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X-IronPort-AV: E=McAfee;i="6600,9927,10735"; a="347110911" X-IronPort-AV: E=Sophos;i="6.00,227,1681196400"; d="scan'208";a="347110911" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2023 16:43:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10735"; a="704327805" X-IronPort-AV: E=Sophos;i="6.00,227,1681196400"; d="scan'208";a="704327805" Received: from goels-mobl.ger.corp.intel.com (HELO [10.209.86.239]) ([10.209.86.239]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2023 16:43:44 -0700 Message-ID: Date: Thu, 8 Jun 2023 16:43:43 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v11 12/20] x86/virt/tdx: Allocate and set up PAMTs for TDMRs Content-Language: en-US To: kirill.shutemov@linux.intel.com, Kai Huang Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, tony.luck@intel.com, peterz@infradead.org, tglx@linutronix.de, seanjc@google.com, pbonzini@redhat.com, david@redhat.com, dan.j.williams@intel.com, rafael.j.wysocki@intel.com, ying.huang@intel.com, reinette.chatre@intel.com, len.brown@intel.com, ak@linux.intel.com, isaku.yamahata@intel.com, chao.gao@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, bagasdotme@gmail.com, sagis@google.com, imammedo@redhat.com References: <4e108968c3294189ad150f62df1f146168036342.1685887183.git.kai.huang@intel.com> <20230608232452.yrx2tekugkvral4z@box> From: Dave Hansen In-Reply-To: <20230608232452.yrx2tekugkvral4z@box> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 7BC4C40017 X-Rspam-User: X-Stat-Signature: 79jty5a3tyire93ufhotgotejsk9ryzi X-Rspamd-Server: rspam01 X-HE-Tag: 1686267827-726751 X-HE-Meta: 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 TIfQx++J xDmi+RCBM/if9M8OWU8UVD04c+IGvpxTPFo+PbSNZNoGobEE62bpof8CiP25FAcFi3sBes/iY3AFrhlNDWrzBPsO7Sa/LIm6olv2RgA51TMMIT0RWLLg5KrgqEJ2RkOPYd/NSWfVKdbazL/ZLISv07E4vdLBCCWKmkWsXC6vZB1aMLLM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 6/8/23 16:24, kirill.shutemov@linux.intel.com wrote: >> ret = -EINVAL; >> + if (ret) >> + tdmrs_free_pamt_all(&tdx_tdmr_list); >> + else >> + pr_info("%lu KBs allocated for PAMT.\n", >> + tdmrs_count_pamt_pages(&tdx_tdmr_list) * 4); > "* 4"? This is very cryptic. procfs uses "<< (PAGE_SHIFT - 10)" which > slightly less magic to me. And just make the helper that returns kilobytes > to begin with, if it is the only caller. Let's look at where this data comes from: +static unsigned long tdmrs_count_pamt_pages(struct tdmr_info_list *tdmr_list) +{ + unsigned long pamt_npages = 0; + int i; + + for (i = 0; i < tdmr_list->nr_consumed_tdmrs; i++) { + unsigned long pfn, npages; + + tdmr_get_pamt(tdmr_entry(tdmr_list, i), &pfn, &npages); + pamt_npages += npages; + } OK, so tdmr_get_pamt() is getting it in pages. How is it *stored*? +static void tdmr_get_pamt(struct tdmr_info *tdmr, unsigned long *pamt_pfn, + unsigned long *pamt_npages) +{ ... + pamt_sz = tdmr->pamt_4k_size + tdmr->pamt_2m_size + tdmr->pamt_1g_size; ++ *pamt_pfn = PHYS_PFN(pamt_base); + *pamt_npages = pamt_sz >> PAGE_SHIFT; +} Oh, it's actually stored in bytes. So to print it out you actually convert it from bytes->pages->kbytes. Not the best. If tdmr_get_pamt() just returned 'pamt_size_bytes', you could do one conversion at: free_contig_range(pamt_pfn, pamt_size_bytes >> PAGE_SIZE); and since tdmrs_count_pamt_pages() has only one caller you can just make it: tdmrs_count_pamt_kb(). The print becomes: pr_info("%lu KBs allocated for PAMT.\n", tdmrs_count_pamt_kb(&tdx_tdmr_list) * 4); and tdmrs_count_pamt_kb() does something super fancy like: return pamt_size_bytes / 1024; which makes total complete obvious sense and needs zero explanation.