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X-CSE-ConnectionGUID: kIH8CuB1Rl2aNfEDpg8ecA== X-CSE-MsgGUID: 2gfO/CVURheqDuae6Zpevw== X-IronPort-AV: E=McAfee;i="6800,10657,11522"; a="75084332" X-IronPort-AV: E=Sophos;i="6.17,290,1747724400"; d="scan'208";a="75084332" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Aug 2025 09:51:00 -0700 X-CSE-ConnectionGUID: kaWlNiynQxCcexXB6m0b8Q== X-CSE-MsgGUID: +eda7AMZQVaytc07TtrRKA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,290,1747724400"; d="scan'208";a="171043051" Received: from iherna2-mobl4.amr.corp.intel.com (HELO [10.125.111.169]) ([10.125.111.169]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Aug 2025 09:51:00 -0700 Message-ID: <4baa3bd4-cbc3-49b3-b8e6-09a2079c8363@intel.com> Date: Thu, 14 Aug 2025 09:50:58 -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 v14 5/5] x86/sgx: Enable automatic SVN updates for SGX enclaves To: Elena Reshetova Cc: jarkko@kernel.org, seanjc@google.com, kai.huang@intel.com, mingo@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, asit.k.mallick@intel.com, vincent.r.scarlata@intel.com, chongc@google.com, erdemaktas@google.com, vannapurve@google.com, bondarn@google.com, scott.raynor@intel.com References: <20250814073640.1507050-1-elena.reshetova@intel.com> <20250814073640.1507050-6-elena.reshetova@intel.com> 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 8/14/25 00:34, Elena Reshetova wrote: > +/* Mutex to ensure no concurrent EPC accesses during EUPDATESVN */ > +static DEFINE_MUTEX(sgx_svn_lock); > + > int sgx_inc_usage_count(void) > { > + int ret; > + > + guard(mutex)(&sgx_svn_lock); > + > + if (!sgx_usage_count) { > + ret = sgx_update_svn(); > + if (ret) > + return ret; > + } > + > + sgx_usage_count++; > + > return 0; > } > > void sgx_dec_usage_count(void) > { > - return; > + sgx_usage_count--; > } How is a plain int-- safe? Where's the locking?