From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (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 799271A08D1; Tue, 13 Aug 2024 17:28:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723570104; cv=none; b=iCwKrIQYerP5MX2e4U7tYPxJH4g8yhfC/ULALF76vyq+k+vm4pOIF7W25KVPz4Wj9wGYiGxuvTH+a22cTWFZ0dDu01WamMPrl/tTgrtGWmsHoc4nuhimjyYSTi57RaW6qi2rC2z3sSrXJcvzTdZZqArNCTX/pzqMFkc0qdMk/Gw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723570104; c=relaxed/simple; bh=ndNGlNI76XmLb9K3XXhXrivbtO13RGCPS9qc0tSh6x4=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=pUxOqLxnRQ2INSwDS/l5oNhUBS9XpBwdRbhI83zabhinVc7zZV+bl44rVL7QF0opqedZ6zkQ5urMt5RxKxDChBZtXRTIJ4zn/YCvcYaNGmkVY3jCa6Y4UO/vgXmO+23dRzsyvh2LukUx/ejELVbfemRbyGfYUHWajZAIKMUW+0M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Oex9KA0u; arc=none smtp.client-ip=198.175.65.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Oex9KA0u" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1723570103; x=1755106103; h=date:from:to:cc:subject:message-id:mime-version; bh=ndNGlNI76XmLb9K3XXhXrivbtO13RGCPS9qc0tSh6x4=; b=Oex9KA0ugYNaiQobHMwT4zx1aw+KM7vgVeq603uzUH6LOwV2AcRqFAeH fC/DglIii2w1Mm5d3zFYEQbJpkfDGcTtQWTfDAfXpGfnJDGKWMav5pg9E ZgvQ2ZjY82+VSdUJVobK0E553eUrZR4rFtppOGT7gw5ArctEdtCh/Cj0o afoCxp7BcB3icjB3jooU4+LJWDpt5Sa/YnAzqfq8Dk/T3x/ExlWf/z5vS HCHcnK5IAEwG59z6BBj+FykHf1c0YNGIebUSQfK/ATBwScOHtHF4Vbg0b nMTei0q8ipH+U9KvRlZFh3NI+adoSouaM9AeMYkOKuT2oMLjbQThh6KMp A==; X-CSE-ConnectionGUID: GZGBwi97S8Ko+P1KKluRMw== X-CSE-MsgGUID: mmgiJ8KpRkyQqQZxAjLQvw== X-IronPort-AV: E=McAfee;i="6700,10204,11163"; a="25540709" X-IronPort-AV: E=Sophos;i="6.09,286,1716274800"; d="scan'208";a="25540709" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2024 10:28:22 -0700 X-CSE-ConnectionGUID: AoXMvM4RQl2MaarUe1at7Q== X-CSE-MsgGUID: IobEv8uXSsSBvO99duqDOQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,286,1716274800"; d="scan'208";a="63582081" Received: from yjiang5-mobl.amr.corp.intel.com (HELO localhost) ([10.124.83.191]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2024 10:28:21 -0700 Date: Tue, 13 Aug 2024 10:28:19 -0700 From: Yunhong Jiang To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Question to hv_vtl_real_mode_header in hv_vtl.c Message-ID: <20240813172819.GA6572@yjiang5-mobl.amr.corp.intel.com> Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi, Srinivasan and Dexuan, I have a question to the hv_vtl_real_mode_header in arch/x86//hyperv/hv_vtl.c when addressing one patch review comment. In hv_vtl_early_init(), the real_mode_header is set to hv_vtl_real_mode_header, but there is no setup to the real_mode_header, since the realmode_init() is marked x86_init_noop in hv_vtl_init_platform. How is the real_mode_header(in another word, hv_vtl_real_mode_header) used? Is it to meet the access requirement from do_boot_cpu(), so that real_mode_header->trampoline_start64 will work, although the start_ip is not used? If it's really to support the do_boot_cpu() requirement, how does the non-VTL guest meet the access requirement? The hv_vtl_init_platform() is unconditionally called from ms_hyperv_init_platform(), so I assume all hyperv guest will have the realmode_init() set as x86_init_noop. Thank you --jyh