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X-IronPort-AV: E=McAfee;i="6600,9927,10746"; a="359733060" X-IronPort-AV: E=Sophos;i="6.00,255,1681196400"; d="scan'208";a="359733060" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jun 2023 16:41:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10746"; a="838010303" X-IronPort-AV: E=Sophos;i="6.00,255,1681196400"; d="scan'208";a="838010303" Received: from alaird-mobl2.amr.corp.intel.com (HELO [10.212.177.39]) ([10.212.177.39]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jun 2023 16:41:13 -0700 Message-ID: <63477d22-26ef-dd08-a3b0-93931b7d1d16@intel.com> Date: Mon, 19 Jun 2023 16:41:13 -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: "kirill.shutemov@linux.intel.com" Cc: "Huang, Kai" , "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> <20230619144651.kvmscndienyfr3my@box.shutemov.name> From: Dave Hansen In-Reply-To: <20230619144651.kvmscndienyfr3my@box.shutemov.name> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: E33B214000C X-Stat-Signature: atz43kbr7hcenzzqy47p7dit8xgt61b5 X-Rspam-User: X-HE-Tag: 1687218085-209220 X-HE-Meta: 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 hmxvv++z RKM27X6U5lzZesZYl9sZOzIrprgwV77XSRTPNZKhYYUDuqfuN84CR5Glk4Tz5X+SbBv2VlODt4WmbdEaaLEY7o+TWJkmjVE8k3s6/itWWdNhPDpO8CWYsaqbaNG6ZwWEEUhoMaEu9C9H5OxX5eRqtWeX4hGhSUxuP8FDuSf5nzABWQFY8wvGyt24H1a8OL4r/VzEeuzi+5dFMzqdDZttEUmJvYQ== 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 07:46, kirill.shutemov@linux.intel.com wrote: >>> >>> 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? > What's wrong with simple global spinlock that protects all tdmr->pamt_*? > It is much easier to follow than a custom serialization scheme. Quick, what prevents a: spin_lock() => #MC => spin_lock() deadlock? Plain old test/sets don't deadlock ever.