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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 54024C02192 for ; Wed, 5 Feb 2025 09:38:38 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.882023.1292194 (Exim 4.92) (envelope-from ) id 1tfbrV-0004b5-AG; Wed, 05 Feb 2025 09:38:25 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 882023.1292194; Wed, 05 Feb 2025 09:38:25 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1tfbrV-0004ay-6A; Wed, 05 Feb 2025 09:38:25 +0000 Received: by outflank-mailman (input) for mailman id 882023; Wed, 05 Feb 2025 09:38:24 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1tfbrU-0004as-82 for xen-devel@lists.xenproject.org; Wed, 05 Feb 2025 09:38:24 +0000 Received: from mail-wr1-x434.google.com (mail-wr1-x434.google.com [2a00:1450:4864:20::434]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id f0552c49-e3a4-11ef-99a4-01e77a169b0f; Wed, 05 Feb 2025 10:38:22 +0100 (CET) Received: by mail-wr1-x434.google.com with SMTP id ffacd0b85a97d-38da88e6db0so831020f8f.2 for ; Wed, 05 Feb 2025 01:38:22 -0800 (PST) Received: from [192.168.1.10] (host-92-26-98-202.as13285.net. [92.26.98.202]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38db0e2f479sm3061238f8f.57.2025.02.05.01.38.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 Feb 2025 01:38:20 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: f0552c49-e3a4-11ef-99a4-01e77a169b0f DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1738748301; x=1739353101; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=7c3hH/C0ty80foBKuB31iqczubI+r+OraZ1ZxIaqE7Y=; b=UjhMkkwySzbNwmnjwx+9I+MRhh7gXQVTNxZjtSweV1YIzLKyPb48KFftpPBBuEaYT0 Wjlo3on39tRLg0Diy/5Frhv+BNbNpRcQbSSNo1Qb78fZkqUriFoVlHqZBIaYWX14lJWK /hUxVBiyY82sWgbDENL70uDvN/4Lbh6D8c57I= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738748301; x=1739353101; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=7c3hH/C0ty80foBKuB31iqczubI+r+OraZ1ZxIaqE7Y=; b=UMu2+53W5YS5he10J9WX8xogNKA7IbYwggywLY3bf8Z8mlHB/pC2owUMjm/Qf6ycZi ilPgrffdFtgegFfB0mBw4u4XIMbEyP9sm6cO7c+p9i+1KBJeCtSIp6LmFrjQYz9VMIxr XGmPnWs6Bs2tR8Q9sVabTBOkGf0jG27QEw7pgtR1dQZ2ylSZZWHB6NnlBmjFZAzuRYA5 /UKq2tREKoRTdgPoU80+2eMKzRU6EY7e4lBnVpQf4LZfqgjdx84v6uwA12Bm1IP1f5o4 awdHbrERGpCKXWNA6AXFEReAntgWCxYt0u/HCnM04PjqOiTIuZNBNainuUm7F+nTvl3X 2/pQ== X-Forwarded-Encrypted: i=1; AJvYcCWN/FplUA7ZNLzi5PXGS21wg3fSqBIvLA+nqEKWBwQsWpQJfLMHVORe8FXsWcFh86wb2u+YBjW3YQc=@lists.xenproject.org X-Gm-Message-State: AOJu0Yw15Yiti5lXSlHMbASew0cue6HzCPhOXOlmj5MPCWQpVNJpUQvr LaTGQT1yoz/ROJX9SRHmHoeoTiiloIVDDx9vxtsPAIevjYnT1LQ3X4Tq+kCW1hE= X-Gm-Gg: ASbGnctp99upaz7NyTTMrd5+e/dn2EWkmHbug+2R9o6q+l/SLVWbVwlSJ0Qml/CxlDP yzymLwb1b0AytyYA/+qdMbTk8aFPmy+eOhZ2Taj3nxHfkwYzN8sUiorR8MBokhFD7zJY0WrrzPL W7LfYb/uOwjNJLOoO7uahDsuCpkS0OZZ4DV8xpwJlOByGpARG0GPU06R1zxOcOyYGT+AC6yv2T+ WXly7zg2xGe9VZ6OY9XtMyAtDsjunDAC+a5hQUtIlsi6GCTwRh3iHXeFq3cvMcj1UfipL5EykCG cDZRH4RZALYAxEmrUsooa6TMAT9dC0Q4LB5Hn56mLp6A0NeESwC6L4c= X-Google-Smtp-Source: AGHT+IGKiCTY7NdXJy7RVGHpio2VSFkQcy1N+pRmbgyKzcOOLI6LKDmi0Hp5/VBrGDDXcgZfdTMBvQ== X-Received: by 2002:a5d:47cc:0:b0:38b:ece5:5fe3 with SMTP id ffacd0b85a97d-38db48a3fbdmr1234354f8f.1.1738748301323; Wed, 05 Feb 2025 01:38:21 -0800 (PST) Message-ID: Date: Wed, 5 Feb 2025 09:38:19 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/xen: fix xen_hypercall_hvm() to not clobber %rbx To: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= , linux-kernel@vger.kernel.org, x86@kernel.org Cc: Boris Ostrovsky , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , xen-devel@lists.xenproject.org References: <20250205091056.17796-1-jgross@suse.com> <121c5edb-9268-4258-9735-38e4e0f226ad@citrix.com> <3bb7aa63-9acd-4142-b7d6-bde3e92325ef@suse.com> Content-Language: en-GB From: Andrew Cooper Autocrypt: addr=andrew.cooper3@citrix.com; keydata= xsFNBFLhNn8BEADVhE+Hb8i0GV6mihnnr/uiQQdPF8kUoFzCOPXkf7jQ5sLYeJa0cQi6Penp VtiFYznTairnVsN5J+ujSTIb+OlMSJUWV4opS7WVNnxHbFTPYZVQ3erv7NKc2iVizCRZ2Kxn srM1oPXWRic8BIAdYOKOloF2300SL/bIpeD+x7h3w9B/qez7nOin5NzkxgFoaUeIal12pXSR Q354FKFoy6Vh96gc4VRqte3jw8mPuJQpfws+Pb+swvSf/i1q1+1I4jsRQQh2m6OTADHIqg2E ofTYAEh7R5HfPx0EXoEDMdRjOeKn8+vvkAwhviWXTHlG3R1QkbE5M/oywnZ83udJmi+lxjJ5 YhQ5IzomvJ16H0Bq+TLyVLO/VRksp1VR9HxCzItLNCS8PdpYYz5TC204ViycobYU65WMpzWe LFAGn8jSS25XIpqv0Y9k87dLbctKKA14Ifw2kq5OIVu2FuX+3i446JOa2vpCI9GcjCzi3oHV e00bzYiHMIl0FICrNJU0Kjho8pdo0m2uxkn6SYEpogAy9pnatUlO+erL4LqFUO7GXSdBRbw5 gNt25XTLdSFuZtMxkY3tq8MFss5QnjhehCVPEpE6y9ZjI4XB8ad1G4oBHVGK5LMsvg22PfMJ ISWFSHoF/B5+lHkCKWkFxZ0gZn33ju5n6/FOdEx4B8cMJt+cWwARAQABzSlBbmRyZXcgQ29v cGVyIDxhbmRyZXcuY29vcGVyM0BjaXRyaXguY29tPsLBegQTAQgAJAIbAwULCQgHAwUVCgkI CwUWAgMBAAIeAQIXgAUCWKD95wIZAQAKCRBlw/kGpdefoHbdD/9AIoR3k6fKl+RFiFpyAhvO 59ttDFI7nIAnlYngev2XUR3acFElJATHSDO0ju+hqWqAb8kVijXLops0gOfqt3VPZq9cuHlh IMDquatGLzAadfFx2eQYIYT+FYuMoPZy/aTUazmJIDVxP7L383grjIkn+7tAv+qeDfE+txL4 SAm1UHNvmdfgL2/lcmL3xRh7sub3nJilM93RWX1Pe5LBSDXO45uzCGEdst6uSlzYR/MEr+5Z JQQ32JV64zwvf/aKaagSQSQMYNX9JFgfZ3TKWC1KJQbX5ssoX/5hNLqxMcZV3TN7kU8I3kjK mPec9+1nECOjjJSO/h4P0sBZyIUGfguwzhEeGf4sMCuSEM4xjCnwiBwftR17sr0spYcOpqET ZGcAmyYcNjy6CYadNCnfR40vhhWuCfNCBzWnUW0lFoo12wb0YnzoOLjvfD6OL3JjIUJNOmJy RCsJ5IA/Iz33RhSVRmROu+TztwuThClw63g7+hoyewv7BemKyuU6FTVhjjW+XUWmS/FzknSi dAG+insr0746cTPpSkGl3KAXeWDGJzve7/SBBfyznWCMGaf8E2P1oOdIZRxHgWj0zNr1+ooF /PzgLPiCI4OMUttTlEKChgbUTQ+5o0P080JojqfXwbPAyumbaYcQNiH1/xYbJdOFSiBv9rpt TQTBLzDKXok86M7BTQRS4TZ/ARAAkgqudHsp+hd82UVkvgnlqZjzz2vyrYfz7bkPtXaGb9H4 Rfo7mQsEQavEBdWWjbga6eMnDqtu+FC+qeTGYebToxEyp2lKDSoAsvt8w82tIlP/EbmRbDVn 7bhjBlfRcFjVYw8uVDPptT0TV47vpoCVkTwcyb6OltJrvg/QzV9f07DJswuda1JH3/qvYu0p vjPnYvCq4NsqY2XSdAJ02HrdYPFtNyPEntu1n1KK+gJrstjtw7KsZ4ygXYrsm/oCBiVW/OgU g/XIlGErkrxe4vQvJyVwg6YH653YTX5hLLUEL1NS4TCo47RP+wi6y+TnuAL36UtK/uFyEuPy wwrDVcC4cIFhYSfsO0BumEI65yu7a8aHbGfq2lW251UcoU48Z27ZUUZd2Dr6O/n8poQHbaTd 6bJJSjzGGHZVbRP9UQ3lkmkmc0+XCHmj5WhwNNYjgbbmML7y0fsJT5RgvefAIFfHBg7fTY/i kBEimoUsTEQz+N4hbKwo1hULfVxDJStE4sbPhjbsPCrlXf6W9CxSyQ0qmZ2bXsLQYRj2xqd1 bpA+1o1j2N4/au1R/uSiUFjewJdT/LX1EklKDcQwpk06Af/N7VZtSfEJeRV04unbsKVXWZAk uAJyDDKN99ziC0Wz5kcPyVD1HNf8bgaqGDzrv3TfYjwqayRFcMf7xJaL9xXedMcAEQEAAcLB XwQYAQgACQUCUuE2fwIbDAAKCRBlw/kGpdefoG4XEACD1Qf/er8EA7g23HMxYWd3FXHThrVQ HgiGdk5Yh632vjOm9L4sd/GCEACVQKjsu98e8o3ysitFlznEns5EAAXEbITrgKWXDDUWGYxd pnjj2u+GkVdsOAGk0kxczX6s+VRBhpbBI2PWnOsRJgU2n10PZ3mZD4Xu9kU2IXYmuW+e5KCA vTArRUdCrAtIa1k01sPipPPw6dfxx2e5asy21YOytzxuWFfJTGnVxZZSCyLUO83sh6OZhJkk b9rxL9wPmpN/t2IPaEKoAc0FTQZS36wAMOXkBh24PQ9gaLJvfPKpNzGD8XWR5HHF0NLIJhgg 4ZlEXQ2fVp3XrtocHqhu4UZR4koCijgB8sB7Tb0GCpwK+C4UePdFLfhKyRdSXuvY3AHJd4CP 4JzW0Bzq/WXY3XMOzUTYApGQpnUpdOmuQSfpV9MQO+/jo7r6yPbxT7CwRS5dcQPzUiuHLK9i nvjREdh84qycnx0/6dDroYhp0DFv4udxuAvt1h4wGwTPRQZerSm4xaYegEFusyhbZrI0U9tJ B8WrhBLXDiYlyJT6zOV2yZFuW47VrLsjYnHwn27hmxTC/7tvG3euCklmkn9Sl9IAKFu29RSo d5bD8kMSCYsTqtTfT6W4A3qHGvIDta3ptLYpIAOD2sY3GYq2nf3Bbzx81wZK14JdDDHUX2Rs 6+ahAA== In-Reply-To: <3bb7aa63-9acd-4142-b7d6-bde3e92325ef@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 05/02/2025 9:17 am, Jürgen Groß wrote: > On 05.02.25 10:16, Andrew Cooper wrote: >> On 05/02/2025 9:10 am, Juergen Gross wrote: >>> xen_hypercall_hvm(), which is used when running as a Xen PVH guest at >>> most only once during early boot, is clobbering %rbx. Depending on >>> whether the caller relies on %rbx to be preserved across the call or >>> not, this clobbering might result in an early crash of the system. >>> >>> This can be avoided by not modifying %rbx in xen_hypercall_hvm(). >>> >>> Fixes: b4845bb63838 ("x86/xen: add central hypercall functions") >>> Signed-off-by: Juergen Gross >>> --- >>>   arch/x86/xen/xen-head.S | 3 +-- >>>   1 file changed, 1 insertion(+), 2 deletions(-) >>> >>> diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S >>> index 9252652afe59..4378b817ed32 100644 >>> --- a/arch/x86/xen/xen-head.S >>> +++ b/arch/x86/xen/xen-head.S >>> @@ -117,8 +117,7 @@ SYM_FUNC_START(xen_hypercall_hvm) >> >> The 32bit case, out of context up here, also clobbers %ebx. >> >> ~Andrew >> >>>       pop %ebx > > It does not, as this part of the context is showing. Hmm, so it is, and worse, it can't be changed to match the 64bit side.  That's nasty. But while I'm here looking at the code, what's up with #ifdef CONFIG_FRAME_POINTER         pushq $0        /* Dummy push for stack alignment. */ #endif ? That's covered by FRAME_{START,END} normally, and Linux's preferred stack alignment is 8 not 16. ~Andrew