From mboxrd@z Thu Jan 1 00:00:00 1970 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 03ED6C001DB for ; Thu, 10 Aug 2023 13:41:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234035AbjHJNlD (ORCPT ); Thu, 10 Aug 2023 09:41:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235417AbjHJNlA (ORCPT ); Thu, 10 Aug 2023 09:41:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 331B0211D for ; Thu, 10 Aug 2023 06:40:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id BD05964BCE for ; Thu, 10 Aug 2023 13:40:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7887C433C8; Thu, 10 Aug 2023 13:40:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691674858; bh=Boi2EmBcvRwZaghQ8cLIVs6Ifp4ejTuFCmJKUXfXouA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZnttkvoQLkZnzcPaHupkf4DN/nU0OmLYBjgnnmxk8MeRiUV4/QD1z94LgCez09dFh 53hUjN0w7MctVFCyRvXBKDQTz027zFzM+8J7IWqSgv90AoZY9UhiwQPxOi9Glt+B6k 97TgYPyeiD/X1/JifPyWf5dDDNNFpEHvNiSi+4MPLjOTPvHffbnGgrj5N6A/0kGrND Ef7Im1h/TdiYDEFa3AMPAfKdrOr6+ha1X9sTXhHroerHlpdPanU5pZBDpy0c8oubiL n3oeX+KoTYIb2Hgpt+o11o4qu+uWX8HA/fQ6JHZJorT9BU3ZZm5AkPS57JMZy3noCg 0gtcFJ6Go/7AA== Date: Thu, 10 Aug 2023 06:40:56 -0700 From: Nathan Chancellor To: Borislav Petkov Cc: x86@kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: Hang when booting guest kernels compiled with clang after SRSO mitigations Message-ID: <20230810134056.GA130730@dev-arch.thelio-3990X> References: <20230810013334.GA5354@dev-arch.thelio-3990X> <20230810081038.GAZNSbftb6DOgg/U7e@fat_crate.local> <20230810090835.GBZNSpE6tCw+Ci+9yh@fat_crate.local> <20230810101649.GA1795474@dev-arch.thelio-3990X> <20230810125122.GIZNTdSuFvA3Cjfexq@fat_crate.local> <20230810132706.GA3805855@dev-arch.thelio-3990X> <20230810133216.GKZNTm4KpohRR4gVsT@fat_crate.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230810133216.GKZNTm4KpohRR4gVsT@fat_crate.local> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 10, 2023 at 03:32:16PM +0200, Borislav Petkov wrote: > On Thu, Aug 10, 2023 at 06:27:06AM -0700, Nathan Chancellor wrote: > > But my host kernel was compiled using GCC 13.2.0 from kernel.org for the > > sake of testing to see if the compiler used to build the host kernel had > > an impact on the problem and it did not. > > Ok, now I'm confused. Heh, so was I at first when I was doing my regular build and boot tests of -next :P > Lemme see if I understand it correctly: > > host kernel: > - SRSO enabled > - built with gcc > > guest kernel: > - built with clang > - SRSO not necessary > > Is that the scenario? Yes, that should be correct. Host kernel string: 6.5.0-rc5-00039-g138bcddb86d8 (nathan@dev-arch.thelio-3990X) (x86_64-linux-gcc (GCC) 13.2.0, GNU ld (GNU Binutils) 2.41) #1 SMP PREEMPT_DYNAMIC Wed Aug 9 17:34:43 MST 2023 Guest kernel string: 6.5.0-rc5 (nathan@dev-arch.thelio-3990X) (ClangBuiltLinux clang version 16.0.6 (https://github.com/llvm/llvm-project 7cbf1a2591520c2491aa35339f227775f4d3adf6), GNU ld (GNU Binutils) 2.41.50.20230809) #1 SMP PREEMPT_DYNAMIC Wed Aug 9 16:54:33 MST 2023 > Anything else? Shouldn't be. As I noted in the original email, it seems something specific to the safe-ret mitigation as I don't see the problem with ibpb, that would be a good canary for making sure that you see the same behavior. Cheers, Nathan