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X-CSE-ConnectionGUID: pjp8c9NRS6mcppWmxLB0vA== X-CSE-MsgGUID: CQo/WM0kRcaaTsXaeWTdpg== X-IronPort-AV: E=McAfee;i="6700,10204,11253"; a="34963072" X-IronPort-AV: E=Sophos;i="6.12,146,1728975600"; d="scan'208";a="34963072" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Nov 2024 11:41:38 -0800 X-CSE-ConnectionGUID: lxuSWyxxSQOrPh6VQfbszA== X-CSE-MsgGUID: Kcn6ta7pTJmzHSdxAWeG7Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,146,1728975600"; d="scan'208";a="91855774" Received: from rfrazer-mobl3.amr.corp.intel.com (HELO [10.124.223.216]) ([10.124.223.216]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Nov 2024 11:41:36 -0800 Message-ID: <4702f25d-0b01-484c-b542-767dcec97256@intel.com> Date: Mon, 11 Nov 2024 11:41:35 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 07/10] x86/virt/tdx: Trim away tail null CMRs To: Kai Huang , kirill.shutemov@linux.intel.com, tglx@linutronix.de, bp@alien8.de, peterz@infradead.org, mingo@redhat.com, hpa@zytor.com, dan.j.williams@intel.com, seanjc@google.com, pbonzini@redhat.com Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rick.p.edgecombe@intel.com, isaku.yamahata@intel.com, adrian.hunter@intel.com, nik.borisov@suse.com References: From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/11/24 02:39, Kai Huang wrote: > TDX architecturally supports up to 32 CMRs. The global metadata field > "NUM_CMRS" reports the number of CMR entries that can be read by the > kernel. However, that field may just report the maximum number of CMRs > albeit the actual number of CMRs is smaller, in which case there are > tail null CMRs (size is 0). > > Trim away those null CMRs, and print valid CMRs since they are useful > at least to developers. > > More information about CMR can be found at "Intel TDX ISA Background: > Convertible Memory Ranges (CMRs)" in TDX 1.5 base spec [1], and > "CMR_INFO" in TDX 1.5 ABI spec [2]. > > Now get_tdx_sys_info() just reads kernel-needed global metadata to > kernel structure, and it is auto-generated. Add a wrapper function > init_tdx_sys_info() to invoke get_tdx_sys_info() and provide room to do > additional things like dealing with CMRs. I'm not sure I understand why this patch is here. What does trimming buy us in the first place?