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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E98DEB64DC for ; Mon, 19 Jun 2023 14:31:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 863848D0002; Mon, 19 Jun 2023 10:31:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 813758D0001; Mon, 19 Jun 2023 10:31:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6DCA48D0002; Mon, 19 Jun 2023 10:31:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 5D24A8D0001 for ; Mon, 19 Jun 2023 10:31:31 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id F3D5140D4B for ; Mon, 19 Jun 2023 14:31:30 +0000 (UTC) X-FDA: 80919735540.07.76ABAB7 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf09.hostedemail.com (Postfix) with ESMTP id D406414002F for ; Mon, 19 Jun 2023 14:31:25 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=JTd6tARq; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf09.hostedemail.com: domain of dave.hansen@intel.com designates 192.55.52.88 as permitted sender) smtp.mailfrom=dave.hansen@intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1687185086; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=5ITKgYtGrO55ABk0qQJ9+6oRwecJvx9b6EDmGSaWKhQ=; b=f7Hkzf/TDksk+lNpKTXdcXNXu1NC7DRILaj5sWppOp/fx3cY997F5asq83Ex7tNr5g2QXN 75zuY7FXVLLlewA2LmQ6Xu5QieC3zv3YYK9i4/Vnnw5HKTg/ONtk6f2iOFRgBL9/cZMa/J /5PLL36DcccZX2ZVk13ZycOlAiI+ITw= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=JTd6tARq; dmarc=pass (policy=none) header.from=intel.com; spf=pass (imf09.hostedemail.com: domain of dave.hansen@intel.com designates 192.55.52.88 as permitted sender) smtp.mailfrom=dave.hansen@intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1687185086; a=rsa-sha256; cv=none; b=gKa9RZ0JtGDwe8A9TBP551eu+88wVqtm6s2+F6txNkiqlZEqgwrGo+AS1ZDLZN9apgPcS5 G7sDC+s0ZA7m8zk+Bij/Srt6yGnfszkH8JYvtXPAOqSvDNBzEZ2+s26VmGQCXe3VxtgQ+K Z9U/qsFiKxTsTT9hYGz/gYZVFq++r7M= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1687185086; x=1718721086; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=SyHqZgKn1J7+dVTcmF56m4tqTwlz6VxhZtSS7tFcl4Q=; b=JTd6tARqfP2zdzIJdiEoUq2piPI+NhJPqYCj/nItbiBx2IpSYBTEB8vW TPHbBLa5JbXu0xHC0GwDELePOK+D2i+CUVKEZImFNNZLKjnnwvoEahqxo fvbDPKl+WWLrSon7TwDrUw7vjj2Kmgtonc6pHex4XQPrnSoL23NBPRGB/ JKpW0kgjTYwQRIbYbIizjt+sSZLzYu4ZGWgVPT8yG97S3dcEo+mps7g8/ OLujFG8wU6Nufs5io8dqt85caj+9EPzm7PDKN1qUQ3IF0ZYfdP2cyfY2B 1RH9jsahK6z8HYG1ibPRn11nnSSoafcMPy8q8DFNy5tGrtsWfVUdXzgZ5 Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10746"; a="388720364" X-IronPort-AV: E=Sophos;i="6.00,254,1681196400"; d="scan'208";a="388720364" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jun 2023 07:31:23 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10746"; a="803621243" X-IronPort-AV: E=Sophos;i="6.00,254,1681196400"; d="scan'208";a="803621243" Received: from alaird-mobl2.amr.corp.intel.com (HELO [10.212.177.39]) ([10.212.177.39]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jun 2023 07:31:22 -0700 Message-ID: Date: Mon, 19 Jun 2023 07:31:21 -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 18/20] x86: Handle TDX erratum to reset TDX private memory during kexec() and reboot Content-Language: en-US To: "Huang, Kai" , "kirill.shutemov@linux.intel.com" Cc: "kvm@vger.kernel.org" , "Luck, Tony" , "david@redhat.com" , "bagasdotme@gmail.com" , "ak@linux.intel.com" , "Wysocki, Rafael J" , "linux-kernel@vger.kernel.org" , "Chatre, Reinette" , "Christopherson,, Sean" , "pbonzini@redhat.com" , "tglx@linutronix.de" , "linux-mm@kvack.org" , "Yamahata, Isaku" , "peterz@infradead.org" , "Shahar, Sagi" , "imammedo@redhat.com" , "Gao, Chao" , "Brown, Len" , "sathyanarayanan.kuppuswamy@linux.intel.com" , "Huang, Ying" , "Williams, Dan J" References: <5aa7506d4fedbf625e3fe8ceeb88af3be1ce97ea.1685887183.git.kai.huang@intel.com> <20230609132301.uvvp27yr5kpenl6f@box.shutemov.name> <58f34b4b81b6d6b37d3386dec0f073e6eb7a97ff.camel@intel.com> <20230612075830.jbrdd6ysz4qq7wdf@box.shutemov.name> <4c7effc3abe71aa1cbee41f3bd46b97aed40be26.camel@intel.com> <48d5a29a-878c-665d-6ac2-6f0563bf6f3c@intel.com> <5782c8c2bb3e76a802e4a81c553a21edbaee7c47.camel@intel.com> From: Dave Hansen In-Reply-To: <5782c8c2bb3e76a802e4a81c553a21edbaee7c47.camel@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: D406414002F X-Stat-Signature: ikii8sriprsqpqjtqgss69mtftat9o15 X-Rspam-User: X-HE-Tag: 1687185085-187093 X-HE-Meta: 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 EGpzs+bU SS8IURfLiZCEghbBREfNRrn0EGz9Ehb0tTI/ihHHSc0U7DdlIoLZtbbmx0WoSVhy4CBiDQaxsaCg1bys2MT1INfBlA+dkXt6Poi2JcIul5/X0QcC+shpWzpDdwtCh4WQG1skqkIm2lXkxKw42N9weOEvc/DzGmE/rumpimfnKuqy8BRydHOIWG1XRFQ== 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 6/19/23 04:43, Huang, Kai wrote: > On Mon, 2023-06-12 at 06:47 -0700, Dave Hansen wrote: >> On 6/12/23 03:27, Huang, Kai wrote: >>> So I think a __mb() after setting tdmr->pamt_4k_base should be good enough, as >>> it guarantees when setting to any pamt_*_size happens, the valid pamt_4k_base >>> will be seen by other cpus. >>> >>> Does it make sense? >> Just use a normal old atomic_t or set_bit()/test_bit(). They have >> built-in memory barriers are are less likely to get botched. > Hi Dave, > > Using atomic_set() requires changing tdmr->pamt_4k_base to atomic_t, which is a > little bit silly or overkill IMHO. Looking at the code, it seems > arch_atomic_set() simply uses __WRITE_ONCE(): How about _adding_ a variable that protects tdmr->pamt_4k_base? Wouldn't that be more straightforward than mucking around with existing types?