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 596A8C02194 for ; Wed, 5 Feb 2025 09:54:54 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.882045.1292214 (Exim 4.92) (envelope-from ) id 1tfc7F-0008Pm-SR; Wed, 05 Feb 2025 09:54:41 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 882045.1292214; Wed, 05 Feb 2025 09:54:41 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1tfc7F-0008Pf-PO; Wed, 05 Feb 2025 09:54:41 +0000 Received: by outflank-mailman (input) for mailman id 882045; Wed, 05 Feb 2025 09:54:40 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1tfc7E-0008PZ-JZ for xen-devel@lists.xenproject.org; Wed, 05 Feb 2025 09:54:40 +0000 Received: from mail-ej1-x630.google.com (mail-ej1-x630.google.com [2a00:1450:4864:20::630]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 3703adfd-e3a7-11ef-a0e7-8be0dac302b0; Wed, 05 Feb 2025 10:54:39 +0100 (CET) Received: by mail-ej1-x630.google.com with SMTP id a640c23a62f3a-ab74ecfdae4so221732366b.2 for ; Wed, 05 Feb 2025 01:54:39 -0800 (PST) Received: from [10.156.60.236] (ip-037-024-206-209.um08.pools.vodafone-ip.de. [37.24.206.209]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab6e47f1dcasm1073058966b.79.2025.02.05.01.54.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 Feb 2025 01:54:38 -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: 3703adfd-e3a7-11ef-a0e7-8be0dac302b0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1738749279; x=1739354079; 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=26+FUsbPIooMUfvZN5cQVmkmpv5qmC1JGNlRzoWOE7s=; b=Ss32KfA3xzKlaKYtAvyUofcKIrULR74sCiuclNK/DFrPB1dQyL8vLBUz/HJ6aIDxqd jUZ/g8HCzuld91kQ+p9sJKSfTkya90Djvk0/tDemYGscKMnUAJxnqTCVy8RrZl2xieWT bzABh2C/038QGj6G8OTqHR/UafObJpxSDMt/XDG2DdzdOgv3F0ymDjQhJWF5v2xyotjG pAiQLsbR97G1PjxvOQw9+j8bTPeIeRkdkWZgmeeqjqQxluJt6RTu2jMtCsvDpOb2CiQo 9E6dudp/w4xoiFNkzboiyXQUCAFJAWZZ0ny6UTgNlY3/Zefxcw0BRUKQFBTdZ9sEPPlq 9otg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738749279; x=1739354079; 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=26+FUsbPIooMUfvZN5cQVmkmpv5qmC1JGNlRzoWOE7s=; b=RimFYhcFpvvhcyEzE4C5nzPlCS2t0G78Fo/BlwE9yXN4mp8Y0J8sU5YvRj5bjq5fp1 fIMut2h46CdgtCmWmJtAsJQOgKKQpwNU6g1/Y8zZIfVdvrsTMrY9KC5z7nVGcszPT9G5 6p9Cs3/QsqRoU1SNTo/XwPTKGnNtYtl7M8cmVL7W4YgsWj6pbPhwwCYfY2ipiIWdbRF7 KeEI7mpf+DyMyvoCfJ1pYvU0eyhgoumJF5yaIqYVdY92xpIFmN0aIzreBbbOYcTFOULM jjr/vjTQWEoJpDPy+FkInAg2E5SFu2XTfXx6L1VkmQJQSxBrjeL5IHkcgYKe2rvkQt6Z Lkeg== X-Forwarded-Encrypted: i=1; AJvYcCUYDnJJevrwpLfKla1mg4i4on1G0nX0zEx4U9idRkNGQaTwGxCp12SN0A3Joyg7Qd6Ial3MFO2NB0M=@lists.xenproject.org X-Gm-Message-State: AOJu0Yyj+e7qDmONgz2JBKmHUMVy5aZ5g9qKbCe+aZpxCGXXeozI9Fdc PNc3nAqj7kuDoM4ty1SEc3dD+jIRsv+i0ZdSvrC0puUAans/9ypR68SqyjfXUQ== X-Gm-Gg: ASbGncsrMbq+one+ek4EKP3UuAdsbPjnEsjvzzdw2doD4n4JwG4RzDAc8Z08gboanSc QweMgwB78jhO7RrDU0wxeAqiAYlqEa9OS5/cfVZsBRvHEgKUm+tcAd8gJGBC3DPb7skXp01TqmF yPrvVyON6L0c63wBMW/+ebaS3vomQXwSPcid2wJT2apP9ebUmFiRC5KtseQAKip043Kj0vDUMfW 2Qe1f/68bLwrebMr+cH1LYhsKRSpolLSQMLQ3z+Gz9JbhJ6zo/nqNHNFa4ouArmusrUyw8/4+zz d5ANQ4TXVAzu2uDngB6ivyf3QeA2rHu4LpQELbJW4BD6K/JLcS3gzmQlD/sTPe+9FOk5vUKaR2o O X-Google-Smtp-Source: AGHT+IELVJBoh9ZdPEyiDWkaN+/h9BP6aE6Q9sAb3i9RWqC0vw+yNq5Yo+nUVwPqE+xIoZ2Gj1yDIA== X-Received: by 2002:a17:906:f59c:b0:ab6:fee1:60e0 with SMTP id a640c23a62f3a-ab75e0cde78mr234595366b.0.1738749278760; Wed, 05 Feb 2025 01:54:38 -0800 (PST) Message-ID: <0b094f98-401b-4af6-be41-6cfe1bd91560@suse.com> Date: Wed, 5 Feb 2025 10:54:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/xen: fix xen_hypercall_hvm() to not clobber %rbx To: Juergen Gross Cc: Boris Ostrovsky , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, x86@kernel.org References: <20250205091056.17796-1-jgross@suse.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <20250205091056.17796-1-jgross@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 05.02.2025 10:10, 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) > pop %ebx > pop %eax > #else > - lea xen_hypercall_amd(%rip), %rbx > - cmp %rax, %rbx There's no memory access here, but ... > + cmp xen_hypercall_amd(%rip), %rax ... you now read from memory here. That can't be right. Afaict the original use of LEA needs to stay, just with a different scratch register. Jan