siTNXpO7BJ/4zV0VfXO5tCEXqrBwC+DhXoQqxTjs92s=; b=MNhw3qM1aL+GklOWcAb2uVDBdjdHlCaCPJtDJRW7BIfviYYd+CEicXBM vS8ES3rcFvIEO1dwua9d5H0pfSfKC/BjJGf0gL94L2iygl0PLtDhj92kx SEHLImRDl2EG2rLq73gPcOv/Awuwj2GBYJ00WdvWyjyTm6Ee/ZcQPY0OE 8TCCEfJcfvaZ/11mHiZQMVzQEXGdlAfVBrYHsdurzjtbErXmH/UVla+IX bcl5SPEKBESO61V9zKvnWT+3xYb+2kIiBzCm29FgnsUIK+FEGxNB2fJ2a gr1pZz0vHial8j+YqZg4n99PsChZSyG/gClnPiSKkukU2tV+Jp9WiHGHj A==; X-IronPort-AV: E=McAfee;i="6500,9779,10641"; a="338072486" X-IronPort-AV: E=Sophos;i="5.98,238,1673942400"; d="scan'208";a="338072486" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2023 19:05:18 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10641"; a="676409846" X-IronPort-AV: E=Sophos;i="5.98,238,1673942400"; d="scan'208";a="676409846" Received: from unknown (HELO fred..) ([172.25.112.68]) by orsmga002.jf.intel.com with ESMTP; 06 Mar 2023 19:05:17 -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: [PATCH v5 19/34] x86/fred: add a NMI entry stub for FRED Date: Mon, 6 Mar 2023 18:39:31 -0800 Message-Id: <20230307023946.14516-20-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230307023946.14516-1-xin3.li@intel.com> References: <20230307023946.14516-1-xin3.li@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: "H. Peter Anvin (Intel)" On a FRED system, NMIs nest both with themselves and faults, transient information is saved into the stack frame, and NMI unblocking only happens when the stack frame indicates that so should happen. Thus, the NMI entry stub for FRED is really quite small... Signed-off-by: H. Peter Anvin (Intel) Tested-by: Shan Kang Signed-off-by: Xin Li --- arch/x86/include/asm/fred.h | 1 + arch/x86/kernel/nmi.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h index 633dd9e6a68e..f928a03082af 100644 --- a/arch/x86/include/asm/fred.h +++ b/arch/x86/include/asm/fred.h @@ -94,6 +94,7 @@ static __always_inline unsigned long fred_event_data(struct pt_regs *regs) #define DEFINE_FRED_HANDLER(f) noinstr DECLARE_FRED_HANDLER(f) typedef DECLARE_FRED_HANDLER((*fred_handler)); +DECLARE_FRED_HANDLER(fred_exc_nmi); DECLARE_FRED_HANDLER(fred_exc_debug); DECLARE_FRED_HANDLER(fred_exc_page_fault); diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 776f4b1e395b..1deedfd6de69 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -34,6 +34,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -643,6 +644,33 @@ void nmi_backtrace_stall_check(const struct cpumask *btp) #endif +#ifdef CONFIG_X86_FRED +DEFINE_FRED_HANDLER(fred_exc_nmi) +{ + /* + * With FRED, CR2 and DR6 are pushed atomically on faults, + * so we don't have to worry about saving and restoring them. + * Breakpoint faults nest, so assume it is OK to leave DR7 + * enabled. + */ + irqentry_state_t irq_state = irqentry_nmi_enter(regs); + + /* + * VM exits induced by NMIs keep NMI blocked, and we do + * "int $2" to reinject the NMI w/ NMI kept being blocked. + * However "int $2" doesn't set the nmi bit in the FRED + * stack frame, so we explicitly set it to make sure a + * later ERETS will unblock NMI immediately. + */ + regs->nmi = 1; + + inc_irq_stat(__nmi_count); + default_do_nmi(regs); + + irqentry_nmi_exit(regs, irq_state); +} +#endif + void stop_nmi(void) { ignore_nmis++;