From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 EFC81525F for ; Thu, 14 Sep 2023 05:19:22 +0000 (UTC) Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C9D01BD9; Wed, 13 Sep 2023 22:19:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694668762; x=1726204762; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=FcZc1QeKj2isPTwOBVaGNTy+si5WeOaciLFU4yv7EQo=; b=jIncnZMVrIxcwet3pbSY+w+8fYvnN+RdF4lUowsl/oXQDZuU+8ssGNGe 97GTfAOF7Cjr6HxaJ73az9OLXKmMcdxGzANL7FLHEPLGoXOXmZMF3DNOs BYYQ0Ij5CvhNQ8Qw04nATKdmgXkNbd2Qlw/5cerzm6WsXW8vl4Rci25nt 2fn/fRT0knxHPUTw+iy0v4lwJPWuozezZagPZsbuqaoCf9D9cx0UubXxB 5atw500QOMAtwU0NFdxRbsKJuw+znOm4sCy0yoatf8xVBrZCS2fbmiEWk tucqwrhgAEF0zVk4xhw5P2yDPXzs7mkg7dohjxdOORO0uYbXRWG8G5dbw g==; X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="382661407" X-IronPort-AV: E=Sophos;i="6.02,145,1688454000"; d="scan'208";a="382661407" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Sep 2023 22:17:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="779488817" X-IronPort-AV: E=Sophos;i="6.02,145,1688454000"; d="scan'208";a="779488817" Received: from unknown (HELO fred..) ([172.25.112.68]) by orsmga001.jf.intel.com with ESMTP; 13 Sep 2023 22:17:42 -0700 From: Xin Li To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, pbonzini@redhat.com, seanjc@google.com, peterz@infradead.org, jgross@suse.com, ravi.v.shankar@intel.com, mhiramat@kernel.org, andrew.cooper3@citrix.com, jiangshanlai@gmail.com Subject: [PATCH v10 26/38] x86/fred: Add a NMI entry stub for FRED Date: Wed, 13 Sep 2023 21:47:53 -0700 Message-Id: <20230914044805.301390-27-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230914044805.301390-1-xin3.li@intel.com> References: <20230914044805.301390-1-xin3.li@intel.com> Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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/kernel/nmi.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index a0c551846b35..58843fdf5cd0 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 +/* + * With FRED, CR2/DR6 is pushed to #PF/#DB stack frame during FRED + * event delivery, i.e., there is no problem of transient states. + * And NMI unblocking only happens when the stack frame indicates + * that so should happen. + * + * Thus, the NMI entry stub for FRED is really straightforward and + * as simple as most exception handlers. As such, #DB is allowed + * during NMI handling. + */ +DEFINE_FREDENTRY_NMI(exc_nmi) +{ + irqentry_state_t irq_state; + + if (IS_ENABLED(CONFIG_SMP) && arch_cpu_is_offline(smp_processor_id())) + return; + + irq_state = irqentry_nmi_enter(regs); + + inc_irq_stat(__nmi_count); + default_do_nmi(regs); + + irqentry_nmi_exit(regs, irq_state); +} +#endif + void stop_nmi(void) { ignore_nmis++; -- 2.34.1