From patchwork Fri Jan 6 08:56:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13091171 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 63322C677F1 for ; Fri, 6 Jan 2023 09:21:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233870AbjAFJVY (ORCPT ); Fri, 6 Jan 2023 04:21:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233056AbjAFJUX (ORCPT ); Fri, 6 Jan 2023 04:20:23 -0500 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B47E163188; Fri, 6 Jan 2023 01:20:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672996822; x=1704532822; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=YfKRr1f2yxNCFoiLGWSHFBPe/GqacgdVTltpG9/hhw0=; b=nX3ULDrCXLDvL3JhlJrRX12qeIeXbBafytGsoFUypequb1T90qEPHjTE iPJMu+3sMOLllMrX/W59TBuGWATngbjZ3Fnp/ICUNtcQDqQWpHP4oLkqX OL1qQsfokdX3lK7+lj+KnwVhRUlTf1NJjkkFE9b4x6YwfPtqKoB4sw49x a1y3dstfBSzK/pp4VMCeeSwQXd64hVEGvknphPUPVwCFL0f339yWRjDtq TXCCgIfVIEPf9ACcehlgnyUO4RDjRUpPTHiWyjshEwMUDuMb94FotWO7U CxuYXVdKBfo0EHPQMQSABeKIx30+9RQKcXYh/Cla8BOYu9e6N7ddjz9o5 Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10581"; a="322511542" X-IronPort-AV: E=Sophos;i="5.96,304,1665471600"; d="scan'208";a="322511542" 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 01:20:15 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10581"; a="719139412" X-IronPort-AV: E=Sophos;i="5.96,304,1665471600"; d="scan'208";a="719139412" Received: from unknown (HELO fred..) ([172.25.112.68]) by fmsmga008.fm.intel.com with ESMTP; 06 Jan 2023 01:20:15 -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 19/32] x86/fred: add a NMI entry stub for FRED Date: Fri, 6 Jan 2023 00:56:04 -0800 Message-Id: <20230106085617.17248-20-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)" 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) 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 def4b3455c1f..753ae2adf422 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 cec0bfa3bc04..d497071a79f2 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 @@ -537,6 +538,33 @@ DEFINE_IDTENTRY_RAW(exc_nmi_noist) EXPORT_SYMBOL_GPL(asm_exc_nmi_noist); #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 exit induced by a NMI keeps 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++;