From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (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 D6FFC28B3F3 for ; Wed, 13 Aug 2025 18:44:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755110654; cv=none; b=Mqg1aK35ALjuKhVbJxRCpxAhhWuDyBQtBia1DCUHBkncd5nAF7EYQLWfAbp8dk8TRjIOo5k/uzlqqYy29WSI+LqP7OsibWT0aFXbx0FS8WpPTp0DTNLrjxORCFu0H6L0j/Y5aLOCJjT5+fGLR1VCwJ3y/e0oqAhfYhPaiojmKRU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755110654; c=relaxed/simple; bh=mJD2BkbvjxgDrwFljlBtr6w24VM0830IIP3Zd1UGqAk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QoyAwtwCh8+DSgB9Enm0gQEewvVMCLeYB9KzuSylA2FMFmassJ+zqGfmH2aJ0V+TuLUlGmQj26pKy+MMiztDSGPzF9hafm1fsdKAckNDm/jqWxVvqmoZP1YrHxkFPM2nwIqnKSw6lR3AzNZFTjm/+YujLOQ9AYMf/CRpE8lFZKk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=m7ElGGFV; arc=none smtp.client-ip=198.175.65.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="m7ElGGFV" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1755110653; x=1786646653; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=mJD2BkbvjxgDrwFljlBtr6w24VM0830IIP3Zd1UGqAk=; b=m7ElGGFV6EMoQib6fix1cxVySMlPl+icIa8OdG8TbxYBMUGCb32uYWC9 BpXagqyrB0iabEPxjsPLaEbMgGHnfEbhrEI0H+SIe0pr3WF+EWVhQhI/o b5uAs7tCiY9wAeMsiD7HzMUSYlbDjK2JuS6zipXUfJxTYZwJUSmbo2KEw xrrR6IqWiItVZr/x3lsSFSOh41Sd+V9hTXLU17d5VqROxUyrY73XMWhIb us4kSwiqaG+VqzBEQ5x86PZX87CXZZdrOPEXVPaEozj3D11x0uT062AgT LkMDmCieEtK7z6ndy7sc6ZyDV9msiPkVI+IhfnWyrK7IeK6tUnhXBlYqq g==; X-CSE-ConnectionGUID: FiwJMMAwTcSBub73OET8rA== X-CSE-MsgGUID: grKCm1HbRcmlbdXLIxLXiA== X-IronPort-AV: E=McAfee;i="6800,10657,11520"; a="61036321" X-IronPort-AV: E=Sophos;i="6.17,287,1747724400"; d="scan'208";a="61036321" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2025 11:44:12 -0700 X-CSE-ConnectionGUID: nPlv+xR0QyeNLDSIv7VDtA== X-CSE-MsgGUID: pwdLbm0tR/uzvY8p6z/jIw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,287,1747724400"; d="scan'208";a="171880376" Received: from cmdeoliv-mobl4.amr.corp.intel.com (HELO [10.125.111.131]) ([10.125.111.131]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2025 11:44:12 -0700 Message-ID: <002f259d-2f20-4428-add3-a02650bc728b@intel.com> Date: Wed, 13 Aug 2025 11:44:11 -0700 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 v4 4/6] x86/microcode/intel: Implement staging handler To: "Chang S. Bae" , x86@kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, colinmitchell@google.com, chao.gao@intel.com, abusse@amazon.de, linux-kernel@vger.kernel.org References: <20250409232713.4536-1-chang.seok.bae@intel.com> <20250813172649.15474-1-chang.seok.bae@intel.com> <20250813172649.15474-5-chang.seok.bae@intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <20250813172649.15474-5-chang.seok.bae@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit > +/* > + * Determine if the next data chunk can be sent. Each chunk is typically > + * one page unless the remaining data is smaller. If the total > + * transmitted data exceeds the defined limit, a timeout occurs. > + */ This comment isn't really telling the whole story. It's not just determining if the chunk can be sent, it's calculating it and filling it in. > +static bool can_send_next_chunk(struct staging_state *ss) > +{ > + WARN_ON_ONCE(ss->ucode_len < ss->offset); Please don't WARN_ON() they can be fatal because of panic_on_warn. Also I think this is the wrong spot for this. We should enforce this at the time ss->offset is _established_ which is oddly enough in the next patch. ss->offset = read_mbox_dword(ss->mmio_base); if (ss->offset > ss->ucode_len) // error out > + ss->chunk_size = min(MBOX_XACTION_SIZE, ss->ucode_len - ss->offset); It's a _little_ non-obvious that "can_send_next_chunk()" is also setting ->chunk_size. It would be easier to grok if it was something like: ok = calc_next_chunk_size(&ss); if (!ok) // error out > + if (ss->bytes_sent + ss->chunk_size > MBOX_XACTION_MAX(ss->ucode_len)) { > + ss->state = UCODE_TIMEOUT; > + return false; > + } "TIMEOUT" seems like an odd thing to call this failure. Can you explain the choice of this error code a bit, please? > +/* > + * Handle the staging process using the mailbox MMIO interface. The > + * microcode image is transferred in chunks until completion. Return the > + * result state. > */ > static enum ucode_state do_stage(u64 mmio_pa) > { > - pr_debug_once("Staging implementation is pending.\n"); > - return UCODE_ERROR; > + struct staging_state ss = {}; > + > + ss.mmio_base = ioremap(mmio_pa, MBOX_REG_NUM * MBOX_REG_SIZE); > + if (WARN_ON_ONCE(!ss.mmio_base)) > + return UCODE_ERROR; > + > + init_stage(&ss); > + > + /* Perform the staging process while within the retry limit */ > + while (!is_stage_complete(ss.offset) && can_send_next_chunk(&ss)) { > + /* Send a chunk of microcode each time: */ > + if (!send_data_chunk(&ss)) > + break; > + /* > + * Then, ask the hardware which piece of the image it > + * needs next. The same piece may be sent more than once. > + */ > + if (!fetch_next_offset(&ss)) > + break; > + } The return types here are a _bit_ wonky. The 'bool' returns make sense for things like is_stage_complete(). But they don't look right for: if (!send_data_chunk(&ss)) break; where we'd typically use an -ERRNO and where 0 mean success. It would look something like this: while (!staging_is_complete(&ss)) { err = send_data_chunk(&ss); if (err) break; err = fetch_next_offset(&ss); if (err) break; } That's utterly unambiguous about the intent and what types the send and fetch function _must_ have. Note I also moved the can_send_next_chunk() call into staging_is_complete(). I think that makes sense as well for the top-level loop.