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 D21CFC6FD1D for ; Mon, 20 Mar 2023 17:03:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233316AbjCTRDP (ORCPT ); Mon, 20 Mar 2023 13:03:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231924AbjCTRCt (ORCPT ); Mon, 20 Mar 2023 13:02:49 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 206511C310; Mon, 20 Mar 2023 09:56:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ss3pf4bw0TX+NsOEXdlAuLxz+g7l7ioANkWaEdO4Rho=; b=Syk0qamgSajvba6KPCkW3IFwxF 51I7q6SCzuEvk5g8fN4wxiSzwf340m5ARex+1lMcoyh35XGdgkGidX/vyvYl8cvgKs2t+qNpM8R5G qWSL08Tch/Go0ZufM1mFChOncQjezMvd3t5kmZGHepXbdHO6kCGKpXJbJrKYeOoOnNnBcmdtK3wkJ HrdgwuoB2EvwTWT3xe8URohshQe6cMQdeZSOFzBfgbC+Nygo1bRkyg7JGTdpo6c0mHlSdiUUCcXwH H/DtxUhgR/xNVT6d63cpA6maGUixTxsXwoCoLMjy3kne0Z1yxznfSD2LtWIzA6xDtJZXMHlBh7pT3 zcmRVh6A==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1peIlv-003zuP-3C; Mon, 20 Mar 2023 16:54:12 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 89015300642; Mon, 20 Mar 2023 17:54:11 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7B021200A76E5; Mon, 20 Mar 2023 17:54:11 +0100 (CET) Date: Mon, 20 Mar 2023 17:54:11 +0100 From: Peter Zijlstra To: Xin Li Cc: linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, andrew.cooper3@citrix.com, seanjc@google.com, pbonzini@redhat.com, ravi.v.shankar@intel.com Subject: Re: [PATCH v5 25/34] x86/fred: disallow the swapgs instruction when FRED is enabled Message-ID: <20230320165411.GT2194297@hirez.programming.kicks-ass.net> References: <20230307023946.14516-1-xin3.li@intel.com> <20230307023946.14516-26-xin3.li@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230307023946.14516-26-xin3.li@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 06, 2023 at 06:39:37PM -0800, Xin Li wrote: > From: "H. Peter Anvin (Intel)" > > The FRED architecture establishes the full supervisor/user through: > 1) FRED event delivery swaps the value of the GS base address and > that of the IA32_KERNEL_GS_BASE MSR. > 2) ERETU swaps the value of the GS base address and that of the > IA32_KERNEL_GS_BASE MSR. > Thus, the swapgs instruction is disallowed when FRED is enabled, > otherwise it cauess #UD. ^^^ --- new word :-)